Plants are weird!
Maybe I should be a bit more specific...
Plants have weird immune systems.
Scientists know a lot about how to plant immune system works, but
there's still a lot that we don't know! Researchers at Duke University have
learned a little bit more about how the plant immune system works, and
what they've learned can help us make a better disease resistant plant that could lower pesticide use!
We're going to cover a lot of information right now because
these researchers published their findings in not one, but two papers
back-to-back in the same journal!
The first paper was on a new aspect of the plant immune system, and
the second paper looked at how that aspect can be used to
create a better disease resistant plant.
So why do we want disease resistant plants?
Well obviously we want our plants to be healthy and delicious, but
disease resistant plants come with an added benefit.
If plants are better able to defend themselves, they won't need the help of things like pesticides.
The problem is that disease resistant plants are difficult to get.
Plants have two states of being: defense mode and growth mode.
But they can only be in one of those states at a time.
So you can either have a plant that's really good at defending itself but it's kind of shrimpy...
Or you can have a really big plant that's prone to infection.
What we really need are some cheat codes that will
give us a really big plant that's also good at defending itself, and
these researchers may have just found that cheat code.
In order to get how their discovery enables that cheat code, we
need to understand how the plant immune system works.
Compared to humans and other animals, plants have a really weird immune system.
Humans have innate and adaptive immunity.
Our innate immune system has general defense against pathogens, and
our adaptive immune system focuses on taking down individual pathogens like the flu or chickenpox.
The adaptive immune system is what works when you get a vaccine.
Plants don't have an adaptive immune system.
They only have an innate one, but even their innate immune system is a little weird.
They don't have immune cells!
Instead of having specific cells that just do immune work...
all plant cells have immune capabilities!
They all have proteins on their surface that recognize different molecules from
a variety of pathogens. Once they recognize those molecules...
they sound the alarm and start a cascade of events that puts the plant into defense mode.
The ultimate goal of defense mode is to get proteins that will help defend
the plant against the invading pathogen, but there are a couple of ways to get
more defensive proteins. To get a defensive protein you have a defensive protein gene that
then gets copied and then that copy gets read into protein.
So, if you want more protein you can either increase the number of copies you make...
or increase the speed or the number of times that you read that copy.
Because there are two controlling steps in this process, the number of copies that you
have doesn't guarantee how much protein you're going to have.
Just like the number of books you own doesn't mean that you're well read.
you could own 50 books but I've only really read one of them.
Scientists knew that when plants recognize that they have a pathogen, they change
the number of defensive protein gene copies they have, but we were missing part of the story.
These researchers looked specifically at how plant cells read these copies when
switching from growth mode to defense mode.
They found out that the copies of defensive protein genes have a special signal on them that
tells the cell to only read that copy when the pathogen is around.
The researchers try putting the special signal on copies of genes that provide a broad protective effect for
the plant. Usually this kind of broad protective protein takes up a lot of the
plant's energy and makes it really small, but safe.
By putting this special signal on the broad protective protein, you get a plant that's really
quick to respond to infections without actually being in defense mode!
It's kind of like having a neighborhood watch instead of a full police force.
The full police force takes a lot of time and resources, but a neighborhood watch could
be just as effective at dealing with trouble without all of the costly resources.
This work was done in a small flowering weed called Arabidopsis and
also in rice, but future work is going to have to see if the special signal works
well in other plants too.
Maybe this new understanding of plant immune systems can
help keep our plants happy, healthy, and pesticide free for the days to come.
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See you next time!
It's a pretty good book