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Scientists have discovered that the silverleaf whitefly —
a pest that demolishes crops worldwide — stole a gene
from the very plants it consumes millions of years ago.
This stolen gene probably gives these pests an incredible superpower:
the ability to safely munch on whatever plants
their little insect hearts desire.
That’s because the gene codes for a protein that neutralizes plant toxins.
The team believes it’s actually how the plants keep from poisoning themselves!
And this is the first well documented case of horizontal gene transfer
between a plant and an insect!
Plants and insects have evolved alongside each other
for over 400 million years now.
And during that whole time, there’s been conflict.
The insects often want to eat the plants.
The plants don’t want to be eaten.
It’s a whole thing.
Of course, plants can’t exactly run away from hordes of hungry bugs.
They’ve had to evolve other defenses.
And one strategy that works fairly well for them is to produce toxic substances.
That way, any insect that tries to eat them gets poisoned.
Phenolic glycosides are especially prevalent in plants worldwide.
These potent toxins interfere with the growth, development,
and behavior of insects.
But as toxins go, they’re pretty broad-spectrum.
So, researchers think that, to keep from poisoning themselves,
plant cells also produce an enzyme that neutralizes
phenolic glycosides by tacking on a chemical group.
Now, some insects have evolved strategies to thwart these toxins.
Like, some can make enzymes that neutralize a particular plants’ toxin,
allowing them to specialize on that plant.
But whiteflies have long stood out, as they seem to be able
to detoxify any phenolic glycosides they come across.
They’re known to attack at least 600 species of plants worldwide,
and most of those produce a phenolic glycoside as their toxin of choice.
That’s a big part of why they’re such devastating pests!
It’s as if there’s no crop they cannot eat.
So, a Chinese team of researchers decided to take a peek at their
genes in the hopes of finding their toxin-neutralizing secrets.
And as they reported in Cell last week, they discovered
the animals have a plant gene called BtPMaT1.
This gene codes for that toxin-neutralizing enzyme I mentioned before
— the one that probably protects the plants from phenolic glycosides.
And the researchers believe it’s largely responsible for
giving whiteflies their toxin-evading superpowers!
By comparing the different sequences for this gene in whiteflies
and some plants, they estimated that this gene theft probably
happened around 35 million years ago.
However, the scientists behind the paper don’t think the animals acted alone in this theft.
They believe they had a viral accomplice.
Researchers had previously identified a number of genes that viruses
had helped whiteflies pilfer from other organisms, including ones
from bacteria and fungi.
Viruses are just particularly good at snatching genes from their hosts.
And it turns out whiteflies are particularly good
at spreading viruses between plants.
So it’s entirely possible that, while munching away on a plant,
an ancestor of the whitefly ingested a virus containing the stolen gene.
That virus then transferred the plant gene over while it
replicated inside the insect’s cells.
And it was so useful that it stuck around for millions of years.
And so whiteflies are the only insects — that we know of —
that have a functional plant gene.
Of course, there are lots of insects we haven’t looked at genetically
— and lots of plants, for that matter.
So, it’s possible there are other undiscovered cases.
And it may be worth our while to look for them, because
they might help us reduce pesticide use globally!
The researchers behind this study have already developed
a strategy to neutralize the whitefly’s stolen superpower.
They created a small RNA molecule that interferes with the flies’
ability to use the BtPMaT1 gene.
And when they genetically modified tomato plants to produce this small
RNA molecule, all of the whiteflies that tried to eat the plants died.
But, amazingly enough, there was no impact on the survival
of any other tomato-eating insect they tested.
That suggests we could create crops that resist specific pests
without using a drop of pesticide.
Now, there are some hurdles to overcome before this kind of
strategy could go mainstream, of course, like the general
skepticism of genetically modified crops.
Still, this finding could open doors to more environmentally-friendly
strategies for controlling pests.
Not to mention it’s just an incredibly cool discovery!
I mean, an insect adopting a plant defense strategy
so it can eat the plants!
Evolution never ceases to amaze.
Also - an insect has a plant gene!
Do I have a plant gene?!
I don’t know - has anyone checked?!
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