And so despite concerted efforts in agriculture to make crops with improved properties of resistance, avoidance and tolerance -- particularly resistance and avoidance because we've had good models to understand how those work -- we still get images like this. Maize crop in Africa, two weeks without rain and it's dead.
05:36
There is a solution: resurrection plants. These plants can lose 95 percent of their cellular water, remain in a dry, dead-like state for months to years, and give them water, they green up and start growing again. Like seeds, these are desiccation-tolerant. Like seeds, these can withstand extremes of environmental conditions. And this is a really rare phenomenon. There are only 135 flowering plant species that can do this.
06:07
I'm going to show you a video of the resurrection process of these three species in that order. And at the bottom, there's a time axis so you can see how quickly it happens.
06:55
(Applause)
07:01
Pretty amazing, huh?
07:02
So I've spent the last 21 years trying to understand how they do this. How do these plants dry without dying? And I work on a variety of different resurrection plants, shown here in the hydrated and dry states, for a number of reasons.
07:16
One of them is that each of these plants serves as a model for a crop that I'd like to make drought-tolerant.
07:22
So on the extreme top left, for example, is a grass, it's called Eragrostis nindensis, it's got a close relative called Eragrostis tef -- a lot of you might know it as "teff" -- it's a staple food in Ethiopia, it's gluten-free, and it's something we would like to make drought-tolerant.
07:37
The other reason for looking at a number of plants, is that, as least initially, I wanted to find out: do they do the same thing? Do they all use the same mechanisms to be able to lose all that water and not die?
07:48
So I undertook what we call a systems biology approach in order to get a comprehensive understanding of desiccation tolerance, in which we look at everything from the molecular to the whole plant, ecophysiological level.
07:59
For example we look at things like changes in the plant anatomy as they dried out and their ultrastructure. We look at the transcriptome, which is just a term for a technology in which we look at the genes that are switched on or off, in response to drying. Most genes will code for proteins, so we look at the proteome. What are the proteins made in response to drying? Some proteins would code for enzymes which make metabolites, so we look at the metabolome.
08:24
Now, this is important because plants are stuck in the ground. They use what I call a highly tuned chemical arsenal to protect themselves from all the stresses of their environment. So it's important that we look at the chemical changes involved in drying.
08:39
And at the last study that we do at the molecular level, we look at the lipidome -- the lipid changes in response to drying. And that's also important because all biological membranes are made of lipids. They're held as membranes because they're in water. Take away the water, those membranes fall apart. Lipids also act as signals to turn on genes.
08:59
Then we use physiological and biochemical studies to try and understand the function of the putative protectants that we've actually discovered in our other studies. And then use all of that to try and understand how the plant copes with its natural environment.
09:14
I've always had the philosophy that I needed a comprehensive understanding of the mechanisms of desiccation tolerance in order to make a meaningful suggestion for a biotic application.
09:26
I'm sure some of you are thinking, "By biotic application, does she mean she's going to make genetically modified crops?" And the answer to that question is: depends on your definition of genetic modification.