Dr Michelle Dickinson: nanotechnologist on scientists teaching lettuce to make its own meat protein

The world of meat alternatives could be about to change after new research published in the journal Frontiers in Plant Science came out this week. 

Instead of trying to make plants taste more like meat using flavourings, they've taught plants to manufacture myoglobin, the same protein that gives meat its distinctive colour, flavour and nutritional value.

Myoglobin stores oxygen inside muscle cells, but it also gives meat many of its defining characteristics. It contains iron-rich heme molecules that contribute to meat's red colour, metallic taste and savoury "umami" flavour.  

In plants, chloroplasts are the structures where photosynthesis happens, converting sunlight into energy. 

Chloroplasts are also excellent protein factories which carry multiple copies of its own DNA. 

That means if you insert a useful gene into the chloroplast genome, the plant can produce very large amounts of the corresponding protein.  

The researchers used a gene gun where tiny gold particles were coated with DNA containing the pig myoglobin gene and fired into the leaves of young tobacco and lettuce plants. 

Some of those microscopic DNA-coated particles entered the chloroplasts, where the new gene became incorporated into the chloroplast's own circular DNA.  

The transformed plants were then grown to maturity where they flowered, produced seeds and their offspring inherited the new gene 

The scientists crushed leaf tissue from the mature plants, separated all the proteins using gel electrophoresis, and then used an antibody test called a Western blot to specifically detect myoglobin which showed up in both the tobacco and lettuce plants. 

Myoglobin only works properly when it contains a heme group, an iron-containing molecule that sits in the middle of the protein. 

The researchers found that only around 35 percnet of the plant-produced myoglobin contained heme, compared with around 80 percent for myoglobin produced in bacteria. 

The plants were making the protein successfully, but many of the molecules were still missing their iron-containing centre. 

That tells scientists where the next engineering challenge lies and future versions will likely focus on helping plants load more heme into the protein.  

Despite producing large amounts of myoglobin, the plants grew normally, flowered, produced seeds and remained fertile which is an encouraging sign if this technology is ever scaled up. 

We could have a future where large quantities of leafy crops could be grown in fields and the myoglobin extracted and purified before being added as an ingredient to plant-based meat products, improving their colour, flavour and nutritional value. 

The researchers also speculate that one day, if regulators approve it, specially engineered lettuce could even become a source of heme iron itself.  

So does it taste like meat? We don't know yet. The researchers didn't cook burgers or run taste tests. This study was about proving that plants can manufacture the protein in the first place. The next challenge is increasing the amount of fully functional, heme-containing myoglobin before testing whether it really improves the flavour of plant-based meat. 

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Episode Transcript

Speaker 1 (00:06):
You're listening to the Sunday Session podcast with Francesca Rudgin
from News Talks EDB.

Speaker 2 (00:13):
It is time to talk science and with her science
study the Week, doctor Michelle Dickinson joins me. Now, good morning,
Good morning. You got an unusual one this morning.

Speaker 3 (00:23):
I read this and I was like, there's one experiment
I wish they did and they didn't. And I almost
got to the end of this journal, I was like,
I can't believe I read this and you didn't do this. Anyway,
it is published in the journal Frontiers in Plant Science,
and scientists have just taught letters to make their own
meat protein.

Speaker 2 (00:40):
But I just I can't get my head run this once.
So you're going to talk me through this one.

Speaker 3 (00:44):
Slowly, so many things anyway. Look, I am a meat eater,
so I am not one of these meat alternative people.
But those who are, You've got your veggie burger equivalent,
say it doesn't and if they ain't meet before they've gone,
it doesn't taste the same. There's something about it. They've
tried the texture, they've tried everything else. The thing that
is missing is something called myoglobin. Myoglobin in protein stores

(01:05):
oxygen inside a must or cells, and it's basically what
makes meat taste so great. It's got an iron rich
he molecule that is the red color and meat the
metallic place that tastes that savory umami flavor. It's the
thing that vegetables just don't bring it to you. And
so these scientists went, I wonder if we can make
vegetables create this meat rotein.

Speaker 2 (01:27):
So they did.

Speaker 3 (01:28):
Basically, they found that chloroplusts are excellent protein factories. And
so what they did is they use what's called a
gene gun, which literally is what it says. They basically
took tiny gold particles coated with DNA, which has the
pig my globin gene, and they just fired it willingly
at the leaves of young tobacco and lettuce plants, and

(01:48):
some of this DNA entered the chloroplast. A new gene
became incorporated into the m DNA of the lettuce or
the tobacco plant. And then these plants were grown to maturity,
they produced seeds, and then their offspring inherited this new
miglobin gene, producing chloroplast. So then they've got this whole
group of like daughter and plants that are producing pig

(02:12):
myoglobin right, So they crushed the tissue, they prove that
it had the miaglomat in there. They were like, cool,
now we've got pig meat producing letters.

Speaker 2 (02:20):
My gosh, right, so bad.

Speaker 3 (02:22):
And they were like, well, let's just make sure that
this is working. But actually the thing that gives it
the meat. He tastes this heme that's captured in the
middle of this protein. And what they found is actually
only thirty five percent of these had had the heme
in the middle, so it probably isn't going to taste
as meat as you would like. So they go, okay, well,
next thing we've got to do is make sure that
they can capture the heme better. So there's work to do.

(02:44):
But basically my big question in this was does it
taste like meat? Is this a pork like lettuce? And
they never tasted it. Oh, And I was like, well,
what is the point in the study exactly? How did
I read all ten pages of this research? And nobody went,
let's just try a leaf?

Speaker 2 (03:01):
Did it work?

Speaker 3 (03:02):
So I don't know how it tastes, sorry, but it does.
The theory is out there and basically it says we
could produce plants that have this Miclobeen in there. Maybe
you don't want to eat a pork tasting lettuce, whatever,
but you could then crush that up and put that
into some of these meat alternatives and maybe they would
taste more meating. But it was really disappointed that I
got through this whole study.

Speaker 2 (03:23):
But I think they've gone a little way to go.

Speaker 3 (03:24):
But lettus, I mean, maybe we're growing this life.

Speaker 2 (03:27):
Well, there's a lot of people out there that go,
you know, you get to the end of sumthing and
you go on another piece of littus.

Speaker 3 (03:31):
Yeah, maybe it's your protein into and maybe for people
if we're thinking about how do we get more protein
into people, this maybe this is a way of sneaking
in crushing up some let I'm not sure keeping out
for that crushed up litters.

Speaker 2 (03:44):
But what I liked.

Speaker 3 (03:45):
About it is this gene gun. I'd never heard it before,
and like you just blast certain cells into another plant
and you just go there you go, and it took
it out a boom.

Speaker 2 (03:53):
Thank you so much, Michelle.

Speaker 1 (03:55):
For more from the Sunday session with Francesca Rudken, listen
live to Use Talks. It'd be from nine am Sunday,
or follow the podcast on iHeartRadio,