0:00:01.000,0:00:05.178
I believe that the secret to producing[br]extremely drought tolerant crops,

0:00:05.178,0:00:08.460
which should go some way[br]to providing food security in the world,

0:00:08.460,0:00:11.202
lies in resurrection plants,

0:00:11.202,0:00:14.372
pictured here, in an extremely[br]droughted state.

0:00:14.372,0:00:17.196
Now you might think[br]that these plants look dead,

0:00:17.196,0:00:18.589
but they're not.

0:00:18.589,0:00:20.013
Give them water,

0:00:20.013,0:00:25.331
and they will resurrect, green up,[br]start growing, in 12 to 48 hours.

0:00:26.624,0:00:28.160
Now why would I suggest

0:00:28.160,0:00:32.456
that producing drought tolerant crops[br]will go towards providing food security?

0:00:33.334,0:00:37.024
Well the current world population[br]is around 7 billion.

0:00:37.024,0:00:39.617
And it's estimated that by 2050,

0:00:39.617,0:00:42.368
we'll be between 9 and 10 billion people,

0:00:42.368,0:00:45.803
with the bulk of this growth[br]happening in Africa.

0:00:46.091,0:00:48.544
The food and agricultural[br]organizations of the world

0:00:48.544,0:00:51.713
have suggested that we need[br]a 70 percent increase

0:00:51.713,0:00:54.022
in current agricultural practice

0:00:54.022,0:00:55.921
to meet that demand.

0:00:55.921,0:00:58.555
Now given that plants[br]are at the base of the food chain,

0:00:58.555,0:01:01.024
most of that's going[br]to have to come from plants.

0:01:01.718,0:01:04.342
Now that percentage of 70 percent

0:01:04.342,0:01:08.233
does not take into consideration[br]the potential effects of climate change.

0:01:08.637,0:01:13.339
This is taken from a study by Dye[br]published in 2011,

0:01:13.339,0:01:15.424
where he took into consideration[br]

0:01:15.424,0:01:17.600
all the potential effects[br]of climate change

0:01:17.600,0:01:18.600
and expressed them --

0:01:18.600,0:01:19.820
amongst other things --

0:01:19.820,0:01:24.508
increased aridity due to lack of rain[br]or infrequent rain.

0:01:24.508,0:01:26.423
Now the areas in red shown here,

0:01:26.423,0:01:28.494
are areas that until recently,

0:01:28.494,0:01:31.494
have been very successfully[br]used for agriculture,

0:01:31.494,0:01:34.805
but cannot anymore[br]because of lack of rain fall.

0:01:34.805,0:01:38.699
This is the situation[br]that's predicted to happen in 2050.

0:01:38.937,0:01:40.099
Much of Africa,

0:01:40.099,0:01:41.393
in fact much of the world,

0:01:41.393,0:01:43.162
is going to be in trouble.

0:01:43.162,0:01:46.746
We're going to have to think of some[br]very smart ways of producing food.

0:01:46.746,0:01:50.297
And preferably among them,[br]some drought-tolerant crops.

0:01:50.297,0:01:52.237
The other thing to remember about Africa

0:01:52.237,0:01:55.348
is that most of the[br]agriculture is rainfed.

0:01:56.242,0:01:59.637
Now making drought-tolerant crops[br]is not the easiest thing in the world.

0:01:59.637,0:02:02.256
And the reason for this is water.

0:02:02.256,0:02:05.326
Water is essential to life on this planet.

0:02:05.435,0:02:09.498
All living, actively[br]metabolizing organisms,

0:02:09.498,0:02:11.555
from microbes to you and I,

0:02:11.555,0:02:13.939
are comprised predominately of water,[br]

0:02:13.939,0:02:16.432
all life reactions happen in water,

0:02:16.432,0:02:19.650
and loss of a small amount[br]of water results in death.

0:02:19.650,0:02:21.758
You and I are 65 percent water,

0:02:21.758,0:02:23.952
we lose one percent of that, we die.

0:02:23.952,0:02:27.465
But we can make behavioral[br]changes to avoid that.

0:02:28.166,0:02:29.792
Plants can't.

0:02:29.792,0:02:31.394
They're stuck in the ground.

0:02:31.394,0:02:34.738
And so in the first instance they have[br]a little bit more water than us,

0:02:34.738,0:02:36.092
about 95 percent water,

0:02:36.092,0:02:38.162
and they can lose[br]a little bit more than us,

0:02:38.162,0:02:42.230
like 10 to about 70 percent,[br]depending on the species,

0:02:42.230,0:02:44.413
but for short periods only.

0:02:44.880,0:02:49.088
Most of them will either try to resist[br]or avoid water loss.

0:02:49.088,0:02:52.921
So extreme examples of resistors[br]can be found in succulents,

0:02:52.921,0:02:55.970
they tend to be small, very attractive,

0:02:55.970,0:02:58.748
but they hold onto their water[br]at such great cost

0:02:58.748,0:03:01.442
that they grow extremely slowly.

0:03:01.727,0:03:05.535
Examples of avoidance of water loss[br]are found in trees and shrubs.

0:03:06.205,0:03:07.917
They send down very deep roots,

0:03:07.917,0:03:09.529
mine subterranean water supplies,

0:03:09.529,0:03:11.986
and just keep flushing[br]it through them at all times,

0:03:11.986,0:03:13.966
keeping themselves hydrated.

0:03:13.966,0:03:16.032
The one on the right is called a Baobab,

0:03:16.032,0:03:18.047
it's also called the upside-down tree,

0:03:18.047,0:03:21.713
simply because the proportion[br]of roots to chutes is so great

0:03:21.713,0:03:24.430
that it looks like the tree[br]is being planted upside down.

0:03:24.430,0:03:27.542
And of course the roots are required[br]for hydration of that plant.

0:03:29.434,0:03:34.217
And probably the most common strategy[br]of avoidance is found in annuals.

0:03:34.217,0:03:36.980
Annuals make up the bulk[br]of our plant food supplies.

0:03:37.275,0:03:39.000
Up the west coast of my country,

0:03:39.000,0:03:42.399
for much the year you don't see[br]much vegetation growth.

0:03:42.399,0:03:43.916
But come the spring rains,

0:03:43.916,0:03:45.284
you get this.

0:03:45.284,0:03:47.293
Flowering of the desert.

0:03:47.293,0:03:49.072
Now the strategy in annuals,

0:03:49.072,0:03:51.441
is to grow only in the rainy season.

0:03:52.158,0:03:54.489
At the end of that season[br]they produce a seed,

0:03:54.489,0:03:57.182
which is dry, eight to 10 percent water,

0:03:57.182,0:03:59.022
but very much alive.

0:03:59.022,0:04:02.009
And anything that is[br]that dry and still alive,

0:04:02.009,0:04:04.159
we call desiccation-tolerant.

0:04:04.159,0:04:05.519
Now in the desiccated state,

0:04:05.519,0:04:08.009
what seeds can do[br]is lie in extremes of environment

0:04:08.009,0:04:09.565
for prolonged periods of time.

0:04:09.565,0:04:12.038
The next time the rainy season comes,

0:04:12.038,0:04:13.942
they germinate and grow,

0:04:13.942,0:04:16.148
and the whole cycle just starts again.

0:04:16.435,0:04:20.303
It's widely believed that the evolution[br]of desiccation-tolerant seeds

0:04:20.303,0:04:22.792
allowed the colonization and the radiation

0:04:22.792,0:04:26.872
of flowering plants, [br]or angiosperms, onto land.

0:04:27.243,0:04:30.749
But back to annuals[br]as our major form of food supplies.

0:04:31.121,0:04:35.811
Wheat, rice and maze form 95 percent[br]of our plant food supplies.

0:04:36.670,0:04:38.342
And it's been a great strategy,

0:04:38.342,0:04:41.483
because in a short space of time[br]you can produce a lot of seed.

0:04:41.483,0:04:44.130
Seeds are energy-rich so there's[br]a lot of food calories,

0:04:44.130,0:04:48.677
you can store it in times of plenty[br]for times of famine,

0:04:48.677,0:04:50.757
but there's a down side.

0:04:50.757,0:04:52.267
The vegetative tissues --

0:04:52.267,0:04:54.408
the roots and leaves of annuals --

0:04:54.408,0:04:55.496
do not have much

0:04:55.496,0:04:59.774
by way of inherent resistance,[br]avoidance or tolerance characteristics.

0:04:59.774,0:05:01.056
They just don't need them.

0:05:01.056,0:05:02.455
They grow in the rainy season

0:05:02.455,0:05:05.845
and they've got a seed to help them[br]survive the rest of the year.

0:05:05.845,0:05:08.652
And so despite concerted[br]efforts in agriculture

0:05:08.652,0:05:11.400
to make crops with improved properties

0:05:11.400,0:05:13.517
of resistance, avoidance and tolerance --

0:05:13.517,0:05:15.321
particularly resistance and avoidance

0:05:15.321,0:05:18.201
because we've had good models[br]to understand how those work --

0:05:18.201,0:05:20.591
we still get images like this.

0:05:20.591,0:05:22.091
Maze crop in Africa,

0:05:22.091,0:05:23.604
two weeks without rain,

0:05:23.604,0:05:25.485
and it's dead.

0:05:25.805,0:05:27.677
Now there is a solution.

0:05:27.677,0:05:29.482
Resurrection plants.

0:05:29.715,0:05:33.267
These plants can lose 95 percent[br]of their cellular water,

0:05:33.267,0:05:37.192
remain in a dry, dead-like state[br]for months to years,

0:05:37.192,0:05:39.121
and give them water,

0:05:39.121,0:05:41.892
they green up and start growing again.

0:05:41.892,0:05:45.061
Like seeds, these are desiccation-tolerant.

0:05:45.061,0:05:49.472
Like seeds, these can withstand extremes[br]of environmental conditions.

0:05:50.003,0:05:52.136
And this is a really rare phenomenon.

0:05:52.136,0:05:56.157
There are only 135 flowering[br]plant species that can do this.

0:05:56.424,0:05:57.807
I'm going to show you a video

0:05:57.807,0:06:00.416
of the resurrection process[br]of these three species

0:06:00.416,0:06:01.809
in that order.

0:06:01.809,0:06:02.858
And at the bottom,

0:06:02.858,0:06:05.658
there's a time axis so you can see[br]how quickly it happens.

0:06:05.658,0:06:06.668
[Video]

0:06:44.661,0:06:46.844
(Applause)

0:06:50.489,0:06:51.975
Pretty amazing, huh?

0:06:51.975,0:06:56.189
So I've spent the last 21 years[br]trying to understand how they do this.

0:06:56.189,0:06:59.351
How do these plants dry without dying?

0:06:59.351,0:07:02.072
And I work on a variety of different[br]resurrection plants,

0:07:02.072,0:07:04.581
shown here in the hydrated and dry states,

0:07:04.581,0:07:06.229
for a number of reasons.

0:07:06.229,0:07:09.206
One of them being is that[br]each of these plants serve as a model

0:07:09.206,0:07:11.590
for a crop that I'd like[br]to make drought-tolerant.

0:07:11.590,0:07:13.360
So on the extreme top left for example,

0:07:13.360,0:07:16.461
is a grass, it's called[br]Eragrostis Nindensis,

0:07:16.461,0:07:18.890
it's got a close relative[br]called Eragrostis Tef --

0:07:18.890,0:07:20.975
a lot of you might know it as "Tef" --

0:07:20.975,0:07:22.787
it's a staple food in Ethiopia,

0:07:22.787,0:07:24.042
it's gluten-free,

0:07:24.042,0:07:26.989
and it's something we would like[br]to make drought-tolerant.

0:07:27.151,0:07:28.986
The other reason for looking[br]at a number of plants,

0:07:29.195,0:07:30.681
is that, as least initially,

0:07:30.843,0:07:32.654
I wanted to find out:[br]do they do the same thing?

0:07:33.049,0:07:34.512
Do they all use the same mechanisms

0:07:34.674,0:07:36.973
to be able to lose[br]all that water and not die?

0:07:37.530,0:07:40.270
So I undertook what we call[br]a Systems Biology approach

0:07:40.456,0:07:42.383
in order to get[br]a comprehensive understanding

0:07:42.569,0:07:44.171
of desiccation tolerance,

0:07:44.589,0:07:46.237
in which we look at everything

0:07:46.493,0:07:48.884
from the molecular to the whole plant[br]ecophysiological level.

0:07:49.325,0:07:50.904
For example we look at things like

0:07:51.113,0:07:52.390
changes in the plant anatomy[br]when they're dried out,

0:07:52.576,0:07:53.853
and their ultrasctructure.

0:07:54.085,0:07:55.293
We look at the transcriptome,

0:07:55.595,0:07:56.941
which is just a term for a technology

0:07:57.150,0:07:58.590
in which we look at the genes[br]that are switched on or off,

0:07:58.892,0:08:00.958
in response to drying.

0:08:01.260,0:08:04.371
Most genes will code for proteins[br]so we look at the proteome.

0:08:04.650,0:08:07.367
What are the proteins made[br]in response to drying?

0:08:07.831,0:08:11.616
Some proteins would code for enzymes[br]which make metabolytes,

0:08:11.801,0:08:13.496
so we look at the metabolome.

0:08:13.729,0:08:16.585
Now this is important because plants[br]are stuck in the ground.

0:08:16.747,0:08:20.717
They use what I call a highly tuned[br]chemical arsenal

0:08:20.926,0:08:23.945
to protect themselves from all[br]the stresses of their environment.

0:08:24.224,0:08:25.593
So it's important that we look[br]

0:08:25.802,0:08:28.357
at the chemical changes[br]involved in drying.

0:08:28.844,0:08:31.630
The last study that we do[br]at the molecular level

0:08:31.793,0:08:32.815
is we study the lipidome --

0:08:33.047,0:08:34.858
the lipid changes in response to drying.

0:08:35.136,0:08:36.158
And that's also important

0:08:36.367,0:08:38.968
because all biological membranes[br]are made of lipids.

0:08:39.200,0:08:41.406
They're held as membranes[br]because they're in water.

0:08:41.684,0:08:44.262
Take away the water,[br]those membranes fall apart.

0:08:44.656,0:08:48.046
Lipids also act as signals[br]to turn on genes.

0:08:48.511,0:08:51.042
Then we use physiological[br]and biochemical studies

0:08:51.250,0:08:52.783
to try and understand the function

0:08:52.992,0:08:56.962
of the putative protectants that we've[br]actually discovered in our other studies.

0:08:57.427,0:08:59.261
And we use all of that[br]to try and understand

0:08:59.470,0:09:02.117
how the plant copes[br]with its natural environment.

0:09:03.742,0:09:05.530
Now I've always had the philosphy

0:09:05.762,0:09:07.875
that I needed a comprehensive[br]understanding

0:09:08.177,0:09:09.942
of the mechanisms of desiccation tolerance

0:09:10.313,0:09:14.353
in order to make a meaningful suggestion[br]for a biotic application.

0:09:15.329,0:09:16.722
I'm sure some of you are thinking,

0:09:16.931,0:09:21.226
"by biotic application, so she mean she's[br]going to make genetically modified crops?"

0:09:22.573,0:09:23.804
And the answer to that question is,

0:09:24.129,0:09:27.519
it depends on your definition[br]of genetic modification.

0:09:27.797,0:09:30.444
All of the crops that we eat today,[br]wheat, grass and maze,

0:09:30.676,0:09:33.138
are highly genetically modified[br]from their ancenstors,

0:09:33.463,0:09:35.227
but we don't consider them "GM"

0:09:35.576,0:09:38.478
because they're being produced[br]by conventional breeding.

0:09:39.174,0:09:39.941
If you mean,

0:09:40.126,0:09:42.147
"am I going to put resurrection plant[br]genes into crops?"

0:09:42.448,0:09:44.190
your answer is yes.

0:09:44.399,0:09:47.185
In the essence of time,[br]we have tried that approach.

0:09:47.510,0:09:48.648
More appropriately,

0:09:48.973,0:09:50.320
some of my collaborators at UCT,

0:09:50.529,0:09:51.875
Jennifer Thomson and Suhail Rafudeeen,

0:09:52.247,0:09:53.686
have spearheaded that approach

0:09:53.942,0:09:56.055
and I'm going to show you[br]some data soon.

0:09:57.471,0:10:01.209
But we're about to embark upon[br]an extremely ambitious approach,

0:10:01.465,0:10:04.367
in which we aim to turn on[br]whole suites of genes

0:10:04.692,0:10:07.362
that are already present in every crop.

9:59:59.000,9:59:59.000
They're just never turned on[br]under extreme drought conditions.

9:59:59.000,9:59:59.000
I leave it up to you to decide

9:59:59.000,9:59:59.000
whether those should[br]be called "GM" or not.

9:59:59.000,9:59:59.000
I'm going to now just give you[br]some of the data from that first approach.

9:59:59.000,9:59:59.000
And in order to do that

9:59:59.000,9:59:59.000
I have to explain a little bit[br]about how genes work.

9:59:59.000,9:59:59.000
So you probably all know

9:59:59.000,9:59:59.000
that genes are made[br]of double-stranded DNA.

9:59:59.000,9:59:59.000
It's wound very tightly into chromosomes

9:59:59.000,9:59:59.000
that are present[br]in every cell of your body,

9:59:59.000,9:59:59.000
or in a plant's body.

9:59:59.000,9:59:59.000
If you unwind that DNA, you get genes.

9:59:59.000,9:59:59.000
And each gene has a promoter,

9:59:59.000,9:59:59.000
which is an on/off switch,

9:59:59.000,9:59:59.000
the gene coding region,

9:59:59.000,9:59:59.000
and then the terminator,

9:59:59.000,9:59:59.000
which indicates

9:59:59.000,9:59:59.000
that this is the end of this gene,[br]the next gene will start.

9:59:59.000,9:59:59.000
Now promoters are not[br]simple on-off switches.

9:59:59.000,9:59:59.000
They normally require[br]a lot of fine tuning,

9:59:59.000,9:59:59.000
lots of things to be present and correct[br]before that gene is switched on.

9:59:59.000,9:59:59.000
So what's typically done[br]in biotech studies

9:59:59.000,9:59:59.000
is that we use an inducible promoter,

9:59:59.000,9:59:59.000
we know how to switch it on.

9:59:59.000,9:59:59.000
We couple that to genes of interest,

9:59:59.000,9:59:59.000
and put that into a plant

9:59:59.000,9:59:59.000
and see how the plant responds.

9:59:59.000,9:59:59.000
Now in the study that I'm going[br]to talk to you about,

9:59:59.000,9:59:59.000
my collaborators used[br]a drought-induced promoter,

9:59:59.000,9:59:59.000
which we discovered[br]in a resurrection plant.

9:59:59.000,9:59:59.000
Now the nice thing about this promoter[br]is that we do nothing.

9:59:59.000,9:59:59.000
The plant itself senses drought.

9:59:59.000,9:59:59.000
And we've used it

9:59:59.000,9:59:59.000
to drive antioxidant genes[br]from resurrection plants.

9:59:59.000,9:59:59.000
Why antioxidant genes?

9:59:59.000,9:59:59.000
Well, all stresses,[br]particularly drought stress,

9:59:59.000,9:59:59.000
results in the formation of free radicals,

9:59:59.000,9:59:59.000
or reactive oxygen species,

9:59:59.000,9:59:59.000
which are highly damaging[br]and can cause crop death.

9:59:59.000,9:59:59.000
What antioxidants do is stop that damage.

9:59:59.000,9:59:59.000
So here's some data from a main strain[br]that's very popularly used in Africa.

9:59:59.000,9:59:59.000
To the left of the arrow are plants[br]without the genes,

9:59:59.000,9:59:59.000
to the right --

9:59:59.000,9:59:59.000
plants with the antioxidant genes.

9:59:59.000,9:59:59.000
After three weeks without watering,

9:59:59.000,9:59:59.000
the ones with the genes[br]do a hell of a lot better.

9:59:59.000,9:59:59.000
Now to the final approach.

9:59:59.000,9:59:59.000
My research has shown

9:59:59.000,9:59:59.000
that there's considerable similarity[br]in the mechanisms of desiccation tolerance

9:59:59.000,9:59:59.000
in seeds and resurrection plants.

9:59:59.000,9:59:59.000
So I ask the question,

9:59:59.000,9:59:59.000
are they using the same genes?

9:59:59.000,9:59:59.000
Or slightly differently phrased,

9:59:59.000,9:59:59.000
are resurrection plants utilizing genes[br]evolved for seed desiccation tolerance

9:59:59.000,9:59:59.000
in their roots and leaves?

9:59:59.000,9:59:59.000
Have they re-tasked these seed genes

9:59:59.000,9:59:59.000
in roots and leaves[br]of resurrection plants?

9:59:59.000,9:59:59.000
And I answer that question,

9:59:59.000,9:59:59.000
as a consequence of a lot[br]of research from my group

9:59:59.000,9:59:59.000
and recent collaborations from a group[br]of Henk Hilhorst in the Netherlands,

9:59:59.000,9:59:59.000
Mel Oliver in the United States,

9:59:59.000,9:59:59.000
and Julia Buitink, in France,

9:59:59.000,9:59:59.000
the answer is, yes.

9:59:59.000,9:59:59.000
There is a core set of genes[br]that are involved in both.

9:59:59.000,9:59:59.000
And I'm going to illustrate this[br]very crudely for maze,

9:59:59.000,9:59:59.000
where the chromosomes[br]below the off switch

9:59:59.000,9:59:59.000
represent all the genes that are required[br]for desiccation tolerance.

9:59:59.000,9:59:59.000
So as maze seeds dried on[br]at the end of their period of development,

9:59:59.000,9:59:59.000
they switch these genes on.

9:59:59.000,9:59:59.000
Resurrection plants[br]switch on the same genes

9:59:59.000,9:59:59.000
when they're dried on.

9:59:59.000,9:59:59.000
All modern crops, therefore,

9:59:59.000,9:59:59.000
have these genes[br]in their roots and leaves,

9:59:59.000,9:59:59.000
they just never switch them on.

9:59:59.000,9:59:59.000
They only switch them on in seed tissues.

9:59:59.000,9:59:59.000
So what we're trying to do right now

9:59:59.000,9:59:59.000
is to understand the environmental[br]and cellular signals

9:59:59.000,9:59:59.000
which switch on these genes[br]in resurrection plants,

9:59:59.000,9:59:59.000
to mimic the process in crops.

9:59:59.000,9:59:59.000
And just a final thought.

9:59:59.000,9:59:59.000
What we're trying to do very rapidly,

9:59:59.000,9:59:59.000
is to repeat what nature did[br]in the evolution of resurrection plants

9:59:59.000,9:59:59.000
some 10 to 40 million years ago.

9:59:59.000,9:59:59.000
My plants and I[br]thank you for your attention.

9:59:59.000,9:59:59.000
(Applause)