What Makes Durian Fruit Smell So Bad?

Durian fruit is prized as a delicacy and staple -- and it smells like rotting. Learn how a group of cancer researchers mapped its genome to get to the bottom of this stench (and hopefully find something medicinally useful) in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain stuff from how Stuff Works, Hey, brain Stuff,
Lauren vogel Bam. Here in Southeast Asia, the Durian is
called the king of fruits, but not everybody in the
world bows down to this bulbous, spiny, custardy delicacy. That's
usually because of the odor. The smell of a ripe
Daurian has been compared to sweaty socks, road kill, custard,

(00:25):
rotten eggs, garlic, cheese, a gas leak, and a sewer
full of rotting pineapples. And it's strong enough that in
places where it grows, many businesses and public areas have
pictographic signs up no Duryan, like no smoking, but with
a spiny ball in the place of the cigarette. But
still the fruit has its super fans, and now some

(00:46):
of those super fans, from the National Cancer Center Singapore
and Duke and US Medical School, along with some financial
donors who love Durians enough to privately fund study about them,
have completely mapped the Dairyan genome to find out, among
other things, why the putrid stench durians. In the study
published in the journal Nature Genetics, the researchers sequence to

(01:08):
the genome of a popular and prized daurian variety called
Mussang King and found its genome is made up of
around forty six thousand genes, just about double the number
of genes that compose the human genome. They found the
plant is closely related to both cotton and cacao. That's right,
the plant that gives us chocolate. But the researchers were
really interested in the source of the smell, so in

(01:30):
snooping around the genome for odor producing compounds, they found
a class of genes called m g l S that's
methionin gamma liaises in the leaves, roots, and fruits of
daurian plants. The researchers found that these genes regulate the
synthesis of odor producing volatile sulfur compounds or vs cs,
you know like rotten egg smell. They also discovered that

(01:52):
in the ripe fruit, the expression of one of these
VCS expressing genes is about two thousand times stronger than
another part to the plant in the wild, This aspect
may be responsible for attracting seed dispersing animals like elephants
and bats to the Durian fruit. This isn't the first
research conducted on the durian's unique scent. In a team

(02:13):
of German researchers identified dozens of chemical compounds that combine
to create the smell, but that research did not investigate
the genes behind those compounds. The current research team was
hoping to make an important medical discovery with the sequencing
of the Musang king genome. After all, anti cancer drugs
like taxol derived from the bark of the Pacific u
save lives every day, and as biodiversity decreases all over

(02:37):
the world, we need to figure out what we have
while it's still around. But as Durian enthusiasts, these scientists
also just wanted to investigate how this quirky and controversial
plant might be conserved. Besides Mussan king, there are around
thirty other species of durian, both edible and inedible, in
the Southeast Asian forests, and some of them are endangered.

(02:57):
In a press release, co lead author doctor Ben Tian,
Deputy Director of the National Cancer Center Singapore, wrote, many
of these other Durian species are in this part of
the world, and sadly some are endangered due to the
increasing loss of biodiversity. DNA sequencing is thus an important
tool to protect the precious information contained in these fascinating
and important plants. Today's episode was written by Jesselyin Shields

(03:25):
and produced by Tyler Clang. I've got another podcast called
food Stuff that explores the science and history of food,
and we did a whole episode on Durian, so check
that out if you're still curious, And of course, for
more on this and lots of other topics about questionable smells,
visit our home planet, how stuff works dot com.