I believe that the secret to producing extremely drought tolerant crops,
which should go some way to providing food security in the world,
lies in Resurrection plants,
pictured here, in an extremely droughted state.
Now you might think that these plants look dead,
but they're not.
Give them water,
and they will resurrect, green up, start growing,
in 12 to 48 hours.
No why would I suggest
that producing drought tolerant crops will go towards providing food security?
Well the current world population is around 7 billion.
And it's estimated that by 2050,
we'll be between 9 and 10 billion people,
with the bulk of this growth happening in Africa.
The food and agricultural organizations of the world
have suggested that we need a 70 percent increase in current agricultural practice
to meet that demand.
Now given that plants are at the base of the food chain,
most of that's going to have to come from plants.
Now that percentage of 70 percent
does not take into consideration the potential effects of climate change.
This is taken from a study by Dye published in 2011,
where he took into consideration
all the potential effects of climate change
and expressed them amongst other things,
increased aridity due to lack or rain or infrequent rain.
Now the areas in red shown here,
are areas that until recently, have been very successfully used for agriculture,
but cannot anymore because of lack of rain fall.
This is the situation that's predicted to happen in 2050.
Much of Africa,
in fact much of the world,
is going to be in trouble.
We're going to have to think of some very smart ways of producing food.
And preferably among them, some drought-tolerant crops.
The other thing to remember about Africa
is that most of the agriculture is rain fed.
Now making drought-tolerant crops is not the easiest thing in the world.
And the reason for this is water.
Water is essential to life on this planet.
All living, actively metabolizing organisms,
from microbes to you and I,
are comprised predominately of water,
all life reactions happen in water,
and loss of a small amount of water results in death.
You and I are 65 percent water,
we lose one percent of that, we die.
But we can make behavioral changes to avoid that.
Plants can't.
They're stuck in the ground.
So in the first instance, they have a little bit more water than us,
about 95 percent water,
and they can lose a little bit more than us,
like 10 to about 70 percent, depending on the species,
but for short periods only.
Most of them will either try to resist or avoid water loss.
So extreme examples of resistors can be found in succulents,
they tend to be small, ver attractive,
but they hold onto their water at such great cost
that they grow extremely slowly.
Examples of avoidance of water loss are found in trees and shrubs.
They send down very deep roots,
mine subterranean water supplies,
and just keep flushing it through them at all times,
keeping themselves hydrated.
The one on the right is called a Baobab,
it's also called the upside-down tree,
simply because the proportion of roots to chutes is so great
that it looks like the tree is being planted upside down.
And of course the roots are required for hydration of that plant.
And probably the most common strategy of avoidance is found in annuals.
Annuals make up the bulk of our plant food supplies.
Up the west coast of my country,
for much the year you don't see much vegetation growth.
But come the spring rains,
you get this.
Flowering of the desert.
Now the strategy in annuals,
is to grow only in the rainy season.
At the end of that season they produce a seed,
which is dry, eight to 10 percent water,
but very much alive.
And anything that is that dry and still alive,
we call desiccation-tolerant.
The next time the rainy season comes,
they germinate and grow,
and the whole cycle just starts again.
It's widely believed that the evolution of desiccation-tolerant seeds
allowed the colonization and the radiation of flowering plants, or angiosperms,
onto land.
But back to annuals as our major form of food supplies.
Wheat, rice and maze form 95 percent of our plant food supplies.
And it's been a great strategy,
because in a short space of time you can produce a lot of seed,
seeds are energy-rich so you can store a lot of food calories,
you can store it in times of plenty for times of famine,
but there's a down side.
The vegetative tissues,
the roots and leaves of annuals,
do not have much by way
of inherent resistance, avoidance or tolerance characteristics.
They just don't need them.
They grow in the rainy season
and they've got a seed to help them survive the rest of the year.
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.
Maze crop in Africa,
two weeks without rain,
and it's dead.
Now 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, they 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.
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.
[Video]
(Applause)
Pretty amazing, huh?
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.
One of them being is that each of these plants serve as a model
for a crop that I'd like to make drought-tolerant.
So on the extreme top left for example,
is a grass, it's called Eragrostis Nindensis,
it's called a close relative called Eragrostis Tef,
a lot of you might know it as "Tef,"
it's a staple food in Ethiopia,
it's gluten-free,
and it's something we would like to make drought-tolerant.
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?
So I undertook what we call a Systems Biology approach.