November 15, 2025 • 56 mins
Ant plants, Chameleon plants, and skinny-peel mangoes. Let's dive into your questions and I'll do my best to answer them.
References
The Genome Evolution and Domestication of Tropical Fruit Mango - Wang et al. - Genome Biology, 2020
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
I called on you for your questions about plant science and genetics and you answered the
(00:05):
call with your questions.
So I'm going to answer those questions.
So you basically have a lot of questions and answers in this episode.
How many times can I say the word question in the space of a minute?
Let's find out.
Anyway, from am plants to how tulips cause the first speculative financial bubble, we've
got some good stuff, so let's dive into it.
Welcome to modified.
I'm your host, Dr. Orlando D'Alange, ex-plant scientist and current science teacher.
(00:29):
This podcast is my attempt to guide you through the science of GMOs and hopefully just
enough of the history and the social context to give you a path forward in your own thinking.
And if all else fails, I hope you'll enjoy some of the surprising stories and fascinating
facts in the world of genetically modified plants.
This is episode 5.5, your questions answered.
I had it wanted to do something like 10 questions, but I realized that I'd probably be more
(00:53):
satisfying to be able to do a deep dive answer for each question, and so I picked my three
favorites.
But I am hoping to do more episodes in this style in future if you would like that, so just
let me know.
And just to mentally prepare you, you'll notice I don't sound so fully scripted in this
episode, and that is because I'm not.
I did some research, had some idea of the things to talk about, but I'm speaking more
(01:14):
of the cuff as they go through, so a little bit of a different style, hopefully that doesn't
throw you off.
So question one, what is the weirdest plant defense mechanism scientists have discovered?
I want to thank @LondonMutt on Instagram for this question, because it allows me to just
ramble on about cool plant stuff, which I'm always happy to do.
So I think there are a few mechanisms that are reasonably well known, but that doesn't
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mean they aren't really weird and worth talking about.
So I wanted to pick a couple that I think you probably have heard of, and then one that
you probably haven't.
So the first one that you probably heard of is Mimosa Putica, aka the Shy Plant.
And it has a pretty special defense mechanism, which you might know about, you might not
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know.
It's a plant that grows kind of as a weed, it's quite a scragally little species, and it's
native to Central America, but these days it's found all over in kind of tropical and
subtropical areas.
It's a big genus that Mimosa comes from.
It's part of an even bigger family, aka, which is the legumes, which includes all beans
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and peas.
You may know that the legumes are unique in the plant kingdom, performing a special symbiosis
with bacteria in the rhizovium genus, genus that are able to pull nitrogen from the air.
In its inert form, what we call molecular nitrogen, which is about 80% of the air around
us.
But unfortunately most plants, well, plants can't use nitrogen in that form.
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They need nitrogen in an organic form, something like nitrate or ammonium where it's basically
the chemical bonds have been modified in a way that makes it kind of accessible to normal
biochemical processes.
And nitrogen is often really limiting for plants, so it's incredibly useful for legumes
that they have, these little bacteria, these rhizobia, that have some kind of biochemical
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wizardry where they can actually pull nitrogen from the air and what we call it fixing, which
is like convert it into an organic form that can be used by the plant.
And in return, the plant provides a physical housing within the roots, like you can pull
up the roots of a legume and you'll find these little nodules, these little round balls
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that are a little bit pink in color because of an enzyme in the bacteria.
And that's where they physically house the bacteria, so there's bacteria have like kind
of a good environment to grow in and they get a bunch of sugar from the plant.
And in return, the plant gets this leg up over all the other plants around it in the form
of an easy access to nitrogen.
So that's just another thing about legumes, that's not the specific thing to do for the most
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aputica.
So the most aputica, defense mechanism we're going to talk about is not defending itself from
the rhizobia, but defending itself from herbivores.
And this is a defense mechanism that has been well known for I'm sure thousands of years
since as long as humans and this plant have interacted.
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But actually, despite thousands of years of kind of human knowledge of this kind of
the existence of this mechanism, the details of how it works, the molecular level are really
going to, there's been recent breakthroughs and there's still quite a lot of open questions
about it.
And so if you don't know a lot about plants, you probably do at least know that they are
(04:29):
not renowned for their fast movements.
I actually think it's useful to think about plants as organisms that do move, but they
move via growing by growing in particular directions.
That's how they kind of reach out and access particular maybe nutrient pockets or better
sunlight or water, but it takes time.
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So depending on the plant and the plant organ growth might take place over several hours
in the fastest cases or several decades in the slowest.
Normally it's something more in between over the space of days and weeks of active growth.
You've probably seen this like most of the time plants, they're not really look like
they're doing very much, but when growth is active, you know, particularly notable in temperate
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regions in spring when new leaves are kind of budding and expanding, you can see very dramatic
growth over the space of a few days normally.
Yeah, but so that's in general plant movement pretty slow, but there are a few exceptions
when it comes to this and one of the most famous is the Venus fly trap.
And then another is the one we're talking about, the rapid folding of the leaves of the
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mimosa pudica plant.
This pudica has a pineite leaves like many legumes and so you can go go go that but think
of it like feathers so they're kind of long leaves with lots of little leaflets all along
the side instead of like the individual fibers of the feather.
And all it takes is a single touch so you can go up to one of these plants, touch it and
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one of its leaves and you'll see all the leaflets along that plant along that leaf folding
up and then that same process spreading within a few seconds to all the neighboring leaves
and all the leaves along that branch will fold up meaning instead of kind of being held
out horizontally they will droop vertically down.
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And this is very dramatic, very obvious and visible and happens within the space of a
few seconds and that is pretty rare and unusual in the plant world.
Now this happens has been known for a while in a kind of physiological way, kind of like
in the sense that it's known that there's a little structure at the base of each leaflet
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called a polvinais that looks like a slight bulge at the base of the stalk of each leaflet
and each leaf and you can see this if your eyes if you look at the plant.
And inside that polvinais are hundreds of cells that are very densely packed together
and under normal conditions they are pumped full of water which tells them very rigid and
holds the leaflet horizontal.
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However, with the right signal proteins called aquaporins inside the membranes of those
cells are activated and that allows water to flow out of the cells quite rapidly and as
they lose water they lose rigidity and that polvinais suddenly like loses its tension
and the leaflet drops and then that's is a reversible reaction.
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So you don't need kind of irreversible growth, it's something you can basically pump water
in or out of those polvinais cells and that's what allows the leaflet to droop or kind of
return to its rigid horizontal position.
It's also known or at least it was kind of assumed that it must be that there are some
receptors so specialized cells within the leaflets called mechanoreceptor cells that trigger
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an electric action potential that can rapidly travel to all the polvinais in the vicinity
of the touch telling them to kind of close up shop.
And this is just because that's similar to how a venous fly trap works.
We know that plants have mechanoreceptors that normally they don't respond very quickly
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but they are definitely sensitive to touch and they have these specialized cells to do that
and we know that plants can exhibit action potentials which action potentials are the
same way nerves work in animals.
Essentially there are proteins in the membrane of basically every cell where the animal
plant or other that regulate the flow of electrically charged ions and for any given
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cell there's a resting balance of ions that is constantly actively maintained but under
certain conditions the regulator proteins change their state and allow ions to flow
in the opposite direction either by removing barriers that have held ions back or by using
energy to pump ions in a particular direction and that changes the electric charge of the
cell which itself is a powerful signal that can be detected by proteins in neighboring
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cell regions and that that tells them okay you should open up the membrane channels,
the transporters and kind of perpetuate this signal.
And in plant sorry in animals we have these long specialized cells called nerve cells where
that action potential signal can pass along the whole length of the cell and we have individual
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nerve cells that can go up like a whole leg they can be very very long and they have a
bunch of specializations kind of these around nerve cells that make them they allow the
action potential to propagate very very rapidly.
Plants don't have cells like nerves that are specially adapted to propagate action potentials
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it's more every cell can propagate an action potential to some extent but they move slower
than in our cells so in the space of seconds instead of milliseconds but one of the things
that plant cells do have which facilitates instead of having you know one giant specialized
nerve cell that the action potential can propagate along the length of all the cells in an average
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plant organ are actually interconnected with each other via tiny cell to cell linkages
so there's actual direct connections where the the membranes have fused and there's no
barrier in between the cells in very small little areas dotted around the connection surface
between the cells record those plasma desmitter.
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Anyway these little connections they have a bunch of different functions in plants but one
of the things that they allow is for the fairly rapid exchange of ions between cells and
that exchange that kind of facilitates the movement of the action potential.
So that was this was already known were not sure at some point early 20th century I think
people found out that action potentials existed in plants as well as animals.
(10:55):
Okay so the piece of the puzzle that connects back to the listener question that has been
harder to pin down to now is why does my most apodica fold its leaves and this is something
that there has been some kind of recent research published on but there just was a complete
(11:16):
death of research scientific research published in this area till now and I think there's a
few it's kind of like worth reflecting on why and I think there's a few reasons one is
that plant science research is very expensive really any life science research these days is
very expensive it requires a lot of people require specialist equipment that all costs money
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so research tends to be focused on things with real world applications that a lot of people
care a lot about and for plants that means overwhelmingly agriculture.
No one eats my most apodica to my knowledge so there's just not that much incentive for
anybody to bother investing a bunch of money into research into it and that means for the
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vast vast majority of plants we know very little about them other than maybe the basics
of their morphology you know features like descriptions of their flowers enough information
that you need to kind of classify them and say okay we kind of know what type of plant
this is and how it fits into the plant family tree but there'll be you know the most plants
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no one has ever done a kind of like a detailed biochemical analysis on their different cell
components and looked into their genetics and all sorts of different things that we have
the technology to do but it's like it takes time it takes money the most apodica we actually
you know have some research into I think probably just because it is such a cool fascinating
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plant that has this feature that people are just quite interested in not interested enough
to want to pay a bunch of money for have a to support a bunch of research teams but enough
to maybe pay a couple of research teams around the world so now there's a little bit just
general plant science background but there has been some recent research that I wanted to
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summarize so Takuma Hagarah and his colleagues from several different institutions in Japan
as well as the University of Wisconsin Madison published a data packed and fairly easy to follow
paper just a few years back in 2022 which I will of course link in the show notes and one of
the first thing they did was document a detailed experimental investigation into why the most
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apodica has this rapid leaf drop and they from what I can see were the first folks to do so
in a scientific paper so to really say like why does the plant have this physiological process
you'd need to rewind evolution over millions of years and be able to chart all of the kind
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of conditions in the environment of the plant that it was responding to through natural selection
or the natural selection was responding to we can't rewind evolution so we can do is kind
of make some reasonable guesses by seeing okay well what you know making some assumptions
about why do we think you know what do we think is the advantage for the plant and then test
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those assumptions and so that's what they did they they already assumed that the reason
that the plant has this behavior we could call it is to defend it against herbivores
and so they were but they're still the first people to actually test that experimentally
to my knowledge and so they check this in a couple of different ways and one of the ways
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they did this and I should have some sort of like GMO plaques on is that they made a genetically
modified most apodica plant which is quite exciting and it's also you know not to keep
digressing too much but I think this also is a good chance to check in on the fact that
most of the genetically modified plants that are produced around the world not in terms
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of like total volume of plants but in terms of like all the different species that have
been genetically modified there's very few genetically modified species or varieties
that are for commercial application but there are tons and tons and tons made all the time
for research purposes and I know this because it's you know the sort of thing I used to do
most molecular plant science labs these days you know one of the tools among many they use
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is genetically modifying plants to kind of ask questions about them so in this case they
use genetically modified and they use a thing called CRISPR which will learn about more
at the end of this season but basically allows you to kind of go in and break specific genes
within the plant genome and so what they did was knocked out is I know the technical turn
that you use knocked out the gene broke the gene that is crucial for the function of
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the polviness and what this means in practice is it basically stops the plants from being
able to have this drooping effect and they also did the kind of stimulated the same thing
using a different method which is like a great piece of scientific technique is like make
sure you can ask the same question using two independent experimental methods just in
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case there was something kind of like an unexpected side effect of your first experimental method
where you it kind of gives you a result and you think it's because of X but actually it's
because of some hidden feature of your experimental setup so it's good to like try to ask the
same question multiple different ways so they made this genetically modified version
of the plant they also just use a chemical that stops the polviness working and in both
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cases they looked at how long potential herbivores in this case it was some caterpillars
and some crickets spent feeding on the leaves and they just kind of recorded that and were
able to show fairly clearly the plants that lack the ability to droop were basically had
their leaves eaten more it's pretty much as simple as that and it seems like quite a simple
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experiment but it's like it does you do have to kind of do it carefully and make sure you're
really tracking it and and have these controls in place but for as far as I can see they were
the first to just say like yes okay maybe this isn't exactly why it evolved but we do know
that at least this drooping mechanism at least in a laboratory setting does reduce herbivory
on these plants so anyway that's something that was very cool another kind of cool defense
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mechanism I wanted to mention but I'll just touch on very briefly so I can get to my like
favorite one is ant plants defense by ant so that's right there in fact hundreds of species
of plants mostly in tropical and subtropical parts of the world which have a mutualistic
symbiosis with ants mutualistic symbiosis meaning they living very very closely and intimately
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together and each side benefits just like the rhizobial legumes symbiosis we talked about
that's mutualistic so is the ant and plant symbiosis depending on the species the plant might
provide a special structure that houses the ants so this is not just ants kind of like
happen to be near to the plant they live inside the plant most of the time and then in most
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cases the plant also has a specialized organ that provides food there's this can happen
in various different ways but it's not like nodules little food packets so the plant produces
for the ants and in return the ants fiercely defend the plant against any would be predators
well herbivores they get too close and there's a fun word for this murmurco fights literally
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ant plants but doesn't murmurco fights sound cooler so yeah go google murmurco fights and
look at some of the really cool kind of ant houses of these plants grow but in the interest
of time I will move on to the next one because otherwise this episode might be super long
I wanted to end this long answer to this still is still our first question with my favorite
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weird plant defense mechanism the chameleon vine so you know chameleons these crazy lizards
that can change color to mimic their backgrounds and blend into their surroundings well in
2014 a bombshell hit the botanical community two researchers from Chile a nesto geonoli and
Fernando Carasco-Ura published a report of a tropical vine boughela trifoliata that unique
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among all known plants can do what chameleons can presumably this property has been known
to those living in and around the native forests of this vine for a very long time but the
native rangers not that far like it was not known to that many people before and there
been no scientific reports published on it that can help you know one of the benefits
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of a scientific paper is just a kind of way to easily alert researchers around the world
to something and so in 2014 they published a paper they're not just said okay the vine
exists the vine had already been described briefly before but what they showed was that
this vine has a chameleon kind of property rather than changing color what this plant can
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do is that the leaves of this vine change shape and also their kind of texture and color
depending on the tree that they're growing on and I'm going to link the paper again in
the show notes so you can look it up and it is actually quite astonishing this is not like
a some super subtle thing where you have to kind of squint you're like okay I guess those
leaves are like maybe a little bit more round you know this is quite dramatic it's not a
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perfect camouflage but it is pretty good and like it's so amazing that you can even have
one boughela trifoliata vine that happens over its whole length to be growing on three
different trees at different points along it's kind of main branch and and it will have
different shaped leaves at each of those points based on the tree that it is growing on so they
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able to show this isn't like there's just some kind of variation in the morpho types of this plant
that's a fairly common thing that if you kind of have a field of plants within that field you
might find different versions with different leaf shapes no it's literally one individual can
have different leaf shapes and that if you experimentally grow the vine in a lab give it different
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kind of host trees to grow on you can see that it does indeed adapt its leaf a leaf shape to the
vine that you give it even artificial vines that don't exist in nature sorry artificial host trees
and this kind of blue everyone's mind because there's just no precedent for this in the plant world
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and so that was in 2014
and they did oh yeah a key thing i wanted to point out is that they also in the 2014 paper showed
that this does indeed reduce habivory so the kind of very similar to the previous paper they're
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basically able to show that this property does reduce the amount of time the insects spend basically
it's what it seems like is that the insects notice the leaves less just like with a chameleon it can
kind of like blend into the background more and but they were not able to show how this mechanism
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works and i would say like there's a couple of updates i'll give you but it's still very much an
open question i do not think it's been definitively solved at all and there was a couple of like
main approaches or like theories about this so in 2020 an american amateur researcher which i think
is really cool to shout that out because as these days it's very hard to kind of participate in
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scientific research if unless you work you know unless you have a PhD and you're working within some
kind of a traditional institution but it can be done so there's an american amateur researcher
teamed up with a german researcher at the University of Bond to show that the vine will attempt to
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mimic a plastic vine that it's grown next to and that they propose that this is due to plant vision
which is not as crazy as it sounds no one suggesting that plants can see like animals can
but plants can certainly sense and respond to light and what they're hypothesizing as that these
plants have specialized cells that are particularly sensitive to light and can detect basically roughly
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the shapes of the leaves that they're growing near and then kind of there's a feedback mechanism
to recreate that shape which you know that ability to kind of basically see shapes would be unprecedented
but and they and they did not they did not find these cells they did not show that mechanism
they were more showing like well it seems logical because we can give it some shape it's never
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you know encountered before in in its evolutionary history and it's still able to mimic that shape
so it must be able to somehow get information about the shape in real time and also it was a
plastic leaf it wasn't giving off any natural plant chemicals that might be you know the other main
theory is okay each of the different trees that happens to grow in the native range of this vine
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has a certain kind of chemical signature to it so all the plant needs to do the chameleon vine
is detect that chemical signature and kind of like switch between its different pre-programmed
leaf shapes but that does not seem to be the case um and oh yeah and so another paper came out in
2022 so like this is all very recent stuff still very much ongoing question showing that there
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seems to be some overlaps in the leaf microbiome of burky letrofoliata and its host trees
suggesting that microbes growing on the leaves provide a signal to the vine to start mimicking
and like like as I just pointed out that doesn't seem to stack up with the fact that it can also
mimic some random plastic leaf shape because the plastic leaves will not have microbes growing on them
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or least it shouldn't and so it doesn't seem to make and also this other group with their kind of
hypothesis that something about the microbiome of the leaves they haven't got a mechanism for that
yet like this is still a very open question so if you're like wow chameleon vines that sounds amazing
get involved there's plenty of open questions there like I mentioned you don't expect to get a
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bunch of government funding to study this because there's really you know no one eats this chameleon
vine with that said sorry to get on my soap box but you know this I think you know could end up being
a classic example of where basic research and something that seems very niche and obscure could
pay off because whatever it is there seems to be some totally novel kind of physiological mechanism
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in this plant and if you can work out what that is who knows maybe it will have some really interesting
very practical applications but you don't know until you find out anyway so that
long rambling journey will wrap up question one for now okay questions two and three will not be quite as
long I promise okay the next question are darlie speckles like tulip distortions and caused by a virus
(26:15):
so I love this question from @fckisberglettis on instagram because it gives me a chance to talk about
ornamentals aka flowers which have some really interesting botany and history and if any of this
sounds interesting to you gonna have this stuff that I'm about to talk about you can read a lot more
fun flower stories the intersection of history and botany in flower confidential by Amy Stewart a
(26:38):
really enjoyable read I recommend it so but let's dive into it so the question has two parts it's
the the darlie speckles and are they like tulip distortions which is caused by a virus so I'm gonna
start with talking about the tulips because some of you may know about this but some of you probably
do not there are a lot of things to talk about tulips they have a lot of kind of juicy history to them
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you probably know tulips they have these ball shaped richly colored flowers and their name in fact
comes from or the name in english from the turkish word for turban because the resemblance between
the flowers and they're kind of luxurious turban and that's you know particularly fitting because
they were introduced into europe from central aysia via turkey in the 16th century and by that point in
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the 16th century the wild tulip flowers from central aysia have been selectively bred you know for a
long time in central aysia to produce beautiful ornamental flowers and so you know by the time they
arrived in western europe in the 16th century these were not you know the wild flowers this has
already domesticated ornamental and it really blew people socks off they people fell in love with
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these tulips and in particular the dutch went crazy for tulips reaching a peak known as tulip
mania in the early 1600s so this is about 400 years ago and it was you know within a century of tulips
first arriving in western europe like it was they were a pretty overnight sensation tulip mania
all kind of peaked and already was we'll see collapsed within the space of a century
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i am not sure where the cause and effect lie but ever since tulip mania so around that kind of like
early 1600s the netherlands has been a global center for floriculture meaning the cultivation
and trading of ornamental flowers and they are still the global leader in that industry i don't know
quite what it is whether tulips are really anything to do with it or it's kind of like they're just
(28:35):
another symptom dutch people and floriculture seem to just really go together um so tulip mania
wasn't just a name for a craze but refers is normally used to refer to a speculative bubble that
happened kind of towards the end of this period of intense interest in tulips as people started
to trade tulip bulbs are higher and higher prices and in a way that resembled a stock market
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where they weren't even often literally trading the bulbs but just kind of on paper trading the bulbs
are higher and higher prices until as tend to happen one day that speculative bubble burst
as people realized like okay the values were trading has really like these are just some flowers
and actually one of these values based on and people completely lost confidence overnight
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and people lost their fortunes overnight and it's a very famous event in history of economics
as a really early example of the sort of speculation that you see in stock market bubbles
that then lead to crashes um but i'm not gonna go too much into the economics i just wanted to talk
a little bit about tulips like one of the things within tulip mania um which was
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the most valued tulips were those that had streaks of yellow and white in kind of wild irregular
patterns in the petals which are known as um broken tulips and the way that this works is that these
plants as was unknown at the time this was actually just kind of something that people
(30:04):
researchers realize in the 20th century those plants were infected with a virus
could which you know when it was discovered it was named tulip breaking virus because of this property
and that where the virus kind of as it spreads through the flowers and the different cells of the plant
it removes color from the infected cells and so it creates these wild patterns this kind of
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variegation but it also it doesn't just like oh it makes the flowers look cool it does but it also
does weaken the plant and it you know you probably know that tulips have bulbs where kind of they'll bloom
and then they'll basically kind of look like they shrink back into the bulb for another season
the bulbs weaken over time with the tulip breaking virus so they don't have an indefinite
(30:55):
lifespan anymore they will die after a few generations which is why today there are very few
truly virus broken tulips in cultivation there are i mean if you for example happen to live in the
Seattle area like i do and you know that just north of us in scadget valley there's a famous
(31:17):
tulip festival and you can see all these different kinds of tulips you'll see plenty of examples
of ones that have like streaks of white or yellow in the petals that sounds like this tulip breaking
virus it's not the same thing so those ones that you can get commercially they have in fact been
just bred through traditional plant breeding methods which we'll learn more about in upcoming
(31:38):
methods episodes in order to achieve that stripy pattern i did for a little bit of digging
found out that there does seem to be one truly virus broken tulip variety that is still
commercially available although it's hard to get your hands on it's called tulip absalon that's
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like the name of the variety and i got to say from the pictures it looks really really gorgeous
and i would love to get my hands on one it does i got to say it looks cooler than the the streaky tulips
that are bred with conventional plant breeding methods so in january 2025 research is one
(32:22):
carerro and hillon at the University of Alberta like that sorry stop go back so i'll just end on
or this kind of tulip section by saying that in january 2025 so this year you know this is
uh i can mention tulip breaking for viruses was this thing that was first noticed four centuries
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ago and there's take until this year for someone to even propose a model of what they think
might actually be going on it's like okay we know there's a virus but how does it produce these
particular patterns and they basically it's these researchers one carerro and hillon at the
University of Alberta proposed a mathematical model that could account for the pattern of the
breaking on the petals and why the virus would create that specific infection pattern and so
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like you know i'm not going to go into all the details of that but i'll link the paper in the show
notes to just a show like just because people can see a phenomenon doesn't mean that we know
why it works even something that you know i know maybe not everybody in the world knows about
tulip breaking virus and like the tulip may be it but it's reasonably well known pretty like
famous thing within botany and there's still a ton of open questions okay now dali is
(33:37):
dali is like tulips grow from seeds yes but also from underground structures tulips make bulbs
which are underground storage organs that exist that consists of a shoot apical meristem surrounded
by specialist leaves very much like an onion so onions are bulbs tulip bulbs are bulbs
(33:57):
very like analogous to each other if you slice over an onion or a tulip bulb they all look very
similar um dali is make tubers the same sort of structure as potatoes tubers are flessy pieces of
root or stem they contain a lot of carbohydrates to store energy and have lots of smaller meristem
(34:18):
from which new growth can emerge so the structures are a little bit different but similar and effect
underground storage organ there can be dormant and then new growth will emerge when planted normally
in spring while tulips are native to central Asia dali is our native to mexico and central america
from my understanding dali is have long been cultivated in the region uh mexico central america
(34:43):
as a food crop um yes dali are tubers are edible so are tulip bulbs in fact eating tulip bulbs that
had piled up during the second world war was part of how Dutch people survived a forced starvation
imposed by the Nazis in the winter of 1944 unpleasant episode um but back to the dali is pretty much
as soon as europeans started colonizing the region of mexico and central america they were taken
(35:07):
by the beauty of dali is and built on existing substantial diversity in varieties to create more
and more ornamental varieties of dali which has really just continued ever since um dali is
are maybe not quite in the same league as roses in terms of share of global flower market but they are
definitely you know one of the heavy hitters and they have very passionate fans um probably unsurprisingly
(35:33):
dali is are the national flower of mexico more surprisingly given the total lack of historical
connection they are the city flower of seattle as far as i can tell uh you know i tell me you know
let me know if i'm wrong about this there was a nationwide craze for dali is across the us in the
early 1900s including in seattle but it's not limited to seattle but seattle was hosting a world's fair
(35:56):
in 1906 and didn't have an official city flower not the city's need an official flower but you know
didn't have one yet and some some local dali are lovers for the an official declaration making dali
as the city flower would be a kind of impressive show of seattle's cultural sophistication ahead of the
world's fair um and you know mostly that that has not meant very much for seattle um unlike you know
(36:20):
portland is city of roses there portland origen you'll find tons and tons of roses around the city
kind of rose iconography you don't see a bunch of dali are iconography around seattle um but there is
a dali as show garden in seattle's volunteer park with different dali are varieties the bloom in
august which is the normal time for dali is and it's absolutely gorgeous so if you happen to be in
(36:43):
seattle in august go to volunteer park check out the dali garden it's lovely um something else that
I learned when researching this there is a town in the Netherlands just to go back to much dutch
people love flowers who did not want to miss out on the floral action with dali is and since 1936
has hosted a dali parade and this is not just you know some okay there's some flowers and you
(37:05):
kind of like goes through the streets and people hand out flowers or something no this is a pretty
big deal it's the town of sunda not sure how to pronounce that correctly even though I do have dutch
heritage do you not know how to speak dutch um but so it's the town of sunda but all the local villages
around this town compete by creating massive elaborate floats decorated entirely with dali is and
(37:29):
the dali is they grow themselves and apparently you know according to the internet each year apparently
about six million dali is a grown and used in the parade floats and I really recommend just like
look up some pictures of this online the floats are really cool the parade is called the bloom and
course so it's in it but I think if you just go called dutch dali a parade you'll get it um so I'd
(37:50):
recommend that these days there are probably thousands of distinct varieties of dali is and by
varieties I mean distinct genetic lineages and the aesthetic diversity of dali is is much greater
I would say than for most ornamentals there are different varieties of dali is that just you know
to have first glance don't look like they're from the same species at all um and there's certainly
(38:16):
this diversity a lot of it has come from small time breeders working in the same sort of way as
people have done for centuries so we're learning upcoming episodes about some of the more modern plant
breeding approaches and methods that have been developed in the 20th century and 21st century
you know particularly obviously we'll get to gmo's but we'll learn about some other stuff along the way
(38:39):
um but there's also what people have done for a long time which is plant a bunch of different seeds
make kind of crosses by transferring pollen between plants and kind of just like see what you end up
with and one of the great things about dali is is because they produce these tubers the tubers basically
(38:59):
allow you to they there's no kind of production of seed and transfer of genetic material between
different parents that goes into producing a seed it's just a clone like the tuber like with potatoes
like the tuber is just a piece of the adult plant you can in fact take the tubers break them apart
into smaller pieces and propagate basically clones of that same adult plant so once you get like a nice
(39:23):
dali a variety that has beautiful flowers that you love you don't risk kind of losing it again
as it interbreeds with other individuals you can just propagate that dali are through tubers indefinitely
that also make dali as excellent candidates for mutation breeding which we'll learn about
um the next in two episodes time um but it's basically deliberately exposing plants than
(39:47):
mutagenic radiation or chemicals that are mutagenic which modifies DNA sequences randomly um
and you can do this you're gonna take a dali attuber like break it into hundreds of small pieces
expose it to this mutagenic radiation or chemicals and then and then kind of let those tubers like
plant them see what the flowers look like and there's a good chance you'll get at least one that
(40:09):
has some new interesting flower phenotype and then you can start propagating that in haypressedo
you've got your new dali a variety um and so you know there's that's mutation breeding has been
particularly successful in the dali a breeding industry so let's connect this back to the original
question like tulips that are varieties of dali are with variegation meaning stripes and dots
(40:33):
in the flowers that lack pigment or have a slightly different pigment and unfortunately sort of
short answer to this is it seems as far as I can tell there is no viral infection that causes this
it's just one of the many many different varieties that popped up as people have been breeding daliers
they are just genetic variations so sorry I could have answered this question which is a simple no
(40:55):
but where would be the fun in that and I'll link some of the references that I was drawing from in
the show nights okay let's do a final question can we GM a mango so that it has edible skin like an
apple so I want to thank mechanical bees on reddit for this question can we GM a mango so that
(41:19):
has edible skin like an apple this time I'll start with the short answer probably yes
um so let me share some my thinking about this firstly what is it that makes the mango skin kind
of unpalatable there are a few different pieces this when it's quite thick uh like quite physically
(41:40):
difficult to eat so that would be one issue then it's just quite bitter and then kind of sub sub
bullet point of bitter there's a specific bitter compound in this peel called ursial or
jury ursial um which is particularly problematic it is named for the Japanese name for the lacatry
(42:06):
and lacatries and mango trees are in the same family that the anarchy de ac a most of the plants in
this family produce ursial in some of their organs the family includes cultivated plants like mango
cashew and the lacatry which is used to make true lacca using um Japanese lacquer wear the family
(42:26):
also includes poison ivy poison oak and poison sumac and so that might give you a hint about the
problem here ursial um irritates skin by triggering an inflammatory immune response or what we call
an allergic response in those that have sensitivity this is uh potentially life threatening for most
(42:47):
of us who are not kind of hypersensitive to it it's just annoying and a bit painful um so that
hypersensitivity when we say allergic we actually mean a hypersensitivity but a allergic reaction just
means it triggers an irritation that is based on an immune basically a gentle immune response
that's an allergy is kind of an inappropriate immune inflammation um and um yeah everyone pretty much
(43:18):
everyone gets it to some extent both for poison ivy and for mangoes um and but the mount in mangoes
is kind of less problematic and this specific there are kind of different versions of ursial
um and the one that is in mangoes is one that tends to be less irritating um triggering less
(43:40):
triggering of allergic reactions than the one that is in poison oak um so that's why mangoes tend
to be less problematic for people but the the chemical is particularly concentrated in the peel
so for most people you know the amount that you get exposed to just from eating the fruit of the mango
isn't enough to cause much of a reaction maybe like a slight tingling people who have
(44:02):
uh what we call like in everyday speech and allergy to the mango it can there's a whole range of
how sensitive they are but for most people if you ate a whole mango peel you would not enjoy it
you would have some sort of unpleasant irritating reaction um
(44:23):
so if you were to make a mango with a peel like an apple that you'd want to eat you would need to do
quite a lot you'd want finne a skin that is less bitter but you definitely want
to get rid of the ursial so i found a paper in 2020 that they published the mango genome
it was led by a large research team in hyena and china and as part of the work they looked at
(44:45):
transcription so that's gene expression in different tissues and they pinpointed a set of genes
that are encode enzymes called chalcon synthases um and particularly they found the chalcon
synthases that are expressed more in peels and just based on what we know about the functions of
similar enzymes known from known from other plants they're pretty sure that these are the enzymes
(45:09):
that are responsible for making the ursial and the peel um so if i wanted to make a transgenic mango
that had peeled that was more palatable one less irritating what i'd want to do is knock out or break
those specific chalcon synthase genes in the mango and now that we know what those genes are
it's a lot easier to do because in that we'll we'll dive into all of this when we explore how you make
(45:33):
gmose but obviously you kind of have to know what you want to add if you're trying to add in new genes
or what it is you want to break or modify in the existing genome like if you don't know that you
don't have any way to begin your project so knowing that is not everything you need but it's a very
important first step um bigger problem that i can see is that no one seems to have made a transgenic
(45:59):
mango meaning an adult mango tree that has had its genes modified using laboratory methods um
like many trees uh mango is hard to do breeding with and most mango varieties around the world are
random mutations that appeared and then cuttings from the tree have been cloned over and over kind of
(46:19):
just like you can take um tubers and break them apart and grow new darlias from them with a lot of
fruit trees you can just take various pieces of the tree and with a little bit of gentle coercion
and sometimes a little bit of chemical help you can get those little pieces of tree those cuttings
to grow into full adult trees and that is how most fruit trees are propagated not from seeds but
(46:43):
from cuttings of adult plants um and that's great in some ways but it also means it's hard to do
breeding with those trees that's how to create new varieties um we will see that making a
transgenic plant takes a lot and mostly involves grinding the plant into cells and using one of a few
methods to get DNA into those cells and then getting the cells to turn into adult plants and those
(47:07):
steps can be very easy for some plants and seemingly impossible for others and i suspect for
mangoes it's both difficult but also just not something that anyone is pouring tons of money and
attention into is the bigger problem so like a method of how exactly to do this for mangoes is lacking
mango is a big crop um you know it's not it is pretty commercially successful all around the world
(47:32):
but it doesn't come close to the global market value of staples like rice and potatoes so there's
just not as much economic and sensitive to bother trying to work out how to create transgenic
maven goes so that does not mean that it is impossible um but let's just say maybe it is impossible
and we can't for some reason just the normal methods that have worked for many other plants just
(47:55):
won't work for mangoes we cannot genetically modify them then you'd have to rely on conventional
breeding but mangoes like as i mentioned kind of basically all fruit trees are propagated by cuttings
not seeds um because in you know to dive into this a little bit more the seed will not give you a
tree that looks like the mother tree that produced the fruit it came from the seed has a combination
(48:18):
of maternal and paternal genetic material the fruit around the seed just comes from the mother
and so the you know you may and generally the fruits are what we're interested in but this you know
all the other organs of the tree come are what we call the other mother and then the father tree
just gives its pollen um and just to like i know i'm kind of complicating things in case you're
(48:42):
wondering like there's mother and father trees most trees most plants are um hematoricitic they are
they produce male and female organs some aren't sometimes particularly with fruit trees you do
sometimes get male ones and female ones and you'll see only the female ones produce fruits
the male ones just produce pollen anywhere there's a bit of a but in general you know the seeds
(49:06):
are the end result of that sexually production the seeds will have a combination of genetic variation
from both parents and so will not look like the mother tree um and so that can be you know if you have
a variety of mango that uh is great um and you love the fruits that it produces you want to just
(49:26):
reproduce that plant via cuttings to always make sure you get identical fruits every time
um and we'll we'll learn more about that in the coming episodes if you're like wait that was too much
and i'm confused um and so if you're wondering like is this just an issue for fruit trees no it's an
issue for all plants but in most crops where conventional where breeding based on sexual production is done
(49:51):
um this problem has been evaded by deliberately inbreeding plants for many many generations
so the point where there is no genetic variation or whatever genetic variation is there is the genetic
variation you kind of want and are controlling um but that takes many generations of inbreeding
(50:12):
which is fine if you have like wheat which you can actually get two generations out of it in a
single calendar year with the right coaxing you can breed you know you can inbreed that wheat
ten generations in five years but a mango needs many years to get from seed to sexual maturity um so
(50:34):
it's just like slow and painful to use that kind of method and that's where just in general this is
true for all fruit trees trying to do conventional breeding with them is slow and painful to give an
example there's this new apple variety the cosmic crisp that was released in Washington state in 2022
I think it is more widely available these days I'm a big fan of it um it took a huge team of agricultural
(50:58):
scientists 22 years to make this one apple variety that is essentially just a cross between two
prior apple varieties um so it's it's far harder to breed new tree fruit varieties using conventional
breeding methods uh and the same I'm sure is just as true of mangoes people are breeding mangoes
(51:21):
it is there are teams of people around the world doing this it's just like slow and painful and like
it said there's not as much economic kind of interest around mangoes so there's not as much effort
going into it um and there are you know also to point out that all are already many different
varieties of mangoes that exist it's not a kind of urgent pressing problem um but as we'll see kind
(51:46):
of in the coming episodes there's all sorts of reasons why even when you have like a perfectly
good variety of a plant you always kind of want to create more and have more options on the table
particularly in case there are diseases that come up that threaten the existing varieties
um okay anyway so plant breeding could be an option it's going to be slow and painful but it could
(52:06):
happen if people really would have determined to get a mango without a ratio in its uh peel and there's
a precedent for this that I thought was a fun opportunity to bring it up that was a pretty um actually
there's like quite a lot of interest in breeding out unpleasant chemicals from plants in the 20th
century and one of the most successful examples of this is canola which canola is brusica wrapper
(52:30):
that's from the mustard family um and it is like as long been known for its oil that comes from its
seeds but that oil was more just used in an industrial lubricant or for other kinds of purposes not
for eating because it's very very bitter naturally because of a chemical called a ruchic acid
and some researchers in the mid-century in Canada were like we are not going to settle for that
(52:57):
we think there's a lot of this plant grows really well in our climates and our soils
um and if we can just make this this oil edible it could be an amazing oil plant
for you to make cooking oil or you know eating oil and what they did was use chemical breeding methods
to completely eliminate the ruchic acid or to get it to such low levels that it's not bitter anymore
(53:21):
and it is perfectly edible and pleasant um and the product of that breeding was the kind of plant
and and oil that we now call canola and this is like fun bar trivia fact that canola is a acronym
that stands for Canada Oil Low Acid so the the plant is brassica wrapper but the particular
(53:44):
variety that is that can be used in cooking is called canola uh I think both because um you know
you wanted to have like a nice marketing gimmick like indicator this is a new product this isn't
the same old brassica wrapper that you know but also because the conventional name for brassica
wrapper in English at least as a um as a crop was rapeseed and that is actually still how it's mostly
(54:08):
known in the UK and in some other areas but like rapeseed you can imagine is not as a name that has
unwanted connotations um and so canola just sounds great um and so canola is what's used more in
North America um anyway so that's like there's precedent there for the sort of you know you could
imagine following a similar approach to get rid of the original in the mango peels um but we
(54:34):
that's not been done yet so in the meantime what do you do with all that is guided mango peels
researching this I did find some papers by researchers such as dv's sudakar at indian agricultural
research institute in New Delhi developing methods to take discarded mango peels from mango
processing and extract usable chemicals from them to reduce food waste and just as a reminder
most crops don't make it to the end consumer in an unprocessed form so there's a lot of waste
(54:59):
that builds up in the processing of plant products uh and it can be like um uh great to see like
what can we do with that how can we make sure that that um doesn't just go to waste and pile up
and decompose and release methane gas which is a powerful uh greenhouse gas um so just a shout out
(55:20):
for all of those diligent workers working on these not very glamorous questions like how can we
processing great valuable products out of mango peels um and and yet just to kind of remind you
that the original question was about like could we GM a mango peel a GM mango to have a edible peel
I think yes you'd have to get that genetic modification method to work which would probably just mean
(55:45):
like testing out a bunch of parameters until you get one that works and then we kind of know
which target genes would want to go after I think it would be doable I just doubt that anyone
would be that motivated to do it um but we'll see uh be really be very fun to see that in a few years
edible kind of mangoes you can eat like an apple coming onto the market um okay so I think I'll wrap
(56:07):
up here because I think I've been talking for a pretty long time um if you hated this don't worry
we'll be back to a regular scripted narrative episode after a two week break so I can catch up with
writing and recording if you liked it let me know I could definitely do more Q&A episodes based
on your interest dear listener until let me know by emailing Orlando@modifypod.com or that's Orlando
(56:30):
at modifypod.com or you can find my socials at modifiedpod.com that's the website that's also where
you can find the show notes and just as a reminder I'm Orlando D'Alanj this is modified as always
please do subscribe leave a review and tell a friend if you're enjoying the podcast and I hope you'll
We'll tune in again soon, bye!
[BLANK_AUDIO]
I called on you for your questions about plant science and genetics and you answered the
(00:05):
call with your questions.
So I'm going to answer those questions.
So you basically have a lot of questions and answers in this episode.
How many times can I say the word question in the space of a minute?
Let's find out.
Anyway, from am plants to how tulips cause the first speculative financial bubble, we've
got some good stuff, so let's dive into it.
Welcome to modified.
I'm your host, Dr. Orlando D'Alange, ex-plant scientist and current science teacher.
(00:29):
This podcast is my attempt to guide you through the science of GMOs and hopefully just
enough of the history and the social context to give you a path forward in your own thinking.
And if all else fails, I hope you'll enjoy some of the surprising stories and fascinating
facts in the world of genetically modified plants.
This is episode 5.5, your questions answered.
I had it wanted to do something like 10 questions, but I realized that I'd probably be more
(00:53):
satisfying to be able to do a deep dive answer for each question, and so I picked my three
favorites.
But I am hoping to do more episodes in this style in future if you would like that, so just
let me know.
And just to mentally prepare you, you'll notice I don't sound so fully scripted in this
episode, and that is because I'm not.
I did some research, had some idea of the things to talk about, but I'm speaking more
(01:14):
of the cuff as they go through, so a little bit of a different style, hopefully that doesn't
throw you off.
So question one, what is the weirdest plant defense mechanism scientists have discovered?
I want to thank @LondonMutt on Instagram for this question, because it allows me to just
ramble on about cool plant stuff, which I'm always happy to do.
So I think there are a few mechanisms that are reasonably well known, but that doesn't
(01:37):
mean they aren't really weird and worth talking about.
So I wanted to pick a couple that I think you probably have heard of, and then one that
you probably haven't.
So the first one that you probably heard of is Mimosa Putica, aka the Shy Plant.
And it has a pretty special defense mechanism, which you might know about, you might not
(01:58):
know.
It's a plant that grows kind of as a weed, it's quite a scragally little species, and it's
native to Central America, but these days it's found all over in kind of tropical and
subtropical areas.
It's a big genus that Mimosa comes from.
It's part of an even bigger family, aka, which is the legumes, which includes all beans
(02:18):
and peas.
You may know that the legumes are unique in the plant kingdom, performing a special symbiosis
with bacteria in the rhizovium genus, genus that are able to pull nitrogen from the air.
In its inert form, what we call molecular nitrogen, which is about 80% of the air around
us.
But unfortunately most plants, well, plants can't use nitrogen in that form.
(02:40):
They need nitrogen in an organic form, something like nitrate or ammonium where it's basically
the chemical bonds have been modified in a way that makes it kind of accessible to normal
biochemical processes.
And nitrogen is often really limiting for plants, so it's incredibly useful for legumes
that they have, these little bacteria, these rhizobia, that have some kind of biochemical
(03:04):
wizardry where they can actually pull nitrogen from the air and what we call it fixing, which
is like convert it into an organic form that can be used by the plant.
And in return, the plant provides a physical housing within the roots, like you can pull
up the roots of a legume and you'll find these little nodules, these little round balls
(03:25):
that are a little bit pink in color because of an enzyme in the bacteria.
And that's where they physically house the bacteria, so there's bacteria have like kind
of a good environment to grow in and they get a bunch of sugar from the plant.
And in return, the plant gets this leg up over all the other plants around it in the form
of an easy access to nitrogen.
So that's just another thing about legumes, that's not the specific thing to do for the most
(03:48):
aputica.
So the most aputica, defense mechanism we're going to talk about is not defending itself from
the rhizobia, but defending itself from herbivores.
And this is a defense mechanism that has been well known for I'm sure thousands of years
since as long as humans and this plant have interacted.
(04:09):
But actually, despite thousands of years of kind of human knowledge of this kind of
the existence of this mechanism, the details of how it works, the molecular level are really
going to, there's been recent breakthroughs and there's still quite a lot of open questions
about it.
And so if you don't know a lot about plants, you probably do at least know that they are
(04:29):
not renowned for their fast movements.
I actually think it's useful to think about plants as organisms that do move, but they
move via growing by growing in particular directions.
That's how they kind of reach out and access particular maybe nutrient pockets or better
sunlight or water, but it takes time.
(04:50):
So depending on the plant and the plant organ growth might take place over several hours
in the fastest cases or several decades in the slowest.
Normally it's something more in between over the space of days and weeks of active growth.
You've probably seen this like most of the time plants, they're not really look like
they're doing very much, but when growth is active, you know, particularly notable in temperate
(05:12):
regions in spring when new leaves are kind of budding and expanding, you can see very dramatic
growth over the space of a few days normally.
Yeah, but so that's in general plant movement pretty slow, but there are a few exceptions
when it comes to this and one of the most famous is the Venus fly trap.
And then another is the one we're talking about, the rapid folding of the leaves of the
(05:34):
mimosa pudica plant.
This pudica has a pineite leaves like many legumes and so you can go go go that but think
of it like feathers so they're kind of long leaves with lots of little leaflets all along
the side instead of like the individual fibers of the feather.
And all it takes is a single touch so you can go up to one of these plants, touch it and
(05:56):
one of its leaves and you'll see all the leaflets along that plant along that leaf folding
up and then that same process spreading within a few seconds to all the neighboring leaves
and all the leaves along that branch will fold up meaning instead of kind of being held
out horizontally they will droop vertically down.
(06:16):
And this is very dramatic, very obvious and visible and happens within the space of a
few seconds and that is pretty rare and unusual in the plant world.
Now this happens has been known for a while in a kind of physiological way, kind of like
in the sense that it's known that there's a little structure at the base of each leaflet
(06:39):
called a polvinais that looks like a slight bulge at the base of the stalk of each leaflet
and each leaf and you can see this if your eyes if you look at the plant.
And inside that polvinais are hundreds of cells that are very densely packed together
and under normal conditions they are pumped full of water which tells them very rigid and
holds the leaflet horizontal.
(07:00):
However, with the right signal proteins called aquaporins inside the membranes of those
cells are activated and that allows water to flow out of the cells quite rapidly and as
they lose water they lose rigidity and that polvinais suddenly like loses its tension
and the leaflet drops and then that's is a reversible reaction.
(07:22):
So you don't need kind of irreversible growth, it's something you can basically pump water
in or out of those polvinais cells and that's what allows the leaflet to droop or kind of
return to its rigid horizontal position.
It's also known or at least it was kind of assumed that it must be that there are some
receptors so specialized cells within the leaflets called mechanoreceptor cells that trigger
(07:48):
an electric action potential that can rapidly travel to all the polvinais in the vicinity
of the touch telling them to kind of close up shop.
And this is just because that's similar to how a venous fly trap works.
We know that plants have mechanoreceptors that normally they don't respond very quickly
(08:11):
but they are definitely sensitive to touch and they have these specialized cells to do that
and we know that plants can exhibit action potentials which action potentials are the
same way nerves work in animals.
Essentially there are proteins in the membrane of basically every cell where the animal
plant or other that regulate the flow of electrically charged ions and for any given
(08:33):
cell there's a resting balance of ions that is constantly actively maintained but under
certain conditions the regulator proteins change their state and allow ions to flow
in the opposite direction either by removing barriers that have held ions back or by using
energy to pump ions in a particular direction and that changes the electric charge of the
cell which itself is a powerful signal that can be detected by proteins in neighboring
(08:58):
cell regions and that that tells them okay you should open up the membrane channels,
the transporters and kind of perpetuate this signal.
And in plant sorry in animals we have these long specialized cells called nerve cells where
that action potential signal can pass along the whole length of the cell and we have individual
(09:22):
nerve cells that can go up like a whole leg they can be very very long and they have a
bunch of specializations kind of these around nerve cells that make them they allow the
action potential to propagate very very rapidly.
Plants don't have cells like nerves that are specially adapted to propagate action potentials
(09:45):
it's more every cell can propagate an action potential to some extent but they move slower
than in our cells so in the space of seconds instead of milliseconds but one of the things
that plant cells do have which facilitates instead of having you know one giant specialized
nerve cell that the action potential can propagate along the length of all the cells in an average
(10:10):
plant organ are actually interconnected with each other via tiny cell to cell linkages
so there's actual direct connections where the the membranes have fused and there's no
barrier in between the cells in very small little areas dotted around the connection surface
between the cells record those plasma desmitter.
(10:30):
Anyway these little connections they have a bunch of different functions in plants but one
of the things that they allow is for the fairly rapid exchange of ions between cells and
that exchange that kind of facilitates the movement of the action potential.
So that was this was already known were not sure at some point early 20th century I think
people found out that action potentials existed in plants as well as animals.
(10:55):
Okay so the piece of the puzzle that connects back to the listener question that has been
harder to pin down to now is why does my most apodica fold its leaves and this is something
that there has been some kind of recent research published on but there just was a complete
(11:16):
death of research scientific research published in this area till now and I think there's a
few it's kind of like worth reflecting on why and I think there's a few reasons one is
that plant science research is very expensive really any life science research these days is
very expensive it requires a lot of people require specialist equipment that all costs money
(11:37):
so research tends to be focused on things with real world applications that a lot of people
care a lot about and for plants that means overwhelmingly agriculture.
No one eats my most apodica to my knowledge so there's just not that much incentive for
anybody to bother investing a bunch of money into research into it and that means for the
(12:02):
vast vast majority of plants we know very little about them other than maybe the basics
of their morphology you know features like descriptions of their flowers enough information
that you need to kind of classify them and say okay we kind of know what type of plant
this is and how it fits into the plant family tree but there'll be you know the most plants
(12:24):
no one has ever done a kind of like a detailed biochemical analysis on their different cell
components and looked into their genetics and all sorts of different things that we have
the technology to do but it's like it takes time it takes money the most apodica we actually
you know have some research into I think probably just because it is such a cool fascinating
(12:45):
plant that has this feature that people are just quite interested in not interested enough
to want to pay a bunch of money for have a to support a bunch of research teams but enough
to maybe pay a couple of research teams around the world so now there's a little bit just
general plant science background but there has been some recent research that I wanted to
(13:09):
summarize so Takuma Hagarah and his colleagues from several different institutions in Japan
as well as the University of Wisconsin Madison published a data packed and fairly easy to follow
paper just a few years back in 2022 which I will of course link in the show notes and one of
the first thing they did was document a detailed experimental investigation into why the most
(13:31):
apodica has this rapid leaf drop and they from what I can see were the first folks to do so
in a scientific paper so to really say like why does the plant have this physiological process
you'd need to rewind evolution over millions of years and be able to chart all of the kind
(13:52):
of conditions in the environment of the plant that it was responding to through natural selection
or the natural selection was responding to we can't rewind evolution so we can do is kind
of make some reasonable guesses by seeing okay well what you know making some assumptions
about why do we think you know what do we think is the advantage for the plant and then test
(14:12):
those assumptions and so that's what they did they they already assumed that the reason
that the plant has this behavior we could call it is to defend it against herbivores
and so they were but they're still the first people to actually test that experimentally
to my knowledge and so they check this in a couple of different ways and one of the ways
(14:38):
they did this and I should have some sort of like GMO plaques on is that they made a genetically
modified most apodica plant which is quite exciting and it's also you know not to keep
digressing too much but I think this also is a good chance to check in on the fact that
most of the genetically modified plants that are produced around the world not in terms
(15:02):
of like total volume of plants but in terms of like all the different species that have
been genetically modified there's very few genetically modified species or varieties
that are for commercial application but there are tons and tons and tons made all the time
for research purposes and I know this because it's you know the sort of thing I used to do
most molecular plant science labs these days you know one of the tools among many they use
(15:29):
is genetically modifying plants to kind of ask questions about them so in this case they
use genetically modified and they use a thing called CRISPR which will learn about more
at the end of this season but basically allows you to kind of go in and break specific genes
within the plant genome and so what they did was knocked out is I know the technical turn
that you use knocked out the gene broke the gene that is crucial for the function of
(15:53):
the polviness and what this means in practice is it basically stops the plants from being
able to have this drooping effect and they also did the kind of stimulated the same thing
using a different method which is like a great piece of scientific technique is like make
sure you can ask the same question using two independent experimental methods just in
(16:15):
case there was something kind of like an unexpected side effect of your first experimental method
where you it kind of gives you a result and you think it's because of X but actually it's
because of some hidden feature of your experimental setup so it's good to like try to ask the
same question multiple different ways so they made this genetically modified version
of the plant they also just use a chemical that stops the polviness working and in both
(16:41):
cases they looked at how long potential herbivores in this case it was some caterpillars
and some crickets spent feeding on the leaves and they just kind of recorded that and were
able to show fairly clearly the plants that lack the ability to droop were basically had
their leaves eaten more it's pretty much as simple as that and it seems like quite a simple
(17:04):
experiment but it's like it does you do have to kind of do it carefully and make sure you're
really tracking it and and have these controls in place but for as far as I can see they were
the first to just say like yes okay maybe this isn't exactly why it evolved but we do know
that at least this drooping mechanism at least in a laboratory setting does reduce herbivory
on these plants so anyway that's something that was very cool another kind of cool defense
(17:31):
mechanism I wanted to mention but I'll just touch on very briefly so I can get to my like
favorite one is ant plants defense by ant so that's right there in fact hundreds of species
of plants mostly in tropical and subtropical parts of the world which have a mutualistic
symbiosis with ants mutualistic symbiosis meaning they living very very closely and intimately
(17:54):
together and each side benefits just like the rhizobial legumes symbiosis we talked about
that's mutualistic so is the ant and plant symbiosis depending on the species the plant might
provide a special structure that houses the ants so this is not just ants kind of like
happen to be near to the plant they live inside the plant most of the time and then in most
(18:16):
cases the plant also has a specialized organ that provides food there's this can happen
in various different ways but it's not like nodules little food packets so the plant produces
for the ants and in return the ants fiercely defend the plant against any would be predators
well herbivores they get too close and there's a fun word for this murmurco fights literally
(18:44):
ant plants but doesn't murmurco fights sound cooler so yeah go google murmurco fights and
look at some of the really cool kind of ant houses of these plants grow but in the interest
of time I will move on to the next one because otherwise this episode might be super long
I wanted to end this long answer to this still is still our first question with my favorite
(19:05):
weird plant defense mechanism the chameleon vine so you know chameleons these crazy lizards
that can change color to mimic their backgrounds and blend into their surroundings well in
2014 a bombshell hit the botanical community two researchers from Chile a nesto geonoli and
Fernando Carasco-Ura published a report of a tropical vine boughela trifoliata that unique
(19:29):
among all known plants can do what chameleons can presumably this property has been known
to those living in and around the native forests of this vine for a very long time but the
native rangers not that far like it was not known to that many people before and there
been no scientific reports published on it that can help you know one of the benefits
(19:49):
of a scientific paper is just a kind of way to easily alert researchers around the world
to something and so in 2014 they published a paper they're not just said okay the vine
exists the vine had already been described briefly before but what they showed was that
this vine has a chameleon kind of property rather than changing color what this plant can
(20:14):
do is that the leaves of this vine change shape and also their kind of texture and color
depending on the tree that they're growing on and I'm going to link the paper again in
the show notes so you can look it up and it is actually quite astonishing this is not like
a some super subtle thing where you have to kind of squint you're like okay I guess those
leaves are like maybe a little bit more round you know this is quite dramatic it's not a
(20:37):
perfect camouflage but it is pretty good and like it's so amazing that you can even have
one boughela trifoliata vine that happens over its whole length to be growing on three
different trees at different points along it's kind of main branch and and it will have
different shaped leaves at each of those points based on the tree that it is growing on so they
(20:59):
able to show this isn't like there's just some kind of variation in the morpho types of this plant
that's a fairly common thing that if you kind of have a field of plants within that field you
might find different versions with different leaf shapes no it's literally one individual can
have different leaf shapes and that if you experimentally grow the vine in a lab give it different
(21:21):
kind of host trees to grow on you can see that it does indeed adapt its leaf a leaf shape to the
vine that you give it even artificial vines that don't exist in nature sorry artificial host trees
and this kind of blue everyone's mind because there's just no precedent for this in the plant world
(21:41):
and so that was in 2014
and they did oh yeah a key thing i wanted to point out is that they also in the 2014 paper showed
that this does indeed reduce habivory so the kind of very similar to the previous paper they're
(22:03):
basically able to show that this property does reduce the amount of time the insects spend basically
it's what it seems like is that the insects notice the leaves less just like with a chameleon it can
kind of like blend into the background more and but they were not able to show how this mechanism
(22:24):
works and i would say like there's a couple of updates i'll give you but it's still very much an
open question i do not think it's been definitively solved at all and there was a couple of like
main approaches or like theories about this so in 2020 an american amateur researcher which i think
is really cool to shout that out because as these days it's very hard to kind of participate in
(22:47):
scientific research if unless you work you know unless you have a PhD and you're working within some
kind of a traditional institution but it can be done so there's an american amateur researcher
teamed up with a german researcher at the University of Bond to show that the vine will attempt to
(23:07):
mimic a plastic vine that it's grown next to and that they propose that this is due to plant vision
which is not as crazy as it sounds no one suggesting that plants can see like animals can
but plants can certainly sense and respond to light and what they're hypothesizing as that these
plants have specialized cells that are particularly sensitive to light and can detect basically roughly
(23:29):
the shapes of the leaves that they're growing near and then kind of there's a feedback mechanism
to recreate that shape which you know that ability to kind of basically see shapes would be unprecedented
but and they and they did not they did not find these cells they did not show that mechanism
they were more showing like well it seems logical because we can give it some shape it's never
(23:53):
you know encountered before in in its evolutionary history and it's still able to mimic that shape
so it must be able to somehow get information about the shape in real time and also it was a
plastic leaf it wasn't giving off any natural plant chemicals that might be you know the other main
theory is okay each of the different trees that happens to grow in the native range of this vine
(24:15):
has a certain kind of chemical signature to it so all the plant needs to do the chameleon vine
is detect that chemical signature and kind of like switch between its different pre-programmed
leaf shapes but that does not seem to be the case um and oh yeah and so another paper came out in
2022 so like this is all very recent stuff still very much ongoing question showing that there
(24:38):
seems to be some overlaps in the leaf microbiome of burky letrofoliata and its host trees
suggesting that microbes growing on the leaves provide a signal to the vine to start mimicking
and like like as I just pointed out that doesn't seem to stack up with the fact that it can also
mimic some random plastic leaf shape because the plastic leaves will not have microbes growing on them
(25:02):
or least it shouldn't and so it doesn't seem to make and also this other group with their kind of
hypothesis that something about the microbiome of the leaves they haven't got a mechanism for that
yet like this is still a very open question so if you're like wow chameleon vines that sounds amazing
get involved there's plenty of open questions there like I mentioned you don't expect to get a
(25:25):
bunch of government funding to study this because there's really you know no one eats this chameleon
vine with that said sorry to get on my soap box but you know this I think you know could end up being
a classic example of where basic research and something that seems very niche and obscure could
pay off because whatever it is there seems to be some totally novel kind of physiological mechanism
(25:47):
in this plant and if you can work out what that is who knows maybe it will have some really interesting
very practical applications but you don't know until you find out anyway so that
long rambling journey will wrap up question one for now okay questions two and three will not be quite as
long I promise okay the next question are darlie speckles like tulip distortions and caused by a virus
(26:15):
so I love this question from @fckisberglettis on instagram because it gives me a chance to talk about
ornamentals aka flowers which have some really interesting botany and history and if any of this
sounds interesting to you gonna have this stuff that I'm about to talk about you can read a lot more
fun flower stories the intersection of history and botany in flower confidential by Amy Stewart a
(26:38):
really enjoyable read I recommend it so but let's dive into it so the question has two parts it's
the the darlie speckles and are they like tulip distortions which is caused by a virus so I'm gonna
start with talking about the tulips because some of you may know about this but some of you probably
do not there are a lot of things to talk about tulips they have a lot of kind of juicy history to them
(26:59):
you probably know tulips they have these ball shaped richly colored flowers and their name in fact
comes from or the name in english from the turkish word for turban because the resemblance between
the flowers and they're kind of luxurious turban and that's you know particularly fitting because
they were introduced into europe from central aysia via turkey in the 16th century and by that point in
(27:22):
the 16th century the wild tulip flowers from central aysia have been selectively bred you know for a
long time in central aysia to produce beautiful ornamental flowers and so you know by the time they
arrived in western europe in the 16th century these were not you know the wild flowers this has
already domesticated ornamental and it really blew people socks off they people fell in love with
(27:45):
these tulips and in particular the dutch went crazy for tulips reaching a peak known as tulip
mania in the early 1600s so this is about 400 years ago and it was you know within a century of tulips
first arriving in western europe like it was they were a pretty overnight sensation tulip mania
all kind of peaked and already was we'll see collapsed within the space of a century
(28:11):
i am not sure where the cause and effect lie but ever since tulip mania so around that kind of like
early 1600s the netherlands has been a global center for floriculture meaning the cultivation
and trading of ornamental flowers and they are still the global leader in that industry i don't know
quite what it is whether tulips are really anything to do with it or it's kind of like they're just
(28:35):
another symptom dutch people and floriculture seem to just really go together um so tulip mania
wasn't just a name for a craze but refers is normally used to refer to a speculative bubble that
happened kind of towards the end of this period of intense interest in tulips as people started
to trade tulip bulbs are higher and higher prices and in a way that resembled a stock market
(28:59):
where they weren't even often literally trading the bulbs but just kind of on paper trading the bulbs
are higher and higher prices until as tend to happen one day that speculative bubble burst
as people realized like okay the values were trading has really like these are just some flowers
and actually one of these values based on and people completely lost confidence overnight
(29:21):
and people lost their fortunes overnight and it's a very famous event in history of economics
as a really early example of the sort of speculation that you see in stock market bubbles
that then lead to crashes um but i'm not gonna go too much into the economics i just wanted to talk
a little bit about tulips like one of the things within tulip mania um which was
(29:43):
the most valued tulips were those that had streaks of yellow and white in kind of wild irregular
patterns in the petals which are known as um broken tulips and the way that this works is that these
plants as was unknown at the time this was actually just kind of something that people
(30:04):
researchers realize in the 20th century those plants were infected with a virus
could which you know when it was discovered it was named tulip breaking virus because of this property
and that where the virus kind of as it spreads through the flowers and the different cells of the plant
it removes color from the infected cells and so it creates these wild patterns this kind of
(30:30):
variegation but it also it doesn't just like oh it makes the flowers look cool it does but it also
does weaken the plant and it you know you probably know that tulips have bulbs where kind of they'll bloom
and then they'll basically kind of look like they shrink back into the bulb for another season
the bulbs weaken over time with the tulip breaking virus so they don't have an indefinite
(30:55):
lifespan anymore they will die after a few generations which is why today there are very few
truly virus broken tulips in cultivation there are i mean if you for example happen to live in the
Seattle area like i do and you know that just north of us in scadget valley there's a famous
(31:17):
tulip festival and you can see all these different kinds of tulips you'll see plenty of examples
of ones that have like streaks of white or yellow in the petals that sounds like this tulip breaking
virus it's not the same thing so those ones that you can get commercially they have in fact been
just bred through traditional plant breeding methods which we'll learn more about in upcoming
(31:38):
methods episodes in order to achieve that stripy pattern i did for a little bit of digging
found out that there does seem to be one truly virus broken tulip variety that is still
commercially available although it's hard to get your hands on it's called tulip absalon that's
(31:59):
like the name of the variety and i got to say from the pictures it looks really really gorgeous
and i would love to get my hands on one it does i got to say it looks cooler than the the streaky tulips
that are bred with conventional plant breeding methods so in january 2025 research is one
(32:22):
carerro and hillon at the University of Alberta like that sorry stop go back so i'll just end on
or this kind of tulip section by saying that in january 2025 so this year you know this is
uh i can mention tulip breaking for viruses was this thing that was first noticed four centuries
(32:44):
ago and there's take until this year for someone to even propose a model of what they think
might actually be going on it's like okay we know there's a virus but how does it produce these
particular patterns and they basically it's these researchers one carerro and hillon at the
University of Alberta proposed a mathematical model that could account for the pattern of the
breaking on the petals and why the virus would create that specific infection pattern and so
(33:09):
like you know i'm not going to go into all the details of that but i'll link the paper in the show
notes to just a show like just because people can see a phenomenon doesn't mean that we know
why it works even something that you know i know maybe not everybody in the world knows about
tulip breaking virus and like the tulip may be it but it's reasonably well known pretty like
famous thing within botany and there's still a ton of open questions okay now dali is
(33:37):
dali is like tulips grow from seeds yes but also from underground structures tulips make bulbs
which are underground storage organs that exist that consists of a shoot apical meristem surrounded
by specialist leaves very much like an onion so onions are bulbs tulip bulbs are bulbs
(33:57):
very like analogous to each other if you slice over an onion or a tulip bulb they all look very
similar um dali is make tubers the same sort of structure as potatoes tubers are flessy pieces of
root or stem they contain a lot of carbohydrates to store energy and have lots of smaller meristem
(34:18):
from which new growth can emerge so the structures are a little bit different but similar and effect
underground storage organ there can be dormant and then new growth will emerge when planted normally
in spring while tulips are native to central Asia dali is our native to mexico and central america
from my understanding dali is have long been cultivated in the region uh mexico central america
(34:43):
as a food crop um yes dali are tubers are edible so are tulip bulbs in fact eating tulip bulbs that
had piled up during the second world war was part of how Dutch people survived a forced starvation
imposed by the Nazis in the winter of 1944 unpleasant episode um but back to the dali is pretty much
as soon as europeans started colonizing the region of mexico and central america they were taken
(35:07):
by the beauty of dali is and built on existing substantial diversity in varieties to create more
and more ornamental varieties of dali which has really just continued ever since um dali is
are maybe not quite in the same league as roses in terms of share of global flower market but they are
definitely you know one of the heavy hitters and they have very passionate fans um probably unsurprisingly
(35:33):
dali is are the national flower of mexico more surprisingly given the total lack of historical
connection they are the city flower of seattle as far as i can tell uh you know i tell me you know
let me know if i'm wrong about this there was a nationwide craze for dali is across the us in the
early 1900s including in seattle but it's not limited to seattle but seattle was hosting a world's fair
(35:56):
in 1906 and didn't have an official city flower not the city's need an official flower but you know
didn't have one yet and some some local dali are lovers for the an official declaration making dali
as the city flower would be a kind of impressive show of seattle's cultural sophistication ahead of the
world's fair um and you know mostly that that has not meant very much for seattle um unlike you know
(36:20):
portland is city of roses there portland origen you'll find tons and tons of roses around the city
kind of rose iconography you don't see a bunch of dali are iconography around seattle um but there is
a dali as show garden in seattle's volunteer park with different dali are varieties the bloom in
august which is the normal time for dali is and it's absolutely gorgeous so if you happen to be in
(36:43):
seattle in august go to volunteer park check out the dali garden it's lovely um something else that
I learned when researching this there is a town in the Netherlands just to go back to much dutch
people love flowers who did not want to miss out on the floral action with dali is and since 1936
has hosted a dali parade and this is not just you know some okay there's some flowers and you
(37:05):
kind of like goes through the streets and people hand out flowers or something no this is a pretty
big deal it's the town of sunda not sure how to pronounce that correctly even though I do have dutch
heritage do you not know how to speak dutch um but so it's the town of sunda but all the local villages
around this town compete by creating massive elaborate floats decorated entirely with dali is and
(37:29):
the dali is they grow themselves and apparently you know according to the internet each year apparently
about six million dali is a grown and used in the parade floats and I really recommend just like
look up some pictures of this online the floats are really cool the parade is called the bloom and
course so it's in it but I think if you just go called dutch dali a parade you'll get it um so I'd
(37:50):
recommend that these days there are probably thousands of distinct varieties of dali is and by
varieties I mean distinct genetic lineages and the aesthetic diversity of dali is is much greater
I would say than for most ornamentals there are different varieties of dali is that just you know
to have first glance don't look like they're from the same species at all um and there's certainly
(38:16):
this diversity a lot of it has come from small time breeders working in the same sort of way as
people have done for centuries so we're learning upcoming episodes about some of the more modern plant
breeding approaches and methods that have been developed in the 20th century and 21st century
you know particularly obviously we'll get to gmo's but we'll learn about some other stuff along the way
(38:39):
um but there's also what people have done for a long time which is plant a bunch of different seeds
make kind of crosses by transferring pollen between plants and kind of just like see what you end up
with and one of the great things about dali is is because they produce these tubers the tubers basically
(38:59):
allow you to they there's no kind of production of seed and transfer of genetic material between
different parents that goes into producing a seed it's just a clone like the tuber like with potatoes
like the tuber is just a piece of the adult plant you can in fact take the tubers break them apart
into smaller pieces and propagate basically clones of that same adult plant so once you get like a nice
(39:23):
dali a variety that has beautiful flowers that you love you don't risk kind of losing it again
as it interbreeds with other individuals you can just propagate that dali are through tubers indefinitely
that also make dali as excellent candidates for mutation breeding which we'll learn about
um the next in two episodes time um but it's basically deliberately exposing plants than
(39:47):
mutagenic radiation or chemicals that are mutagenic which modifies DNA sequences randomly um
and you can do this you're gonna take a dali attuber like break it into hundreds of small pieces
expose it to this mutagenic radiation or chemicals and then and then kind of let those tubers like
plant them see what the flowers look like and there's a good chance you'll get at least one that
(40:09):
has some new interesting flower phenotype and then you can start propagating that in haypressedo
you've got your new dali a variety um and so you know there's that's mutation breeding has been
particularly successful in the dali a breeding industry so let's connect this back to the original
question like tulips that are varieties of dali are with variegation meaning stripes and dots
(40:33):
in the flowers that lack pigment or have a slightly different pigment and unfortunately sort of
short answer to this is it seems as far as I can tell there is no viral infection that causes this
it's just one of the many many different varieties that popped up as people have been breeding daliers
they are just genetic variations so sorry I could have answered this question which is a simple no
(40:55):
but where would be the fun in that and I'll link some of the references that I was drawing from in
the show nights okay let's do a final question can we GM a mango so that it has edible skin like an
apple so I want to thank mechanical bees on reddit for this question can we GM a mango so that
(41:19):
has edible skin like an apple this time I'll start with the short answer probably yes
um so let me share some my thinking about this firstly what is it that makes the mango skin kind
of unpalatable there are a few different pieces this when it's quite thick uh like quite physically
(41:40):
difficult to eat so that would be one issue then it's just quite bitter and then kind of sub sub
bullet point of bitter there's a specific bitter compound in this peel called ursial or
jury ursial um which is particularly problematic it is named for the Japanese name for the lacatry
(42:06):
and lacatries and mango trees are in the same family that the anarchy de ac a most of the plants in
this family produce ursial in some of their organs the family includes cultivated plants like mango
cashew and the lacatry which is used to make true lacca using um Japanese lacquer wear the family
(42:26):
also includes poison ivy poison oak and poison sumac and so that might give you a hint about the
problem here ursial um irritates skin by triggering an inflammatory immune response or what we call
an allergic response in those that have sensitivity this is uh potentially life threatening for most
(42:47):
of us who are not kind of hypersensitive to it it's just annoying and a bit painful um so that
hypersensitivity when we say allergic we actually mean a hypersensitivity but a allergic reaction just
means it triggers an irritation that is based on an immune basically a gentle immune response
that's an allergy is kind of an inappropriate immune inflammation um and um yeah everyone pretty much
(43:18):
everyone gets it to some extent both for poison ivy and for mangoes um and but the mount in mangoes
is kind of less problematic and this specific there are kind of different versions of ursial
um and the one that is in mangoes is one that tends to be less irritating um triggering less
(43:40):
triggering of allergic reactions than the one that is in poison oak um so that's why mangoes tend
to be less problematic for people but the the chemical is particularly concentrated in the peel
so for most people you know the amount that you get exposed to just from eating the fruit of the mango
isn't enough to cause much of a reaction maybe like a slight tingling people who have
(44:02):
uh what we call like in everyday speech and allergy to the mango it can there's a whole range of
how sensitive they are but for most people if you ate a whole mango peel you would not enjoy it
you would have some sort of unpleasant irritating reaction um
(44:23):
so if you were to make a mango with a peel like an apple that you'd want to eat you would need to do
quite a lot you'd want finne a skin that is less bitter but you definitely want
to get rid of the ursial so i found a paper in 2020 that they published the mango genome
it was led by a large research team in hyena and china and as part of the work they looked at
(44:45):
transcription so that's gene expression in different tissues and they pinpointed a set of genes
that are encode enzymes called chalcon synthases um and particularly they found the chalcon
synthases that are expressed more in peels and just based on what we know about the functions of
similar enzymes known from known from other plants they're pretty sure that these are the enzymes
(45:09):
that are responsible for making the ursial and the peel um so if i wanted to make a transgenic mango
that had peeled that was more palatable one less irritating what i'd want to do is knock out or break
those specific chalcon synthase genes in the mango and now that we know what those genes are
it's a lot easier to do because in that we'll we'll dive into all of this when we explore how you make
(45:33):
gmose but obviously you kind of have to know what you want to add if you're trying to add in new genes
or what it is you want to break or modify in the existing genome like if you don't know that you
don't have any way to begin your project so knowing that is not everything you need but it's a very
important first step um bigger problem that i can see is that no one seems to have made a transgenic
(45:59):
mango meaning an adult mango tree that has had its genes modified using laboratory methods um
like many trees uh mango is hard to do breeding with and most mango varieties around the world are
random mutations that appeared and then cuttings from the tree have been cloned over and over kind of
(46:19):
just like you can take um tubers and break them apart and grow new darlias from them with a lot of
fruit trees you can just take various pieces of the tree and with a little bit of gentle coercion
and sometimes a little bit of chemical help you can get those little pieces of tree those cuttings
to grow into full adult trees and that is how most fruit trees are propagated not from seeds but
(46:43):
from cuttings of adult plants um and that's great in some ways but it also means it's hard to do
breeding with those trees that's how to create new varieties um we will see that making a
transgenic plant takes a lot and mostly involves grinding the plant into cells and using one of a few
methods to get DNA into those cells and then getting the cells to turn into adult plants and those
(47:07):
steps can be very easy for some plants and seemingly impossible for others and i suspect for
mangoes it's both difficult but also just not something that anyone is pouring tons of money and
attention into is the bigger problem so like a method of how exactly to do this for mangoes is lacking
mango is a big crop um you know it's not it is pretty commercially successful all around the world
(47:32):
but it doesn't come close to the global market value of staples like rice and potatoes so there's
just not as much economic and sensitive to bother trying to work out how to create transgenic
maven goes so that does not mean that it is impossible um but let's just say maybe it is impossible
and we can't for some reason just the normal methods that have worked for many other plants just
(47:55):
won't work for mangoes we cannot genetically modify them then you'd have to rely on conventional
breeding but mangoes like as i mentioned kind of basically all fruit trees are propagated by cuttings
not seeds um because in you know to dive into this a little bit more the seed will not give you a
tree that looks like the mother tree that produced the fruit it came from the seed has a combination
(48:18):
of maternal and paternal genetic material the fruit around the seed just comes from the mother
and so the you know you may and generally the fruits are what we're interested in but this you know
all the other organs of the tree come are what we call the other mother and then the father tree
just gives its pollen um and just to like i know i'm kind of complicating things in case you're
(48:42):
wondering like there's mother and father trees most trees most plants are um hematoricitic they are
they produce male and female organs some aren't sometimes particularly with fruit trees you do
sometimes get male ones and female ones and you'll see only the female ones produce fruits
the male ones just produce pollen anywhere there's a bit of a but in general you know the seeds
(49:06):
are the end result of that sexually production the seeds will have a combination of genetic variation
from both parents and so will not look like the mother tree um and so that can be you know if you have
a variety of mango that uh is great um and you love the fruits that it produces you want to just
(49:26):
reproduce that plant via cuttings to always make sure you get identical fruits every time
um and we'll we'll learn more about that in the coming episodes if you're like wait that was too much
and i'm confused um and so if you're wondering like is this just an issue for fruit trees no it's an
issue for all plants but in most crops where conventional where breeding based on sexual production is done
(49:51):
um this problem has been evaded by deliberately inbreeding plants for many many generations
so the point where there is no genetic variation or whatever genetic variation is there is the genetic
variation you kind of want and are controlling um but that takes many generations of inbreeding
(50:12):
which is fine if you have like wheat which you can actually get two generations out of it in a
single calendar year with the right coaxing you can breed you know you can inbreed that wheat
ten generations in five years but a mango needs many years to get from seed to sexual maturity um so
(50:34):
it's just like slow and painful to use that kind of method and that's where just in general this is
true for all fruit trees trying to do conventional breeding with them is slow and painful to give an
example there's this new apple variety the cosmic crisp that was released in Washington state in 2022
I think it is more widely available these days I'm a big fan of it um it took a huge team of agricultural
(50:58):
scientists 22 years to make this one apple variety that is essentially just a cross between two
prior apple varieties um so it's it's far harder to breed new tree fruit varieties using conventional
breeding methods uh and the same I'm sure is just as true of mangoes people are breeding mangoes
(51:21):
it is there are teams of people around the world doing this it's just like slow and painful and like
it said there's not as much economic kind of interest around mangoes so there's not as much effort
going into it um and there are you know also to point out that all are already many different
varieties of mangoes that exist it's not a kind of urgent pressing problem um but as we'll see kind
(51:46):
of in the coming episodes there's all sorts of reasons why even when you have like a perfectly
good variety of a plant you always kind of want to create more and have more options on the table
particularly in case there are diseases that come up that threaten the existing varieties
um okay anyway so plant breeding could be an option it's going to be slow and painful but it could
(52:06):
happen if people really would have determined to get a mango without a ratio in its uh peel and there's
a precedent for this that I thought was a fun opportunity to bring it up that was a pretty um actually
there's like quite a lot of interest in breeding out unpleasant chemicals from plants in the 20th
century and one of the most successful examples of this is canola which canola is brusica wrapper
(52:30):
that's from the mustard family um and it is like as long been known for its oil that comes from its
seeds but that oil was more just used in an industrial lubricant or for other kinds of purposes not
for eating because it's very very bitter naturally because of a chemical called a ruchic acid
and some researchers in the mid-century in Canada were like we are not going to settle for that
(52:57):
we think there's a lot of this plant grows really well in our climates and our soils
um and if we can just make this this oil edible it could be an amazing oil plant
for you to make cooking oil or you know eating oil and what they did was use chemical breeding methods
to completely eliminate the ruchic acid or to get it to such low levels that it's not bitter anymore
(53:21):
and it is perfectly edible and pleasant um and the product of that breeding was the kind of plant
and and oil that we now call canola and this is like fun bar trivia fact that canola is a acronym
that stands for Canada Oil Low Acid so the the plant is brassica wrapper but the particular
(53:44):
variety that is that can be used in cooking is called canola uh I think both because um you know
you wanted to have like a nice marketing gimmick like indicator this is a new product this isn't
the same old brassica wrapper that you know but also because the conventional name for brassica
wrapper in English at least as a um as a crop was rapeseed and that is actually still how it's mostly
(54:08):
known in the UK and in some other areas but like rapeseed you can imagine is not as a name that has
unwanted connotations um and so canola just sounds great um and so canola is what's used more in
North America um anyway so that's like there's precedent there for the sort of you know you could
imagine following a similar approach to get rid of the original in the mango peels um but we
(54:34):
that's not been done yet so in the meantime what do you do with all that is guided mango peels
researching this I did find some papers by researchers such as dv's sudakar at indian agricultural
research institute in New Delhi developing methods to take discarded mango peels from mango
processing and extract usable chemicals from them to reduce food waste and just as a reminder
most crops don't make it to the end consumer in an unprocessed form so there's a lot of waste
(54:59):
that builds up in the processing of plant products uh and it can be like um uh great to see like
what can we do with that how can we make sure that that um doesn't just go to waste and pile up
and decompose and release methane gas which is a powerful uh greenhouse gas um so just a shout out
(55:20):
for all of those diligent workers working on these not very glamorous questions like how can we
processing great valuable products out of mango peels um and and yet just to kind of remind you
that the original question was about like could we GM a mango peel a GM mango to have a edible peel
I think yes you'd have to get that genetic modification method to work which would probably just mean
(55:45):
like testing out a bunch of parameters until you get one that works and then we kind of know
which target genes would want to go after I think it would be doable I just doubt that anyone
would be that motivated to do it um but we'll see uh be really be very fun to see that in a few years
edible kind of mangoes you can eat like an apple coming onto the market um okay so I think I'll wrap
(56:07):
up here because I think I've been talking for a pretty long time um if you hated this don't worry
we'll be back to a regular scripted narrative episode after a two week break so I can catch up with
writing and recording if you liked it let me know I could definitely do more Q&A episodes based
on your interest dear listener until let me know by emailing Orlando@modifypod.com or that's Orlando
(56:30):
at modifypod.com or you can find my socials at modifiedpod.com that's the website that's also where
you can find the show notes and just as a reminder I'm Orlando D'Alanj this is modified as always
please do subscribe leave a review and tell a friend if you're enjoying the podcast and I hope you'll
We'll tune in again soon, bye!
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