How we can make crops survive without water

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.