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[♪ INTRO]
It’s pretty fair to say that people love
bread.
And cookies, and pasta.
And beer.
So it’s unfortunate that billions of dollars
worth of wheat, barley, and other grain go
to waste every year due to a fungus called
Fusarium graminearum.
The fungus produces toxins that cause a disease
called Fusarium head blight, or FHB.
The family of fungal toxins that cause FHB
mess with protein synthesis in all kinds of
organisms, including plants and humans.
This both shrivels the grain and sickens people
who eat it.
One of these toxins is sometimes known as
vomitoxin -- we’ll let you guess why.
It can also cause dizziness, headache, and
fever.
People have been dealing with FHB for thousands
of years, and it’s very much still a problem.
In a 2020 study, however, scientists made
a discovery that could help.
They’ve identified a protective gene in
a wild species of wheatgrass called Thinopyrum elongatum.
Researchers were already aware that this plant,
which is native to Africa and Eurasia, is
resistant to the blight.
The researchers sequenced the wild wheatgrass
genome, but that was just the start.
They systematically bred the resistant wheatgrass
with other plants and compared the DNA of
the various offspring with resistance to those
that weren't resistant to the blight.
Eventually, they identified a gene called
Fhb7, which codes for an enzyme that breaks
down the fungal toxins before they can cause
any harm.
Now, the way you’d expect this to happen
is for a gene that plays some other role in
the plant to eventually evolve the ability
to detoxify the FHB toxins.
Except it’s not what happened here, at all.
The Fhb7 gene appears to have made the jump
to plants… from another fungus.
The researchers found that Fhb7 is 97 percent
the same as a gene in the fungal genus Epichloë,
which lives on grass.
And it’s not present in any other grass
genomes outside of those in the Thinopyrum genus.
If Fhb7 had originated in plants, then it
would exist in other species that share a
common ancestor with Thinopyrum.
They don’t know how it happened.
But they think that the gene somehow slipped
from Epichloë to the grass about 5 million
years ago via what’s called horizontal gene
transfer.
That’s basically when one species somehow
acquires genetic material from another, even
though they can’t reproduce with one another.
Scientists know that horizontal gene transfer
happens pretty regularly in bacteria and other
simple organisms, but it’s less clear how
often it happens
in multicellular organisms like plants.
What Epichloë is doing with this gene is
uncertain.
The researchers think that it might help the
fungus compete with Fusarium to colonize wild grasses.
Whatever its original function, the gene seems
to have given the plant an edge in dealing
with fungal threats.
And here’s the incredibly convenient thing:
If you were an agricultural researcher looking
to solve the problem of FHB, you might want
to genetically engineer a gene like Fhb7 into wheat.
But nature’s already done that for us.
All researchers would have to do is cross
Thinopyrum with commercial strains of grain.
In fact, the authors of this study have already
done so on a small scale.
Now, researchers are hoping to take this finding
one step further and identify other, similar genes.
Then they could breed crops with several of
them at a time to make them even more resistant to the blight.
All in all, this is one natural feat of genetic
engineering that bodes well for the future
of bread, pasta, and all of that other good
stuff.
This gene came from somewhere totally unexpected
-- and that’s why it helps to draw from
a bunch of other different fields when trying
to understand the universe.
Brilliant’s new course Math History will
help you learn math alongside the people who
invented it -- their mistakes, their breakthroughs,
and their questions that remain unanswered
to this day.
Math and history, together at last!
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[♪ OUTRO]
