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. 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.
我认为培育十分耐旱的农作物 某种程度上可以保障世界粮食安全 而其中的秘诀在于这张 拍摄于一个非常干旱的州的 图片中的复苏植物。 你也许认为这些植物看起来已经死了 但其实它们没死。 如果给它们水 它们将会在12-48小时后 复活,变绿,开始生长。
Now, 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.
现在,为什么我提议 培育耐旱的农作物 可以保障粮食安全呢? 当今世界人口大约为70亿 预计到2050年, 人口将增长至90-100亿, 这其中大部分的人口增长在非洲。
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. Given that plants are at the base of the food chain, most of that's going to have to come from plants.
世界粮农组织 建议我们在现有基础上 需要将农业产量 提高70% 来满足那时的需求。 因为植物是食物链的基础, 所以增加的产量大部分需要来自植物。
That percentage of 70 percent does not take into consideration the potential effects of climate change.
但是70%的增量 并没有考虑 气候变化所带来的潜在影响。
This is taken from a study by Dai 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 of rain or infrequent rain. 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 rainfall. 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.
这是戴在2011年 发表的研究报告, 里面他考虑了 气候变化带来的所有可能的影响 然后把它们展现出来 其中就有 由降水缺乏或频率低 所导致的干旱区域增加。 展示在这里的红色区域 是到目前为止 农业非常发达 但因为缺少降水 将来不能耕种的地区。 这是预计将在 2050年发生的状况。 非洲的大部分地区 实际上,全球的大部分地区 将会陷入困境。 我们将不得不想出一些 非常巧妙的方法来生产食物。 在其中比较合适的方法是 培育一些耐旱的作物
The other thing to remember about Africa is that most of their agriculture is rainfed.
关于非洲, 我们需要记住的另一件事是 他们的大部分农业主要靠雨水灌溉。
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. And 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.
现在,培育抗旱作物并非易事。 其中的原因在于水。 在这个星球上, 水是对于生命是必不可少的。 所有活着的、代谢旺盛的有机体, 从微生物到你我, 主要由水构成。 所有维持生命所需的反应发生在水中。 即使丧失少量的水也会导致死亡。 人体65%由水构成 如果我们其中 丧失1%的水,我们就会死。 但是我们可以通过行为的改变 来避免那种情况发生。 植物却不能。 它们生长在地上。 所以首先他们比我们含水量更多 大概95%是水分 它们也可以比我们多失去一些水 不同物种可以短时间内 损失10%到70% 的水分。
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, very 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.
大多数物种都会 抵制或尽量避免失水。 举一个抗失水者的极端例子:肉质植物 它们一般很小很漂亮 但是它们为了保持水分不得不 生长的十分缓慢。 避免失水的主要例子都是乔灌木 它们的根须深入地下 直至地下水资源 不停地吸取大量的地下水 来保持水分。
The one on the right is called a baobab. It's also called the upside-down tree, simply because the proportion of roots to shoots is so great that it looks like the tree has been planted upside down. And of course the roots are required for hydration of that plant.
右边的植物叫做猴面包树。 它也被人成为倒置的树 因为根部与地上部分 的比例实在是太夸张 以至于这棵树像是倒置的一样。 当然了为了保持水分 这样的根部是必须的。
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 of the year you don't see much vegetation growth. But come the spring rains, you get this: flowering of the desert.
也许一年生植物是 最常使用避免失水策略的植物了 一年生植物在我的国家的西海岸 是我们主要种植的食物来源 一年中的绝大部分时间 我们看不到这些蔬菜的生长 但当春天雨季来临,你可以看到 沙漠之中花开遍地。
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.
一年生植物的策略 就是只在雨季生长。 在雨季结束的时候 它们产生种子 种子很干燥, 只含有8%到10%的水 但却生机勃勃。 这样在干燥环境下仍保持活性的性质 叫做干燥耐受。
In the desiccated state, what seeds can do is lie in extremes of environment for prolonged periods of time. The next time the rainy season comes, they germinate and grow, and the whole cycle just starts again.
在干燥的国家 种子在如此极端环境下 可以存活很长的一段时间。 下次雨季来临时 它们马上发芽生长 如此循环往复。
It's widely believed that the evolution of desiccation-tolerant seeds allowed the colonization and the radiation of flowering plants, or angiosperms, onto land.
普遍认为正是进化出 这样干燥耐受的种子 才让开花植物和被子植物 在陆地上的定植和传播成为可能。
But back to annuals as our major form of food supplies. Wheat, rice and maize 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 there's a lot of food calories, you can store it in times of plenty for times of famine, but there's a downside. 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.
作为主要食物来源的一年生植物 比如构成我们食物来源95% 的小麦,水稻和玉米 看起来也是一个很好的策略 因为短时间内就可以生产大量的种子 种子富含可以被人体吸收的能量 所以你可以在食物充足的时候 为饥荒做准备。 但是也有不足之处。 这些植物的营养组织 根部和叶片 并没有什么 抵抗干燥,避免干燥 或者耐受干燥的特性 因为它们根本不需要。 它们本来就生长在雨季 而且已经生产了 可以度过余下时间的种子
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. Maize crop in Africa, two weeks without rain and it's dead.
而且无论农业专家如何努力 提升农作物的 抵抗、避免和耐受干旱的能力 尤其是抵抗和避免干旱的能力 尽管我们已经有了 很好的模型来了解植物的运作模式 我们仍然只得到了这样的结果。 非洲的玉米作物 经历两周不下雨之后 就死了。
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, these 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.
现在有一个方案 就是复苏植物。 这些植物可以失去95%的细胞水分 进入干燥的假死状态 长达数月之久 只要给它们水 它们马上就可以变绿开始生长。 像种子一样它们拥有干燥耐受性 可以忍受极端的环境。 这是非常罕见的现象。 全世界只有135种 开花植物可以做到。
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.
我将给各位放一段 三种复苏植物复苏过程 的视频。 在视频下方 有一个时间轴 各位可以看到一切发生得多么迅速。
(Applause)
(掌声)
Pretty amazing, huh?
很神奇 是吧?
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.
所以我用了21年时间 研究它们是如何做到的 这些植物如何做到干而不死? 因为很多原因我研究了 图中不同的复苏植物 在干燥和有水环境下 的状态
One of them is that each of these plants serves as a model for a crop that I'd like to make drought-tolerant.
其中一个原因是 每一种复苏植物 都可以作为一种 农作物的耐旱版本的模板
So on the extreme top left, for example, is a grass, it's called Eragrostis nindensis, it's got a close relative called Eragrostis tef -- a lot of you might know it as "teff" -- it's a staple food in Ethiopia, it's gluten-free, and it's something we would like to make drought-tolerant.
比如左上角这种草 叫做画眉虫草 它是苔麸的近亲 也就是很多人熟知的 埃塞俄比亚画眉草 那是埃塞俄比亚的主要作物 它不含谷蛋白 我们想开发耐旱版本的 埃塞俄比亚画眉草。
The other reason for looking at a number of plants, is that, at 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?
另一个我们研究其它各种各样的植物 的原因是, 至少我们希望从本质上了解 它们在做同样的事情么? 它们可以做到失水而不死 的内在机制是相同的么?
So I undertook what we call a systems biology approach in order to get a comprehensive understanding of desiccation tolerance, in which we look at everything from the molecular to the whole plant, ecophysiological level.
所以我采用系统生物学方法 希望对植物的耐旱性 有一个全面的了解 系统生物学方法就是 从分子层面 到整体植株生理生态层面的整体研究
For example we look at things like changes in the plant anatomy as they dried out and their ultrastructure. We look at the transcriptome, which is just a term for a technology in which we look at the genes that are switched on or off, in response to drying. Most genes will code for proteins, so we look at the proteome. What are the proteins made in response to drying? Some proteins would code for enzymes which make metabolites, so we look at the metabolome.
比如我们通过解剖 观察干枯的植物的变化 和它们的亚显微结构 我们观察转录组如何应对干旱 转录组是一个技术术语 意思是我们观察基因开关 在应对干旱时是开启还是关闭。 大部分基因会制造蛋白质 所以我们研究蛋白质组。 干旱来临时植物会制造什么蛋白质? 一些蛋白质会制造 让植物新陈代谢的酶 所以我们研究代谢组。
Now, this is important because plants are stuck in the ground. They use what I call a highly tuned chemical arsenal to protect themselves from all the stresses of their environment. So it's important that we look at the chemical changes involved in drying.
这很重要 因为植物都是固定在土地之上的 它们利用所谓的高度协调的化工厂 保护它们不受外界环境的压力。 所以研究这些 因为干燥引起的 化学变化也非常重要。
And at the last study that we do at the molecular level, we look at the lipidome -- the lipid changes in response to drying. And that's also important because all biological membranes are made of lipids. They're held as membranes because they're in water. Take away the water, those membranes fall apart. Lipids also act as signals to turn on genes.
最后我们在分子层面的研究中 我们研究了脂质体 脂质是如何变化的以应对干旱的。 这也很重要 因为所有的生物膜都是脂质的。 因为在水中所以它们保持膜状 脱离水后这些膜就会破碎。 脂质同样是开启基因的信号
Then we use physiological and biochemical studies to try and understand the function of the putative protectants that we've actually discovered in our other studies. And then use all of that to try and understand how the plant copes with its natural environment.
我们运用生理和生化研究方法 去试验和了解我们已经在 其他研究中发现的假定保护机制。 通过这些所有的研究来尝试理解 植物如何适应它周围的自然环境。
I've always had the philosophy that I needed a comprehensive understanding of the mechanisms of desiccation tolerance in order to make a meaningful suggestion for a biotic application.
我的科学哲学是 我需要对耐旱性的机制 有全面的理解才可以给出 对于生物应用的有意义的建议。
I'm sure some of you are thinking, "By biotic application, does she mean she's going to make genetically modified crops?" And the answer to that question is: depends on your definition of genetic modification.
我确信有一些人在想 “她所说的生物应用 是不是意味着转基因作物呢?” 这个问题的答案是: 取决于如何定义转基因。
All of the crops that we eat today, wheat, rice and maize, are highly genetically modified from their ancestors, but we don't consider them GM because they're being produced by conventional breeding. If you mean, am I going to put resurrection plant genes into crops, your answer is yes.
所有我们今天食用的作物 小麦,水稻和玉米 与祖先植株相比都是高度转基因的, 我们不认为它们是转基因作物 是因为它们一直 是用传统方式培育的。 如果你问我是不是打算把 复苏植物的基因植入作物中 我的回答是是的。
In the essence of time, we have tried that approach. More appropriately, some of my collaborators at UCT, Jennifer Thomson, Suhail Rafudeen, have spearheaded that approach and I'm going to show you some data soon.
时间紧迫 我们已经尝试了这些手段 准确地说 我的一些在UCT的同事 珍妮弗·汤姆森,萨尔·拉夫德恩 已经先行进行了实验 一会我将展示部分资料。
But we're about to embark upon an extremely ambitious approach, in which we aim to turn on whole suites of genes that are already present in every crop. They're just never turned on under extreme drought conditions. I leave it up to you to decide whether those should be called GM or not.
但是我们将要开展的 是一项极具野心的工作 我们的目标是启动 已经存在于每棵植株中的 整套基因 它们只是还没有 在极端干旱的环境下被激活 我希望各位可以自行判断 这种方式是否属于转基因。
I'm going to now just give you some of the data from that first approach. And in order to do that I have to explain a little bit about how genes work.
我将展示第一阶段实验的部分资料 在展示之前 我需要解释一下 基因工作的原理。
So you probably all know that genes are made of double-stranded DNA. It's wound very tightly into chromosomes that are present in every cell of your body or in a plant's body. If you unwind that DNA, you get genes. And each gene has a promoter, which is just an on-off switch, the gene coding region, and then a terminator, which indicates that this is the end of this gene, the next gene will start.
也许大家都知道 基因是DNA的双链结构。 它通过紧密的缠绕形成染色体 存在于每个人体或者植物的细胞之中 如果把DNA解缠 你就会得到基因 每一个基因有一个启动子 即是一个开关 基因转录区 和终止子 这意味着这一部分基因转录结束 下一个基因将要开始转录
Now, promoters are not simple on-off switches. They normally require a lot of fine-tuning, lots of things to be present and correct before that gene is switched on. So what's typically done in biotech studies is that we use an inducible promoter, we know how to switch it on. We couple that to genes of interest and put that into a plant and see how the plant responds.
启动子不是简单的开关 它们往往需要大量微调 在基因开关打开之前 要进行很多的瞄准和修正过程 所以基本上我们生物技术研究中 使用诱导型启动子 来研究如何打开启动子开关 我们把它植入我们感兴趣的基因 然后把基因植入植株 研究植株的反应。
In the study that I'm going to talk to you about, my collaborators used a drought-induced promoter, which we discovered in a resurrection plant. The nice thing about this promoter is that we do nothing. The plant itself senses drought. And we've used it to drive antioxidant genes from resurrection plants. Why antioxidant genes? Well, all stresses, particularly drought stress, results in the formation of free radicals, or reactive oxygen species, which are highly damaging and can cause crop death. What antioxidants do is stop that damage.
在我接下来展示的研究中 我的同事使用了在复苏植物中发现的 干旱诱导蛋白启动子。 这个启动子的优势在于不用外界手段 植物会自发感受干旱 我们使用启动子驱动 复苏植物的抗氧化剂基因 为什么是抗氧化剂基因? 所有的压力 尤其是干旱的压力 都会形成自由基 也就是活性氧。 活性氧极具破坏力 会直接导致植物死亡。 抗氧化剂可以阻止这种破坏。
So here's some data from a maize strain that's very popularly used in Africa. To the left of the arrow are plants without the genes, to the right -- plants with the antioxidant genes. After three weeks without watering, the ones with the genes do a hell of a lot better.
这是非洲常用的玉米品种 箭头左边的是没有这种基因的 右边的 是含有抗氧化基因的植株。 三周没有浇水之后 有抗氧化基因 的植株的状态要好得多。
Now to the final approach. My research has shown that there's considerable similarity in the mechanisms of desiccation tolerance in seeds and resurrection plants. So I ask the question, are they using the same genes? Or slightly differently phrased, are resurrection plants using genes evolved in seed desiccation tolerance in their roots and leaves? Have they retasked these seed genes in roots and leaves of resurrection plants?
在实验的最后 因为我的研究已经说明 种子和复苏植物的耐旱性的机制 有很多相似之处 我的问题是 他们是同一种基因么? 还是略有不同地被修饰过? 复苏植物是在根部和叶部上 也含有 这种耐旱基因么? 在复苏植物中 这些基因 又被根部和叶部重新使用了么?
And I answer that question, as a consequence of a lot of research from my group and recent collaborations from a group of Henk Hilhorst in the Netherlands, Mel Oliver in the United States and Julia Buitink in France. The answer is yes, that there is a core set of genes that are involved in both.
我可以回答这个问题 通过我和我的同事的小组的工作 通过来自荷兰的亨克·希尔霍斯特 来自美国的梅尔·奥利弗 和来自法国的朱莉娅布克 的一系列工作 我们认为答案是:是的。 它们都有一套完整的核心基因
And I'm going to illustrate this very crudely for maize, where the chromosomes below the off switch represent all the genes that are required for desiccation tolerance. So as maize seeds dried out at the end of their period of development, they switch these genes on. Resurrection plants switch on the same genes when they dry out. All modern crops, therefore, have these genes in their roots and leaves, they just never switch them on. They only switch them on in seed tissues.
我会大概以玉米为例解释一下 在开关下面的染色体里面有 耐旱性必要的全部基因 当玉米种子在它们发育的 最后一个阶段面临干燥环境时 开关就会打开。 复苏植物遇到干旱环境是也会 打开同样的开关。 因此所有现代的植物 都在它们的根部和叶部 拥有这些基因 只不过它们从来没有打开过开关。 它们只在作为种子时打开过开关。
So what we're trying to do right now is to understand the environmental and cellular signals that switch on these genes in resurrection plants, to mimic the process in crops.
我们现在尝试要做的 就是了解打开复苏植物基因开关的 环境信号和细胞信号 并在作物中模仿类似的过程。
And just a final thought. What we're trying to do very rapidly is to repeat what nature did in the evolution of resurrection plants some 10 to 40 million years ago.
最后我想说 我们只是在用飞快的速度重复 复苏植物在过去100万年到400万年 的大自然中进行的进化。
My plants and I thank you for your attention.
我和我的植物感谢您的关注。
(Applause)
(掌声)