[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.84,0:00:05.06,Default,,0000,0000,0000,,I believe that the secret to producing\Nextremely drought-tolerant crops,
Dialogue: 0,0:00:05.08,0:00:08.30,Default,,0000,0000,0000,,which should go some way\Nto providing food security in the world,
Dialogue: 0,0:00:08.32,0:00:11.02,Default,,0000,0000,0000,,lies in resurrection plants,
Dialogue: 0,0:00:11.04,0:00:14.18,Default,,0000,0000,0000,,pictured here, in an extremely\Ndroughted state.
Dialogue: 0,0:00:14.20,0:00:17.06,Default,,0000,0000,0000,,Now, you might think\Nthat these plants look dead,
Dialogue: 0,0:00:17.08,0:00:18.38,Default,,0000,0000,0000,,but they're not.
Dialogue: 0,0:00:18.40,0:00:19.86,Default,,0000,0000,0000,,Give them water,
Dialogue: 0,0:00:19.88,0:00:25.32,Default,,0000,0000,0000,,and they will resurrect, green up,\Nstart growing, in 12 to 48 hours.
Dialogue: 0,0:00:26.32,0:00:27.62,Default,,0000,0000,0000,,Now, why would I suggest
Dialogue: 0,0:00:27.64,0:00:32.08,Default,,0000,0000,0000,,that producing drought-tolerant crops\Nwill go towards providing food security?
Dialogue: 0,0:00:33.04,0:00:36.94,Default,,0000,0000,0000,,Well, the current world population\Nis around 7 billion.
Dialogue: 0,0:00:36.96,0:00:39.46,Default,,0000,0000,0000,,And it's estimated that by 2050,
Dialogue: 0,0:00:39.48,0:00:42.18,Default,,0000,0000,0000,,we'll be between 9 and 10 billion people,
Dialogue: 0,0:00:42.20,0:00:45.08,Default,,0000,0000,0000,,with the bulk of this growth\Nhappening in Africa.
Dialogue: 0,0:00:45.88,0:00:48.34,Default,,0000,0000,0000,,The food and agricultural\Norganizations of the world
Dialogue: 0,0:00:48.36,0:00:51.50,Default,,0000,0000,0000,,have suggested that we need\Na 70 percent increase
Dialogue: 0,0:00:51.52,0:00:53.70,Default,,0000,0000,0000,,in current agricultural practice
Dialogue: 0,0:00:53.72,0:00:54.96,Default,,0000,0000,0000,,to meet that demand.
Dialogue: 0,0:00:55.72,0:00:58.42,Default,,0000,0000,0000,,Now, given that plants\Nare at the base of the food chain,
Dialogue: 0,0:00:58.44,0:01:00.76,Default,,0000,0000,0000,,most of that's going\Nto have to come from plants.
Dialogue: 0,0:01:01.36,0:01:04.06,Default,,0000,0000,0000,,Now, that percentage of 70 percent
Dialogue: 0,0:01:04.08,0:01:08.30,Default,,0000,0000,0000,,does not take into consideration\Nthe potential effects of climate change.
Dialogue: 0,0:01:08.32,0:01:12.56,Default,,0000,0000,0000,,This is taken from a study by Dye\Npublished in 2011,
Dialogue: 0,0:01:13.24,0:01:15.18,Default,,0000,0000,0000,,where he took into consideration
Dialogue: 0,0:01:15.20,0:01:17.58,Default,,0000,0000,0000,,all the potential effects\Nof climate change
Dialogue: 0,0:01:17.60,0:01:19.74,Default,,0000,0000,0000,,and expressed them --\Namongst other things --
Dialogue: 0,0:01:19.76,0:01:24.38,Default,,0000,0000,0000,,increased aridity due to lack of rain\Nor infrequent rain.
Dialogue: 0,0:01:24.40,0:01:26.18,Default,,0000,0000,0000,,Now, the areas in red shown here,
Dialogue: 0,0:01:26.20,0:01:28.26,Default,,0000,0000,0000,,are areas that until recently
Dialogue: 0,0:01:28.28,0:01:31.46,Default,,0000,0000,0000,,have been very successfully\Nused for agriculture,
Dialogue: 0,0:01:31.48,0:01:33.88,Default,,0000,0000,0000,,but cannot anymore\Nbecause of lack of rainfall.
Dialogue: 0,0:01:34.64,0:01:37.56,Default,,0000,0000,0000,,This is the situation\Nthat's predicted to happen in 2050.
Dialogue: 0,0:01:38.84,0:01:41.02,Default,,0000,0000,0000,,Much of Africa,\Nin fact, much of the world,
Dialogue: 0,0:01:41.04,0:01:42.94,Default,,0000,0000,0000,,is going to be in trouble.
Dialogue: 0,0:01:42.96,0:01:46.62,Default,,0000,0000,0000,,We're going to have to think of some\Nvery smart ways of producing food.
Dialogue: 0,0:01:46.64,0:01:49.94,Default,,0000,0000,0000,,And preferably among them,\Nsome drought-tolerant crops.
Dialogue: 0,0:01:49.96,0:01:52.02,Default,,0000,0000,0000,,The other thing\Nto remember about Africa is
Dialogue: 0,0:01:52.04,0:01:54.84,Default,,0000,0000,0000,,that most of the agriculture is rainfed.
Dialogue: 0,0:01:56.08,0:01:59.54,Default,,0000,0000,0000,,Now, making drought-tolerant crops\Nis not the easiest thing in the world.
Dialogue: 0,0:01:59.56,0:02:01.98,Default,,0000,0000,0000,,And the reason for this is water.
Dialogue: 0,0:02:02.00,0:02:05.14,Default,,0000,0000,0000,,Water is essential to life on this planet.
Dialogue: 0,0:02:05.16,0:02:09.30,Default,,0000,0000,0000,,All living, actively\Nmetabolizing organisms,
Dialogue: 0,0:02:09.32,0:02:11.38,Default,,0000,0000,0000,,from microbes to you and I,
Dialogue: 0,0:02:11.40,0:02:13.74,Default,,0000,0000,0000,,are comprised predominately of water,
Dialogue: 0,0:02:13.76,0:02:16.30,Default,,0000,0000,0000,,all life reactions happen in water,
Dialogue: 0,0:02:16.32,0:02:19.34,Default,,0000,0000,0000,,and loss of a small amount\Nof water results in death.
Dialogue: 0,0:02:19.36,0:02:21.42,Default,,0000,0000,0000,,You and I are 65 percent water,
Dialogue: 0,0:02:21.44,0:02:23.16,Default,,0000,0000,0000,,we lose one percent of that, we die.
Dialogue: 0,0:02:23.84,0:02:26.56,Default,,0000,0000,0000,,But we can make behavioral\Nchanges to avoid that.
Dialogue: 0,0:02:27.92,0:02:29.50,Default,,0000,0000,0000,,Plants can't.
Dialogue: 0,0:02:29.52,0:02:31.14,Default,,0000,0000,0000,,They're stuck in the ground.
Dialogue: 0,0:02:31.16,0:02:34.54,Default,,0000,0000,0000,,And so in the first instance they have\Na little bit more water than us,
Dialogue: 0,0:02:34.56,0:02:35.82,Default,,0000,0000,0000,,about 95 percent water,
Dialogue: 0,0:02:35.84,0:02:37.94,Default,,0000,0000,0000,,and they can lose\Na little bit more than us,
Dialogue: 0,0:02:37.96,0:02:40.92,Default,,0000,0000,0000,,like 10 to about 70 percent,\Ndepending on the species,
Dialogue: 0,0:02:42.00,0:02:43.36,Default,,0000,0000,0000,,but for short periods only.
Dialogue: 0,0:02:44.68,0:02:48.86,Default,,0000,0000,0000,,Most of them will either try\Nto resist or avoid water loss.
Dialogue: 0,0:02:48.88,0:02:52.82,Default,,0000,0000,0000,,So extreme examples of resistors\Ncan be found in succulents,
Dialogue: 0,0:02:52.84,0:02:55.66,Default,,0000,0000,0000,,they tend to be small, very attractive,
Dialogue: 0,0:02:55.68,0:02:58.42,Default,,0000,0000,0000,,but they hold onto their water\Nat such great cost
Dialogue: 0,0:02:58.44,0:03:00.44,Default,,0000,0000,0000,,that they grow extremely slowly.
Dialogue: 0,0:03:01.44,0:03:06.02,Default,,0000,0000,0000,,Examples of avoidance of water loss\Nare found in trees and shrubs.
Dialogue: 0,0:03:06.04,0:03:07.62,Default,,0000,0000,0000,,They send down very deep roots,
Dialogue: 0,0:03:07.64,0:03:09.34,Default,,0000,0000,0000,,mine subterranean water supplies,
Dialogue: 0,0:03:09.36,0:03:11.82,Default,,0000,0000,0000,,and just keep flushing\Nit through them at all times,
Dialogue: 0,0:03:11.84,0:03:13.70,Default,,0000,0000,0000,,keeping themselves hydrated.
Dialogue: 0,0:03:13.72,0:03:15.70,Default,,0000,0000,0000,,The one on the right is called a baobab,
Dialogue: 0,0:03:15.72,0:03:17.78,Default,,0000,0000,0000,,it's also called the upside-down tree,
Dialogue: 0,0:03:17.80,0:03:21.58,Default,,0000,0000,0000,,simply because the proportion\Nof roots to shoots is so great
Dialogue: 0,0:03:21.60,0:03:24.30,Default,,0000,0000,0000,,that it looks like the tree\Nhas been planted upside down.
Dialogue: 0,0:03:24.32,0:03:27.56,Default,,0000,0000,0000,,And of course the roots are required\Nfor hydration of that plant.
Dialogue: 0,0:03:28.76,0:03:33.28,Default,,0000,0000,0000,,And probably the most common strategy\Nof avoidance is found in annuals.
Dialogue: 0,0:03:33.84,0:03:37.02,Default,,0000,0000,0000,,Annuals make up the bulk\Nof our plant food supplies.
Dialogue: 0,0:03:37.04,0:03:38.74,Default,,0000,0000,0000,,Up the west coast of my country,
Dialogue: 0,0:03:38.76,0:03:42.30,Default,,0000,0000,0000,,for much of the year\Nyou don't see much vegetation growth.
Dialogue: 0,0:03:42.32,0:03:44.98,Default,,0000,0000,0000,,But come the spring rains, you get this.
Dialogue: 0,0:03:45.00,0:03:46.24,Default,,0000,0000,0000,,Flowering of the desert.
Dialogue: 0,0:03:47.00,0:03:48.86,Default,,0000,0000,0000,,Now, the strategy in annuals,
Dialogue: 0,0:03:48.88,0:03:51.24,Default,,0000,0000,0000,,is to grow only in the rainy season.
Dialogue: 0,0:03:51.96,0:03:54.26,Default,,0000,0000,0000,,At the end of that season\Nthey produce a seed,
Dialogue: 0,0:03:54.28,0:03:57.10,Default,,0000,0000,0000,,which is dry, eight to 10 percent water,
Dialogue: 0,0:03:57.12,0:03:58.78,Default,,0000,0000,0000,,but very much alive.
Dialogue: 0,0:03:58.80,0:04:01.70,Default,,0000,0000,0000,,And anything that is\Nthat dry and still alive,
Dialogue: 0,0:04:01.72,0:04:03.20,Default,,0000,0000,0000,,we call desiccation-tolerant.
Dialogue: 0,0:04:03.84,0:04:05.26,Default,,0000,0000,0000,,Now, in the desiccated state,
Dialogue: 0,0:04:05.28,0:04:07.94,Default,,0000,0000,0000,,what seeds can do\Nis lie in extremes of environment
Dialogue: 0,0:04:07.96,0:04:09.62,Default,,0000,0000,0000,,for prolonged periods of time.
Dialogue: 0,0:04:09.64,0:04:11.86,Default,,0000,0000,0000,,The next time the rainy season comes,
Dialogue: 0,0:04:11.88,0:04:13.38,Default,,0000,0000,0000,,they germinate and grow,
Dialogue: 0,0:04:13.40,0:04:15.28,Default,,0000,0000,0000,,and the whole cycle just starts again.
Dialogue: 0,0:04:16.12,0:04:20.18,Default,,0000,0000,0000,,It's widely believed that the evolution\Nof desiccation-tolerant seeds
Dialogue: 0,0:04:20.20,0:04:22.38,Default,,0000,0000,0000,,allowed the colonization and the radiation
Dialogue: 0,0:04:22.40,0:04:25.92,Default,,0000,0000,0000,,of flowering plants,\Nor angiosperms, onto land.
Dialogue: 0,0:04:26.96,0:04:30.12,Default,,0000,0000,0000,,But back to annuals\Nas our major form of food supplies.
Dialogue: 0,0:04:30.80,0:04:35.52,Default,,0000,0000,0000,,Wheat, rice and maize form 95 percent\Nof our plant food supplies.
Dialogue: 0,0:04:36.48,0:04:38.02,Default,,0000,0000,0000,,And it's been a great strategy
Dialogue: 0,0:04:38.04,0:04:41.22,Default,,0000,0000,0000,,because in a short space of time\Nyou can produce a lot of seed.
Dialogue: 0,0:04:41.24,0:04:43.86,Default,,0000,0000,0000,,Seeds are energy-rich\Nso there's a lot of food calories,
Dialogue: 0,0:04:43.88,0:04:47.80,Default,,0000,0000,0000,,you can store it in times of plenty\Nfor times of famine,
Dialogue: 0,0:04:48.48,0:04:49.72,Default,,0000,0000,0000,,but there's a downside.
Dialogue: 0,0:04:50.56,0:04:51.94,Default,,0000,0000,0000,,The vegetative tissues --
Dialogue: 0,0:04:51.96,0:04:54.14,Default,,0000,0000,0000,,the roots and leaves of annuals --
Dialogue: 0,0:04:54.16,0:04:55.42,Default,,0000,0000,0000,,do not have much
Dialogue: 0,0:04:55.44,0:04:59.54,Default,,0000,0000,0000,,by way of inherent resistance,\Navoidance or tolerance characteristics.
Dialogue: 0,0:04:59.56,0:05:00.86,Default,,0000,0000,0000,,They just don't need them.
Dialogue: 0,0:05:00.88,0:05:02.30,Default,,0000,0000,0000,,They grow in the rainy season
Dialogue: 0,0:05:02.32,0:05:05.70,Default,,0000,0000,0000,,and they've got a seed\Nto help them survive the rest of the year.
Dialogue: 0,0:05:05.72,0:05:08.42,Default,,0000,0000,0000,,And so despite concerted\Nefforts in agriculture
Dialogue: 0,0:05:08.44,0:05:10.98,Default,,0000,0000,0000,,to make crops with improved properties
Dialogue: 0,0:05:11.00,0:05:13.18,Default,,0000,0000,0000,,of resistance, avoidance and tolerance --
Dialogue: 0,0:05:13.20,0:05:15.10,Default,,0000,0000,0000,,particularly resistance and avoidance
Dialogue: 0,0:05:15.12,0:05:18.02,Default,,0000,0000,0000,,because we've had good models\Nto understand how those work --
Dialogue: 0,0:05:18.04,0:05:20.38,Default,,0000,0000,0000,,we still get images like this.
Dialogue: 0,0:05:20.40,0:05:21.86,Default,,0000,0000,0000,,Maize crop in Africa,
Dialogue: 0,0:05:21.88,0:05:23.30,Default,,0000,0000,0000,,two weeks without rain,
Dialogue: 0,0:05:23.32,0:05:24.52,Default,,0000,0000,0000,,and it's dead.
Dialogue: 0,0:05:25.56,0:05:26.80,Default,,0000,0000,0000,,Now, there is a solution.
Dialogue: 0,0:05:27.52,0:05:28.76,Default,,0000,0000,0000,,Resurrection plants.
Dialogue: 0,0:05:29.32,0:05:33.10,Default,,0000,0000,0000,,These plants can lose 95 percent\Nof their cellular water,
Dialogue: 0,0:05:33.12,0:05:36.98,Default,,0000,0000,0000,,remain in a dry, dead-like state\Nfor months to years,
Dialogue: 0,0:05:37.00,0:05:38.74,Default,,0000,0000,0000,,and give them water,
Dialogue: 0,0:05:38.76,0:05:40.64,Default,,0000,0000,0000,,they green up and start growing again.
Dialogue: 0,0:05:41.56,0:05:44.86,Default,,0000,0000,0000,,Like seeds, these are\Ndesiccation-tolerant.
Dialogue: 0,0:05:44.88,0:05:49.00,Default,,0000,0000,0000,,Like seeds, these can withstand extremes\Nof environmental conditions.
Dialogue: 0,0:05:49.76,0:05:51.78,Default,,0000,0000,0000,,And this is a really rare phenomenon.
Dialogue: 0,0:05:51.80,0:05:56.18,Default,,0000,0000,0000,,There are only 135 flowering\Nplant species that can do this.
Dialogue: 0,0:05:56.20,0:05:57.62,Default,,0000,0000,0000,,I'm going to show you a video
Dialogue: 0,0:05:57.64,0:06:00.26,Default,,0000,0000,0000,,of the resurrection process\Nof these three species
Dialogue: 0,0:06:00.28,0:06:01.50,Default,,0000,0000,0000,,in that order.
Dialogue: 0,0:06:01.52,0:06:02.78,Default,,0000,0000,0000,,And at the bottom,
Dialogue: 0,0:06:02.80,0:06:05.54,Default,,0000,0000,0000,,there's a time axis\Nso you can see how quickly it happens.
Dialogue: 0,0:06:05.56,0:06:06.76,Default,,0000,0000,0000,,[Video]
Dialogue: 0,0:06:44.16,0:06:46.20,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:06:50.24,0:06:51.78,Default,,0000,0000,0000,,Pretty amazing, huh?
Dialogue: 0,0:06:51.80,0:06:56.02,Default,,0000,0000,0000,,So I've spent the last 21 years\Ntrying to understand how they do this.
Dialogue: 0,0:06:56.04,0:06:58.44,Default,,0000,0000,0000,,How do these plants dry without dying?
Dialogue: 0,0:06:59.08,0:07:01.86,Default,,0000,0000,0000,,And I work on a variety\Nof different resurrection plants,
Dialogue: 0,0:07:01.88,0:07:04.30,Default,,0000,0000,0000,,shown here in the hydrated and dry states,
Dialogue: 0,0:07:04.32,0:07:05.78,Default,,0000,0000,0000,,for a number of reasons.
Dialogue: 0,0:07:05.80,0:07:08.66,Default,,0000,0000,0000,,One of them is that each\Nof these plants serves as a model
Dialogue: 0,0:07:08.68,0:07:11.06,Default,,0000,0000,0000,,for a crop that I'd like\Nto make drought-tolerant.
Dialogue: 0,0:07:11.08,0:07:14.02,Default,,0000,0000,0000,,So on the extreme top left,\Nfor example, is a grass,
Dialogue: 0,0:07:14.04,0:07:16.30,Default,,0000,0000,0000,,it's called Eragrostis nindensis,
Dialogue: 0,0:07:16.32,0:07:18.70,Default,,0000,0000,0000,,it's got a close relative\Ncalled Eragrostis tef --
Dialogue: 0,0:07:18.72,0:07:20.74,Default,,0000,0000,0000,,a lot of you might know it as "teff" --
Dialogue: 0,0:07:20.76,0:07:22.50,Default,,0000,0000,0000,,it's a staple food in Ethiopia,
Dialogue: 0,0:07:22.52,0:07:23.78,Default,,0000,0000,0000,,it's gluten-free,
Dialogue: 0,0:07:23.80,0:07:26.82,Default,,0000,0000,0000,,and it's something we would like\Nto make drought-tolerant.
Dialogue: 0,0:07:26.84,0:07:29.26,Default,,0000,0000,0000,,The other reason for looking\Nat a number of plants,
Dialogue: 0,0:07:29.28,0:07:30.66,Default,,0000,0000,0000,,is that, as least initially,
Dialogue: 0,0:07:30.68,0:07:32.94,Default,,0000,0000,0000,,I wanted to find out:\Ndo they do the same thing?
Dialogue: 0,0:07:32.96,0:07:34.66,Default,,0000,0000,0000,,Do they all use the same mechanisms
Dialogue: 0,0:07:34.68,0:07:37.26,Default,,0000,0000,0000,,to be able to lose\Nall that water and not die?
Dialogue: 0,0:07:37.28,0:07:39.98,Default,,0000,0000,0000,,So I undertook what we call\Na systems biology approach
Dialogue: 0,0:07:40.00,0:07:42.18,Default,,0000,0000,0000,,in order to get\Na comprehensive understanding
Dialogue: 0,0:07:42.20,0:07:44.22,Default,,0000,0000,0000,,of desiccation tolerance,
Dialogue: 0,0:07:44.24,0:07:45.70,Default,,0000,0000,0000,,in which we look at everything
Dialogue: 0,0:07:45.72,0:07:48.63,Default,,0000,0000,0000,,from the molecular to the whole plant,\Necophysiological level.
Dialogue: 0,0:07:48.66,0:07:50.29,Default,,0000,0000,0000,,For example we look at things like
Dialogue: 0,0:07:50.32,0:07:52.51,Default,,0000,0000,0000,,changes in the plant anatomy\Nas they dried out,
Dialogue: 0,0:07:52.54,0:07:53.78,Default,,0000,0000,0000,,and their ultrastructure.
Dialogue: 0,0:07:53.80,0:07:56.98,Default,,0000,0000,0000,,We look at the transcriptome,\Nwhich is just a term for a technology
Dialogue: 0,0:07:57.00,0:07:58.42,Default,,0000,0000,0000,,in which we look at the genes
Dialogue: 0,0:07:58.44,0:08:00.86,Default,,0000,0000,0000,,that are switched on or off,\Nin response to drying.
Dialogue: 0,0:08:00.88,0:08:04.10,Default,,0000,0000,0000,,Most genes will code for proteins\Nso we look at the proteome.
Dialogue: 0,0:08:04.12,0:08:06.52,Default,,0000,0000,0000,,What are the proteins made\Nin response to drying?
Dialogue: 0,0:08:07.48,0:08:11.38,Default,,0000,0000,0000,,Some proteins would code for enzymes\Nwhich make metabolites,
Dialogue: 0,0:08:11.40,0:08:12.98,Default,,0000,0000,0000,,so we look at the metabolome.
Dialogue: 0,0:08:13.00,0:08:16.30,Default,,0000,0000,0000,,Now, this is important\Nbecause plants are stuck in the ground.
Dialogue: 0,0:08:16.32,0:08:20.42,Default,,0000,0000,0000,,They use what I call\Na highly tuned chemical arsenal
Dialogue: 0,0:08:20.44,0:08:23.86,Default,,0000,0000,0000,,to protect themselves from all\Nthe stresses of their environment.
Dialogue: 0,0:08:23.88,0:08:25.38,Default,,0000,0000,0000,,So it's important that we look
Dialogue: 0,0:08:25.40,0:08:27.84,Default,,0000,0000,0000,,at the chemical changes\Ninvolved in drying.
Dialogue: 0,0:08:28.52,0:08:31.18,Default,,0000,0000,0000,,And at the last study\Nthat we do at the molecular level,
Dialogue: 0,0:08:31.20,0:08:32.46,Default,,0000,0000,0000,,we look at the lipidome --
Dialogue: 0,0:08:32.48,0:08:34.54,Default,,0000,0000,0000,,the lipid changes in response to drying.
Dialogue: 0,0:08:34.56,0:08:35.82,Default,,0000,0000,0000,,And that's also important
Dialogue: 0,0:08:35.84,0:08:38.66,Default,,0000,0000,0000,,because all biological membranes\Nare made of lipids.
Dialogue: 0,0:08:38.68,0:08:41.26,Default,,0000,0000,0000,,They're held as membranes\Nbecause they're in water.
Dialogue: 0,0:08:41.28,0:08:43.52,Default,,0000,0000,0000,,Take away the water,\Nthose membranes fall apart.
Dialogue: 0,0:08:44.24,0:08:47.28,Default,,0000,0000,0000,,Lipids also act as signals\Nto turn on genes.
Dialogue: 0,0:08:48.20,0:08:50.90,Default,,0000,0000,0000,,Then we use physiological\Nand biochemical studies
Dialogue: 0,0:08:50.92,0:08:54.14,Default,,0000,0000,0000,,to try and understand\Nthe function of the putative protectants
Dialogue: 0,0:08:54.16,0:08:57.10,Default,,0000,0000,0000,,that we've actually discovered\Nin our other studies.
Dialogue: 0,0:08:57.12,0:08:59.30,Default,,0000,0000,0000,,And then use all of that\Nto try and understand
Dialogue: 0,0:08:59.32,0:09:01.64,Default,,0000,0000,0000,,how the plant copes\Nwith its natural environment.
Dialogue: 0,0:09:03.48,0:09:07.82,Default,,0000,0000,0000,,Now, I've always had the philosophy that\NI needed a comprehensive understanding
Dialogue: 0,0:09:07.84,0:09:10.10,Default,,0000,0000,0000,,of the mechanisms of desiccation tolerance
Dialogue: 0,0:09:10.12,0:09:13.96,Default,,0000,0000,0000,,in order to make a meaningful suggestion\Nfor a biotic application.
Dialogue: 0,0:09:15.00,0:09:16.66,Default,,0000,0000,0000,,I'm sure some of you are thinking,
Dialogue: 0,0:09:16.68,0:09:17.94,Default,,0000,0000,0000,,"by biotic application,
Dialogue: 0,0:09:17.96,0:09:20.88,Default,,0000,0000,0000,,does she mean she's going to make\Ngenetically modified crops?"
Dialogue: 0,0:09:22.24,0:09:23.94,Default,,0000,0000,0000,,And the answer to that question is:
Dialogue: 0,0:09:23.96,0:09:26.34,Default,,0000,0000,0000,,depends on your definition\Nof genetic modification.
Dialogue: 0,0:09:27.20,0:09:30.02,Default,,0000,0000,0000,,All of the crops that we eat today,\Nwheat, grass and maize,
Dialogue: 0,0:09:30.04,0:09:33.26,Default,,0000,0000,0000,,are highly genetically modified\Nfrom their ancestors,
Dialogue: 0,0:09:33.28,0:09:35.26,Default,,0000,0000,0000,,but we don't consider them GM,
Dialogue: 0,0:09:35.28,0:09:37.92,Default,,0000,0000,0000,,because they're being produced\Nby conventional breeding.
Dialogue: 0,0:09:38.88,0:09:42.66,Default,,0000,0000,0000,,If you mean, am I going to put\Nresurrection plant genes into crops,
Dialogue: 0,0:09:42.68,0:09:43.98,Default,,0000,0000,0000,,your answer is yes.
Dialogue: 0,0:09:44.00,0:09:47.14,Default,,0000,0000,0000,,In the essence of time,\Nwe have tried that approach.
Dialogue: 0,0:09:47.16,0:09:50.02,Default,,0000,0000,0000,,More appropriately,\Nsome of my collaborators at UCT,
Dialogue: 0,0:09:50.04,0:09:51.98,Default,,0000,0000,0000,,Jennifer Thomson, Suhail Rafudeen,
Dialogue: 0,0:09:52.00,0:09:53.62,Default,,0000,0000,0000,,have spearheaded that approach
Dialogue: 0,0:09:53.64,0:09:55.59,Default,,0000,0000,0000,,and I'm going to show you some data soon.
Dialogue: 0,0:09:57.20,0:10:01.22,Default,,0000,0000,0000,,But we're about to embark\Nupon an extremely ambitious approach,
Dialogue: 0,0:10:01.24,0:10:04.70,Default,,0000,0000,0000,,in which we aim to turn on\Nwhole suites of genes
Dialogue: 0,0:10:04.72,0:10:07.42,Default,,0000,0000,0000,,that are already present in every crop.
Dialogue: 0,0:10:07.44,0:10:10.34,Default,,0000,0000,0000,,They're just never turned on\Nunder extreme drought conditions.
Dialogue: 0,0:10:10.80,0:10:12.26,Default,,0000,0000,0000,,I leave it up to you to decide
Dialogue: 0,0:10:12.28,0:10:14.23,Default,,0000,0000,0000,,whether those should be called GM or not.
Dialogue: 0,0:10:15.56,0:10:19.02,Default,,0000,0000,0000,,I'm going to now just give you\Nsome of the data from that first approach.
Dialogue: 0,0:10:19.04,0:10:20.30,Default,,0000,0000,0000,,And in order to do that
Dialogue: 0,0:10:20.32,0:10:22.98,Default,,0000,0000,0000,,I have to explain a little bit\Nabout how genes work.
Dialogue: 0,0:10:23.00,0:10:24.26,Default,,0000,0000,0000,,So you probably all know
Dialogue: 0,0:10:24.28,0:10:26.34,Default,,0000,0000,0000,,that genes are made\Nof double-stranded DNA.
Dialogue: 0,0:10:26.36,0:10:28.30,Default,,0000,0000,0000,,It's wound very tightly into chromosomes
Dialogue: 0,0:10:28.32,0:10:31.48,Default,,0000,0000,0000,,that are present in every cell\Nof your body or in a plant's body.
Dialogue: 0,0:10:32.08,0:10:35.16,Default,,0000,0000,0000,,If you unwind that DNA, you get genes.
Dialogue: 0,0:10:35.84,0:10:38.30,Default,,0000,0000,0000,,And each gene has a promoter,
Dialogue: 0,0:10:38.32,0:10:40.70,Default,,0000,0000,0000,,which is just an on-off switch,
Dialogue: 0,0:10:40.72,0:10:42.14,Default,,0000,0000,0000,,the gene coding region,
Dialogue: 0,0:10:42.16,0:10:43.42,Default,,0000,0000,0000,,and then a terminator,
Dialogue: 0,0:10:43.44,0:10:47.04,Default,,0000,0000,0000,,which indicates that this is the end\Nof this gene, the next gene will start.
Dialogue: 0,0:10:47.72,0:10:50.62,Default,,0000,0000,0000,,Now, promoters are not\Nsimple on-off switches.
Dialogue: 0,0:10:50.64,0:10:53.34,Default,,0000,0000,0000,,They normally require\Na lot of fine-tuning,
Dialogue: 0,0:10:53.36,0:10:57.40,Default,,0000,0000,0000,,lots of things to be present and correct\Nbefore that gene is switched on.
Dialogue: 0,0:10:58.24,0:11:01.30,Default,,0000,0000,0000,,So what's typically done\Nin biotech studies
Dialogue: 0,0:11:01.32,0:11:03.14,Default,,0000,0000,0000,,is that we use an inducible promoter,
Dialogue: 0,0:11:03.16,0:11:04.74,Default,,0000,0000,0000,,we know how to switch it on.
Dialogue: 0,0:11:04.76,0:11:06.78,Default,,0000,0000,0000,,We couple that to genes of interest,
Dialogue: 0,0:11:06.80,0:11:09.48,Default,,0000,0000,0000,,and put that into a plant\Nand see how the plant responds.
Dialogue: 0,0:11:10.12,0:11:12.70,Default,,0000,0000,0000,,Now, in the study that I'm going\Nto talk to you about,
Dialogue: 0,0:11:12.72,0:11:15.18,Default,,0000,0000,0000,,my collaborators used\Na drought-induced promoter,
Dialogue: 0,0:11:15.20,0:11:17.62,Default,,0000,0000,0000,,which we discovered\Nin a resurrection plant.
Dialogue: 0,0:11:17.64,0:11:20.78,Default,,0000,0000,0000,,Now, the nice thing about this promoter\Nis that we do nothing.
Dialogue: 0,0:11:20.80,0:11:22.88,Default,,0000,0000,0000,,The plant itself senses drought.
Dialogue: 0,0:11:23.60,0:11:28.70,Default,,0000,0000,0000,,And we've used it to drive antioxidant\Ngenes from resurrection plants.
Dialogue: 0,0:11:28.72,0:11:30.58,Default,,0000,0000,0000,,Why antioxidant genes?
Dialogue: 0,0:11:30.60,0:11:33.66,Default,,0000,0000,0000,,Well, all stresses,\Nparticularly drought stress,
Dialogue: 0,0:11:33.68,0:11:35.98,Default,,0000,0000,0000,,results in the formation of free radicals,
Dialogue: 0,0:11:36.00,0:11:38.34,Default,,0000,0000,0000,,or reactive oxygen species,
Dialogue: 0,0:11:38.36,0:11:41.08,Default,,0000,0000,0000,,which are highly damaging\Nand can cause crop death.
Dialogue: 0,0:11:41.68,0:11:44.28,Default,,0000,0000,0000,,What antioxidants do is stop that damage.
Dialogue: 0,0:11:45.36,0:11:49.26,Default,,0000,0000,0000,,So here's some data from a main strain\Nthat's very popularly used in Africa.
Dialogue: 0,0:11:49.28,0:11:52.58,Default,,0000,0000,0000,,To the left of the arrow\Nare plants without the genes,
Dialogue: 0,0:11:52.60,0:11:53.86,Default,,0000,0000,0000,,to the right --
Dialogue: 0,0:11:53.88,0:11:55.94,Default,,0000,0000,0000,,plants with the antioxidant genes.
Dialogue: 0,0:11:55.96,0:11:57.78,Default,,0000,0000,0000,,After three weeks without watering,
Dialogue: 0,0:11:57.80,0:12:00.28,Default,,0000,0000,0000,,the ones with the genes\Ndo a hell of a lot better.
Dialogue: 0,0:12:01.72,0:12:03.06,Default,,0000,0000,0000,,Now, to the final approach.
Dialogue: 0,0:12:03.08,0:12:06.62,Default,,0000,0000,0000,,My research has shown\Nthat there's considerable similarity
Dialogue: 0,0:12:06.64,0:12:11.06,Default,,0000,0000,0000,,in the mechanisms of desiccation tolerance\Nin seeds and resurrection plants.
Dialogue: 0,0:12:11.08,0:12:12.50,Default,,0000,0000,0000,,So I ask the question,
Dialogue: 0,0:12:12.52,0:12:13.96,Default,,0000,0000,0000,,are they using the same genes?
Dialogue: 0,0:12:14.48,0:12:16.74,Default,,0000,0000,0000,,Or slightly differently phrased,
Dialogue: 0,0:12:16.76,0:12:21.26,Default,,0000,0000,0000,,are resurrection plants using genes\Nevolved in seed desiccation tolerance
Dialogue: 0,0:12:21.28,0:12:22.54,Default,,0000,0000,0000,,in their roots and leaves?
Dialogue: 0,0:12:22.56,0:12:24.62,Default,,0000,0000,0000,,Have they retasked these seed genes
Dialogue: 0,0:12:24.64,0:12:26.68,Default,,0000,0000,0000,,in roots and leaves\Nof resurrection plants?
Dialogue: 0,0:12:27.76,0:12:29.62,Default,,0000,0000,0000,,And I answer that question,
Dialogue: 0,0:12:29.64,0:12:32.06,Default,,0000,0000,0000,,as a consequence of a lot\Nof research from my group
Dialogue: 0,0:12:32.08,0:12:35.62,Default,,0000,0000,0000,,and recent collaborations from a group\Nof Henk Hilhorst in the Netherlands,
Dialogue: 0,0:12:35.64,0:12:37.22,Default,,0000,0000,0000,,Mel Oliver in the United States,
Dialogue: 0,0:12:37.24,0:12:39.84,Default,,0000,0000,0000,,and Julia Buitink, in France.
Dialogue: 0,0:12:39.88,0:12:41.30,Default,,0000,0000,0000,,The answer is yes,
Dialogue: 0,0:12:41.32,0:12:44.18,Default,,0000,0000,0000,,that there is a core set of genes\Nthat are involved in both.
Dialogue: 0,0:12:44.20,0:12:47.62,Default,,0000,0000,0000,,And I'm going to illustrate this\Nvery crudely for maize,
Dialogue: 0,0:12:47.64,0:12:50.06,Default,,0000,0000,0000,,where the chromosomes below the off switch
Dialogue: 0,0:12:50.08,0:12:53.66,Default,,0000,0000,0000,,represent all the genes that are required\Nfor desiccation tolerance.
Dialogue: 0,0:12:53.68,0:12:57.94,Default,,0000,0000,0000,,So as maize seeds dried out\Nat the end of their period of development,
Dialogue: 0,0:12:57.96,0:12:59.32,Default,,0000,0000,0000,,they switch these genes on.
Dialogue: 0,0:13:00.68,0:13:03.58,Default,,0000,0000,0000,,Resurrection plants\Nswitch on the same genes
Dialogue: 0,0:13:03.60,0:13:05.26,Default,,0000,0000,0000,,when they dry out.
Dialogue: 0,0:13:05.28,0:13:07.06,Default,,0000,0000,0000,,All modern crops, therefore,
Dialogue: 0,0:13:07.08,0:13:09.14,Default,,0000,0000,0000,,have these genes\Nin their roots and leaves,
Dialogue: 0,0:13:09.16,0:13:10.90,Default,,0000,0000,0000,,they just never switch them on.
Dialogue: 0,0:13:10.92,0:13:12.88,Default,,0000,0000,0000,,They only switch them on in seed tissues.
Dialogue: 0,0:13:13.44,0:13:15.18,Default,,0000,0000,0000,,So what we're trying to do right now
Dialogue: 0,0:13:15.20,0:13:17.82,Default,,0000,0000,0000,,is to understand the environmental\Nand cellular signals
Dialogue: 0,0:13:17.84,0:13:20.28,Default,,0000,0000,0000,,that switch on these genes\Nin resurrection plants,
Dialogue: 0,0:13:21.28,0:13:23.04,Default,,0000,0000,0000,,to mimic the process in crops.
Dialogue: 0,0:13:23.68,0:13:25.42,Default,,0000,0000,0000,,And just a final thought.
Dialogue: 0,0:13:25.44,0:13:27.66,Default,,0000,0000,0000,,What we're trying to do very rapidly,
Dialogue: 0,0:13:27.68,0:13:31.50,Default,,0000,0000,0000,,is to repeat what nature did\Nin the evolution of resurrection plants
Dialogue: 0,0:13:31.52,0:13:33.36,Default,,0000,0000,0000,,some 10 to 40 million years ago.
Dialogue: 0,0:13:34.16,0:13:36.66,Default,,0000,0000,0000,,My plants and I thank you\Nfor your attention.
Dialogue: 0,0:13:36.68,0:13:40.20,Default,,0000,0000,0000,,(Applause)