TEDGlobal>Geneva
Jill Farrant: How we can make crops survive without water
Filmed:
Readability: 4.6
1,562,697 views
As the world's population grows and the effects of climate change come into sharper relief, we'll have to feed more people using less arable land. Molecular biologist Jill Farrant studies a rare phenomenon that may help: "resurrection plants" -- super-resilient plants that seemingly come back from the dead. Could they hold promise for growing food in our coming hotter, drier world?
Jill Farrant - Professor of molecular and cell biology
Jill Farrant is leading the development of drought-tolerant crops to nourish populations in arid climates. Full bio
Jill Farrant is leading the development of drought-tolerant crops to nourish populations in arid climates. Full bio
Double-click the English transcript below to play the video.
00:12
I believe that the secret to producing
extremely drought-tolerant crops,
extremely drought-tolerant crops,
0
840
4216
00:17
which should go some way
to providing food security in the world,
to providing food security in the world,
1
5080
3216
00:20
lies in resurrection plants,
2
8320
2696
00:23
pictured here, in an extremely
droughted state.
droughted state.
3
11040
3136
00:26
You might think
that these plants look dead,
that these plants look dead,
4
14200
2856
00:29
but they're not.
5
17080
1296
00:30
Give them water,
6
18400
1456
00:31
and they will resurrect, green up,
start growing, in 12 to 48 hours.
start growing, in 12 to 48 hours.
7
19880
5440
00:38
Now, why would I suggest
8
26320
1296
00:39
that producing drought-tolerant crops
will go towards providing food security?
will go towards providing food security?
9
27640
4440
00:45
Well, the current world population
is around 7 billion.
is around 7 billion.
10
33040
3896
00:48
And it's estimated that by 2050,
11
36960
2496
00:51
we'll be between 9 and 10 billion people,
12
39480
2696
00:54
with the bulk of this growth
happening in Africa.
happening in Africa.
13
42200
2880
00:57
The food and agricultural
organizations of the world
organizations of the world
14
45880
2456
01:00
have suggested that we need
a 70 percent increase
a 70 percent increase
15
48360
3136
01:03
in current agricultural practice
16
51520
2176
01:05
to meet that demand.
17
53720
1240
01:07
Given that plants
are at the base of the food chain,
are at the base of the food chain,
18
55720
2696
01:10
most of that's going
to have to come from plants.
to have to come from plants.
19
58440
2320
01:13
That percentage of 70 percent
20
61360
2696
01:16
does not take into consideration
the potential effects of climate change.
the potential effects of climate change.
21
64080
4216
01:20
This is taken from a study by Dai
published in 2011,
published in 2011,
22
68320
4240
01:25
where he took into consideration
23
73240
1936
01:27
all the potential effects
of climate change
of climate change
24
75200
2376
01:29
and expressed them --
amongst other things --
amongst other things --
25
77600
2136
01:31
increased aridity due to lack of rain
or infrequent rain.
or infrequent rain.
26
79760
4616
01:36
The areas in red shown here,
27
84400
1776
01:38
are areas that until recently
28
86200
2056
01:40
have been very successfully
used for agriculture,
used for agriculture,
29
88280
3176
01:43
but cannot anymore
because of lack of rainfall.
because of lack of rainfall.
30
91480
2400
01:46
This is the situation
that's predicted to happen in 2050.
that's predicted to happen in 2050.
31
94640
2920
01:50
Much of Africa,
in fact, much of the world,
in fact, much of the world,
32
98840
2176
01:53
is going to be in trouble.
33
101040
1896
01:54
We're going to have to think of some
very smart ways of producing food.
very smart ways of producing food.
34
102960
3656
01:58
And preferably among them,
some drought-tolerant crops.
some drought-tolerant crops.
35
106640
3296
02:01
The other thing
to remember about Africa is
to remember about Africa is
36
109960
2056
02:04
that most of their agriculture is rainfed.
37
112040
2800
02:08
Now, making drought-tolerant crops
is not the easiest thing in the world.
is not the easiest thing in the world.
38
116080
3456
02:11
And the reason for this is water.
39
119560
2416
02:14
Water is essential to life on this planet.
40
122000
3136
02:17
All living, actively
metabolizing organisms,
metabolizing organisms,
41
125160
4135
02:21
from microbes to you and I,
42
129320
2056
02:23
are comprised predominately of water.
43
131400
2336
02:25
All life reactions happen in water.
44
133760
2536
02:28
And loss of a small amount
of water results in death.
of water results in death.
45
136320
3016
02:31
You and I are 65 percent water --
46
139360
2056
02:33
we lose one percent of that, we die.
47
141440
1720
02:35
But we can make behavioral
changes to avoid that.
changes to avoid that.
48
143840
2720
02:39
Plants can't.
49
147920
1576
02:41
They're stuck in the ground.
50
149520
1616
02:43
And so in the first instance they have
a little bit more water than us,
a little bit more water than us,
51
151160
3376
02:46
about 95 percent water,
52
154560
1256
02:47
and they can lose
a little bit more than us,
a little bit more than us,
53
155840
2096
02:49
like 10 to about 70 percent,
depending on the species,
depending on the species,
54
157960
2960
02:54
but for short periods only.
55
162000
1360
02:56
Most of them will either try
to resist or avoid water loss.
to resist or avoid water loss.
56
164680
4176
03:00
So extreme examples of resistors
can be found in succulents.
can be found in succulents.
57
168880
3936
03:04
They tend to be small, very attractive,
58
172840
2816
03:07
but they hold onto their water
at such great cost
at such great cost
59
175680
2736
03:10
that they grow extremely slowly.
60
178440
2000
03:13
Examples of avoidance of water loss
are found in trees and shrubs.
are found in trees and shrubs.
61
181440
4576
03:18
They send down very deep roots,
62
186040
1576
03:19
mine subterranean water supplies
63
187640
1696
03:21
and just keep flushing
it through them at all times,
it through them at all times,
64
189360
2456
03:23
keeping themselves hydrated.
65
191840
1856
03:25
The one on the right is called a baobab.
66
193720
1976
03:27
It's also called the upside-down tree,
67
195720
2056
03:29
simply because the proportion
of roots to shoots is so great
of roots to shoots is so great
68
197800
3776
03:33
that it looks like the tree
has been planted upside down.
has been planted upside down.
69
201600
2696
03:36
And of course the roots are required
for hydration of that plant.
for hydration of that plant.
70
204320
3240
03:40
And probably the most common strategy
of avoidance is found in annuals.
of avoidance is found in annuals.
71
208760
4520
03:45
Annuals make up the bulk
of our plant food supplies.
of our plant food supplies.
72
213840
3176
03:49
Up the west coast of my country,
73
217040
1696
03:50
for much of the year
you don't see much vegetation growth.
you don't see much vegetation growth.
74
218760
3536
03:54
But come the spring rains, you get this:
75
222320
2656
03:57
flowering of the desert.
76
225000
1240
03:59
The strategy in annuals,
77
227000
1856
04:00
is to grow only in the rainy season.
78
228880
2360
04:03
At the end of that season
they produce a seed,
they produce a seed,
79
231960
2296
04:06
which is dry, eight to 10 percent water,
80
234280
2816
04:09
but very much alive.
81
237120
1656
04:10
And anything that is
that dry and still alive,
that dry and still alive,
82
238800
2896
04:13
we call desiccation-tolerant.
83
241720
1480
04:15
In the desiccated state,
84
243840
1416
04:17
what seeds can do
is lie in extremes of environment
is lie in extremes of environment
85
245280
2656
04:19
for prolonged periods of time.
86
247960
1656
04:21
The next time the rainy season comes,
87
249640
2216
04:23
they germinate and grow,
88
251880
1496
04:25
and the whole cycle just starts again.
89
253400
1880
04:28
It's widely believed that the evolution
of desiccation-tolerant seeds
of desiccation-tolerant seeds
90
256120
4056
04:32
allowed the colonization and the radiation
91
260200
2176
04:34
of flowering plants,
or angiosperms, onto land.
or angiosperms, onto land.
92
262400
3520
04:38
But back to annuals
as our major form of food supplies.
as our major form of food supplies.
93
266960
3160
04:42
Wheat, rice and maize form 95 percent
of our plant food supplies.
of our plant food supplies.
94
270800
4720
04:48
And it's been a great strategy
95
276480
1536
04:50
because in a short space of time
you can produce a lot of seed.
you can produce a lot of seed.
96
278040
3176
04:53
Seeds are energy-rich
so there's a lot of food calories,
so there's a lot of food calories,
97
281240
2620
04:55
you can store it in times of plenty
for times of famine,
for times of famine,
98
283884
3920
05:00
but there's a downside.
99
288480
1240
05:02
The vegetative tissues,
100
290560
1376
05:03
the roots and leaves of annuals,
101
291960
2176
05:06
do not have much
102
294160
1256
05:07
by way of inherent resistance,
avoidance or tolerance characteristics.
avoidance or tolerance characteristics.
103
295440
4096
05:11
They just don't need them.
104
299560
1296
05:12
They grow in the rainy season
105
300880
1416
05:14
and they've got a seed
to help them survive the rest of the year.
to help them survive the rest of the year.
106
302320
3376
05:17
And so despite concerted
efforts in agriculture
efforts in agriculture
107
305720
2696
05:20
to make crops with improved properties
108
308440
2536
05:23
of resistance, avoidance and tolerance --
109
311000
2176
05:25
particularly resistance and avoidance
110
313200
1896
05:27
because we've had good models
to understand how those work --
to understand how those work --
111
315120
2896
05:30
we still get images like this.
112
318040
2336
05:32
Maize crop in Africa,
113
320400
1456
05:33
two weeks without rain
114
321880
1416
05:35
and it's dead.
115
323320
1200
05:37
There is a solution:
116
325560
1240
05:39
resurrection plants.
117
327520
1240
05:41
These plants can lose 95 percent
of their cellular water,
of their cellular water,
118
329320
3776
05:45
remain in a dry, dead-like state
for months to years,
for months to years,
119
333120
3856
05:49
and give them water,
120
337000
1736
05:50
they green up and start growing again.
121
338760
1880
05:53
Like seeds, these are
desiccation-tolerant.
desiccation-tolerant.
122
341560
3296
05:56
Like seeds, these can withstand extremes
of environmental conditions.
of environmental conditions.
123
344880
4120
06:01
And this is a really rare phenomenon.
124
349760
2016
06:03
There are only 135 flowering
plant species that can do this.
plant species that can do this.
125
351800
4376
06:08
I'm going to show you a video
126
356200
1416
06:09
of the resurrection process
of these three species
of these three species
127
357640
2616
06:12
in that order.
128
360280
1216
06:13
And at the bottom,
129
361520
1256
06:14
there's a time axis
so you can see how quickly it happens.
so you can see how quickly it happens.
130
362800
2736
06:56
(Applause)
131
404160
2040
07:02
Pretty amazing, huh?
132
410240
1536
07:03
So I've spent the last 21 years
trying to understand how they do this.
trying to understand how they do this.
133
411800
4216
07:08
How do these plants dry without dying?
134
416040
2400
07:11
And I work on a variety
of different resurrection plants,
of different resurrection plants,
135
419080
2776
07:13
shown here in the hydrated and dry states,
136
421880
2416
07:16
for a number of reasons.
137
424320
1456
07:17
One of them is that each
of these plants serves as a model
of these plants serves as a model
138
425800
2856
07:20
for a crop that I'd like
to make drought-tolerant.
to make drought-tolerant.
139
428680
2376
07:23
So on the extreme top left,
for example, is a grass,
for example, is a grass,
140
431080
2936
07:26
it's called Eragrostis nindensis,
141
434040
2256
07:28
it's got a close relative
called Eragrostis tef --
called Eragrostis tef --
142
436320
2376
07:30
a lot of you might know it as "teff" --
143
438720
2016
07:32
it's a staple food in Ethiopia,
144
440760
1736
07:34
it's gluten-free,
145
442520
1256
07:35
and it's something we would like
to make drought-tolerant.
to make drought-tolerant.
146
443800
3016
07:38
The other reason for looking
at a number of plants,
at a number of plants,
147
446840
2416
07:41
is that, at least initially,
148
449280
1376
07:42
I wanted to find out:
do they do the same thing?
do they do the same thing?
149
450680
2256
07:44
Do they all use the same mechanisms
150
452960
1696
07:46
to be able to lose
all that water and not die?
all that water and not die?
151
454680
2576
07:49
So I undertook what we call
a systems biology approach
a systems biology approach
152
457280
2696
07:52
in order to get
a comprehensive understanding
a comprehensive understanding
153
460000
2176
07:54
of desiccation tolerance,
154
462200
2016
07:56
in which we look at everything
155
464240
1456
07:57
from the molecular to the whole plant,
ecophysiological level.
ecophysiological level.
156
465720
2912
08:00
For example we look at things like
157
468657
1634
08:02
changes in the plant anatomy
as they dried out
as they dried out
158
470316
2197
08:04
and their ultrastructure.
159
472537
1239
08:05
We look at the transcriptome,
which is just a term for a technology
which is just a term for a technology
160
473800
3176
08:09
in which we look at the genes
161
477000
1416
08:10
that are switched on or off,
in response to drying.
in response to drying.
162
478440
2416
08:12
Most genes will code for proteins,
so we look at the proteome.
so we look at the proteome.
163
480880
3216
08:16
What are the proteins made
in response to drying?
in response to drying?
164
484120
2400
08:19
Some proteins would code for enzymes
which make metabolites,
which make metabolites,
165
487480
3896
08:23
so we look at the metabolome.
166
491400
1576
08:25
Now, this is important
because plants are stuck in the ground.
because plants are stuck in the ground.
167
493000
3296
08:28
They use what I call
a highly tuned chemical arsenal
a highly tuned chemical arsenal
168
496320
4096
08:32
to protect themselves from all
the stresses of their environment.
the stresses of their environment.
169
500440
3416
08:35
So it's important that we look
170
503880
1496
08:37
at the chemical changes
involved in drying.
involved in drying.
171
505400
2440
08:40
And at the last study
that we do at the molecular level,
that we do at the molecular level,
172
508520
2656
08:43
we look at the lipidome --
173
511200
1256
08:44
the lipid changes in response to drying.
174
512480
2055
08:46
And that's also important
175
514559
1257
08:47
because all biological membranes
are made of lipids.
are made of lipids.
176
515840
2815
08:50
They're held as membranes
because they're in water.
because they're in water.
177
518679
2577
08:53
Take away the water,
those membranes fall apart.
those membranes fall apart.
178
521280
2240
08:56
Lipids also act as signals
to turn on genes.
to turn on genes.
179
524240
3040
09:00
Then we use physiological
and biochemical studies
and biochemical studies
180
528200
2696
09:02
to try and understand
the function of the putative protectants
the function of the putative protectants
181
530920
3216
09:06
that we've actually discovered
in our other studies.
in our other studies.
182
534160
2936
09:09
And then use all of that
to try and understand
to try and understand
183
537120
2176
09:11
how the plant copes
with its natural environment.
with its natural environment.
184
539320
2320
09:15
I've always had the philosophy that
I needed a comprehensive understanding
I needed a comprehensive understanding
185
543480
4336
09:19
of the mechanisms of desiccation tolerance
186
547840
2256
09:22
in order to make a meaningful suggestion
for a biotic application.
for a biotic application.
187
550120
3840
09:27
I'm sure some of you are thinking,
188
555000
1656
09:28
"By biotic application,
189
556680
1256
09:29
does she mean she's going to make
genetically modified crops?"
genetically modified crops?"
190
557960
2920
09:34
And the answer to that question is:
191
562240
1696
09:35
depends on your definition
of genetic modification.
of genetic modification.
192
563960
2381
09:39
All of the crops that we eat today,
wheat, rice and maize,
wheat, rice and maize,
193
567200
2816
09:42
are highly genetically modified
from their ancestors,
from their ancestors,
194
570040
3216
09:45
but we don't consider them GM
195
573280
1976
09:47
because they're being produced
by conventional breeding.
by conventional breeding.
196
575280
2640
09:50
If you mean, am I going to put
resurrection plant genes into crops,
resurrection plant genes into crops,
197
578880
3776
09:54
your answer is yes.
198
582680
1296
09:56
In the essence of time,
we have tried that approach.
we have tried that approach.
199
584000
3136
09:59
More appropriately,
some of my collaborators at UCT,
some of my collaborators at UCT,
200
587160
2856
10:02
Jennifer Thomson, Suhail Rafudeen,
201
590040
1936
10:04
have spearheaded that approach
202
592000
1616
10:05
and I'm going to show you some data soon.
203
593640
1953
10:09
But we're about to embark
upon an extremely ambitious approach,
upon an extremely ambitious approach,
204
597200
4016
10:13
in which we aim to turn on
whole suites of genes
whole suites of genes
205
601240
3456
10:16
that are already present in every crop.
206
604720
2696
10:19
They're just never turned on
under extreme drought conditions.
under extreme drought conditions.
207
607440
2905
10:22
I leave it up to you to decide
208
610800
1456
10:24
whether those should be called GM or not.
209
612280
1953
10:27
I'm going to now just give you
some of the data from that first approach.
some of the data from that first approach.
210
615560
3456
10:31
And in order to do that
211
619040
1256
10:32
I have to explain a little bit
about how genes work.
about how genes work.
212
620320
2656
10:35
So you probably all know
213
623000
1256
10:36
that genes are made
of double-stranded DNA.
of double-stranded DNA.
214
624280
2056
10:38
It's wound very tightly into chromosomes
215
626360
1936
10:40
that are present in every cell
of your body or in a plant's body.
of your body or in a plant's body.
216
628320
3160
10:44
If you unwind that DNA, you get genes.
217
632080
3080
10:47
And each gene has a promoter,
218
635840
2456
10:50
which is just an on-off switch,
219
638320
2376
10:52
the gene coding region,
220
640720
1416
10:54
and then a terminator,
221
642160
1256
10:55
which indicates that this is the end
of this gene, the next gene will start.
of this gene, the next gene will start.
222
643440
3600
10:59
Now, promoters are not
simple on-off switches.
simple on-off switches.
223
647720
2896
11:02
They normally require
a lot of fine-tuning,
a lot of fine-tuning,
224
650640
2696
11:05
lots of things to be present and correct
before that gene is switched on.
before that gene is switched on.
225
653360
4040
11:10
So what's typically done
in biotech studies
in biotech studies
226
658240
3056
11:13
is that we use an inducible promoter,
227
661320
1816
11:15
we know how to switch it on.
228
663160
1576
11:16
We couple that to genes of interest
229
664760
2016
11:18
and put that into a plant
and see how the plant responds.
and see how the plant responds.
230
666800
2680
11:22
In the study that I'm going
to talk to you about,
to talk to you about,
231
670120
2576
11:24
my collaborators used
a drought-induced promoter,
a drought-induced promoter,
232
672720
2456
11:27
which we discovered
in a resurrection plant.
in a resurrection plant.
233
675200
2416
11:29
The nice thing about this promoter
is that we do nothing.
is that we do nothing.
234
677640
3136
11:32
The plant itself senses drought.
235
680800
2080
11:35
And we've used it to drive antioxidant
genes from resurrection plants.
genes from resurrection plants.
236
683600
5096
11:40
Why antioxidant genes?
237
688720
1856
11:42
Well, all stresses,
particularly drought stress,
particularly drought stress,
238
690600
3056
11:45
results in the formation of free radicals,
239
693680
2296
11:48
or reactive oxygen species,
240
696000
2336
11:50
which are highly damaging
and can cause crop death.
and can cause crop death.
241
698360
2720
11:53
What antioxidants do is stop that damage.
242
701680
2600
11:57
So here's some data from a maize strain
that's very popularly used in Africa.
that's very popularly used in Africa.
243
705360
3896
12:01
To the left of the arrow
are plants without the genes,
are plants without the genes,
244
709280
3296
12:04
to the right --
245
712600
1256
12:05
plants with the antioxidant genes.
246
713880
2056
12:07
After three weeks without watering,
247
715960
1816
12:09
the ones with the genes
do a hell of a lot better.
do a hell of a lot better.
248
717800
2480
12:13
Now to the final approach.
249
721720
1336
12:15
My research has shown
that there's considerable similarity
that there's considerable similarity
250
723080
3536
12:18
in the mechanisms of desiccation tolerance
in seeds and resurrection plants.
in seeds and resurrection plants.
251
726640
4416
12:23
So I ask the question,
252
731080
1416
12:24
are they using the same genes?
253
732520
1440
12:26
Or slightly differently phrased,
254
734480
2256
12:28
are resurrection plants using genes
evolved in seed desiccation tolerance
evolved in seed desiccation tolerance
255
736760
4496
12:33
in their roots and leaves?
256
741280
1256
12:34
Have they retasked these seed genes
257
742560
2056
12:36
in roots and leaves
of resurrection plants?
of resurrection plants?
258
744640
2040
12:39
And I answer that question,
259
747760
1856
12:41
as a consequence of a lot
of research from my group
of research from my group
260
749640
2416
12:44
and recent collaborations from a group
of Henk Hilhorst in the Netherlands,
of Henk Hilhorst in the Netherlands,
261
752080
3536
12:47
Mel Oliver in the United States
262
755640
1576
12:49
and Julia Buitink in France.
263
757240
2600
12:51
The answer is yes,
264
759880
1416
12:53
that there is a core set of genes
that are involved in both.
that are involved in both.
265
761320
2856
12:56
And I'm going to illustrate this
very crudely for maize,
very crudely for maize,
266
764200
3416
12:59
where the chromosomes below the off switch
267
767640
2416
13:02
represent all the genes that are required
for desiccation tolerance.
for desiccation tolerance.
268
770080
3575
13:05
So as maize seeds dried out
at the end of their period of development,
at the end of their period of development,
269
773680
4256
13:09
they switch these genes on.
270
777960
1360
13:12
Resurrection plants
switch on the same genes
switch on the same genes
271
780680
2896
13:15
when they dry out.
272
783600
1656
13:17
All modern crops, therefore,
273
785280
1776
13:19
have these genes
in their roots and leaves,
in their roots and leaves,
274
787080
2056
13:21
they just never switch them on.
275
789160
1736
13:22
They only switch them on in seed tissues.
276
790920
1960
13:25
So what we're trying to do right now
277
793440
1736
13:27
is to understand the environmental
and cellular signals
and cellular signals
278
795200
2616
13:29
that switch on these genes
in resurrection plants,
in resurrection plants,
279
797840
2440
13:33
to mimic the process in crops.
280
801280
1760
13:35
And just a final thought.
281
803680
1736
13:37
What we're trying to do very rapidly
282
805440
2216
13:39
is to repeat what nature did
in the evolution of resurrection plants
in the evolution of resurrection plants
283
807680
3816
13:43
some 10 to 40 million years ago.
284
811520
1840
13:46
My plants and I thank you
for your attention.
for your attention.
285
814160
2496
13:48
(Applause)
286
816680
6235
ABOUT THE SPEAKER
Jill Farrant - Professor of molecular and cell biologyJill Farrant is leading the development of drought-tolerant crops to nourish populations in arid climates.
Why you should listen
A professor of molecular and cell biology at the University of Cape Town (UCT) in South Africa, Jill Farrant researches the remarkable (and little known) world of resurrection plants. These are plants that can survive extreme drought, “resurrecting” when moistened or irrigated. If we can better understand their natural preservation mechanisms and their key protectants, she suggests, it could help us develop more drought-tolerant crops to feed populations in increasingly dry and arid climates around the world. Her research may also have medical applications.
Farrant was the African/Arab States recipient of the 2012 L'Oreal-UNESCO Award for Women in Science, one of only five scientists worldwide who were selected by an international jury as "researchers who will have a major impact on society and help light the way to the future." In 2009, she was awarded an A-rating by the National Research Foundation (the first female researcher at UCT ever to receive such a rating) as well as being made a member of the UCT College of Fellows.
Jill Farrant | Speaker | TED.com