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.
我相信要培育出極耐旱作物, 為世界糧食安全提供 一定程度的解決之道, 秘密在於復甦植物, 這張圖片顯示它們處在 嚴重乾旱下的狀態。 你們可能會認為 這些植物看起來已經死了, 但並非如此。 給它們水, 它們會在 12 到 48 小時內 復甦、變綠、開始成長。
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.
為什麼我會說 培育耐旱作物 可以提供糧食安全? 目前全世界約有 70 億人口。 據估計到了 2050 年, 我們會有 90 到 100 億人口, 大部分的增長會在非洲。
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.
世界糧食與農業組織提出, 依目前的耕作方式, 我們需要 70% 的成長 以滿足此需求。 有鑑於植物位於食物鏈的底層, 此增長必須由植物提供。
That percentage of 70 percent does not take into consideration the potential effects of climate change.
70 % 這樣的百分比數字, 還沒有考慮到 氣候變遷的潛在影響。
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.
這是截自戴研究員 於 2011 年出版的研究報告, 他考慮到 所有氣候變遷的潛在影響, 並陳述,除了其它影響, 因為缺雨或不常下雨, 乾旱情況會加重。 這裡看到的紅色區域 是直到最近 都很成功的農業用地, 但無法再使用,因為降雨不足。 圖上這種情況預計 將於 2050 年發生。 非洲大部分地區, 事實上全球大部分區域, 都會有麻煩。 我們不得不想一些 非常高明的方式來生產糧食。 最好是選耐旱作物。
The other thing to remember about Africa is that most of their agriculture is rainfed.
非洲有另一件事要記得, 絕大部分的農業都是 看天田(雨養農業)。
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.
在這個世界培育 耐旱作物並不容易。 原因是水。 水是地球生命的要素。 所有活著、還在代謝的生物, 舉凡微生物或你我, 主要都由水組成。 所有的生命反應都在水中發生。 失去一小部分的水 就會導致死亡。 你和我有 65% 是水, 只要失去 1% 的水就會死亡。 但是我們能改變行為 以避免這種情況。 植物不能。 它們牢牢釘在地上。 所以首先它們比我們 多含一點水, 大約 95% 都是水, 可以比我們多失去一點水分, 從 10% 到約 70% 都可以, 端看是哪種植物, 但是只能短暫失水。
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.
大部分植物都會想辦法 抗拒或避免失水。 植物抗拒失水最極端的例子 就是多肉植物。 它們通常很小、很漂亮, 但是它們為了保住水分, 付出了極大的代價, 就是長得奇慢無比。 可以在樹木或灌木中 找到避免失水的例子。 它們札下深根 , 佈下地網尋找水源, 隨時補注自己, 保持含水狀態。
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.
右邊這種樹 叫波巴布樹(猢猻樹)。 又稱為倒栽樹, 就是因為根與莖的比例 差別如此之大, 看起來很像倒著種的樹。 當然它的根部 必需讓整棵樹含水。
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.
大概最常見的避免失水策略 可在一年生植物中看到。 一年生植物 佔糧食供給的一大部分。 我國西海岸, 一年大部分的時間 都看不到什麼植物生長。 但是春天一下雨, 你就看到這個: 開花的沙漠。
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, 是只在雨季成長。 到了季末它們會結種子, 種子是乾的, 8% 到 10% 的水, 但是的確是活的。 那麼乾卻還活著的東西, 我們就稱為耐旱。
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.
在乾燥狀態時, 種子能做的就是 靜躺在極端環境下 很長一段時間。 下次雨季來時, 就發芽成長, 生命週期周而復始。
It's widely believed that the evolution of desiccation-tolerant seeds allowed the colonization and the radiation of flowering plants, or angiosperms, onto land.
大家普遍認為 種子的耐旱性演化 可以使開花植物 或被子植物,能在陸地上拓殖、輻射。
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.
再來談一年生植物 如何成為最主要的糧食來源。 小麥、稻米及玉米 佔植物糧食供應量的 95%。 這是很好的策略, 因為你可以在短時間內 生產大量的種子。 種子富含能量, 所以能提供很多卡路里, 你可以儲糧以備飢荒, 但是有個缺點。 一年生植物的營養組織, 根部及葉片, 沒有太多 抗受性、迴避性或耐受性的遺傳特質。 它們不需要這些特質。 它們在雨季生長, 然後結種子以幫助它們 撐過一年其餘的日子。
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.
所以儘管在農業界 大家一致努力 要改良作物的 抗受性、迴避性及耐受性, 尤其是抗受性及迴避性, 因為我們有很好的範本 瞭解這些如何作用, 我們仍然得到像圖上 這樣的結果。 非洲的玉米田 在兩星期無雨的情況下, 死亡殆盡。
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.
我們有一個解決方案: 復甦植物。 這種植物可以失去 細胞內 95% 的水分, 維持在乾燥、近似死亡 狀態下數月到數年, 然後給它們水分, 它們就會變綠,又開始成長。 這些就像種子一樣 可以耐旱。 這些就像種子一樣 可以禁得起極端環境條件。 這是非常罕見的現象。 只有 135 種開花植物 可以做到這點。
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.
我要給大家看一段影片, 是這三種植物的復甦過程, 按圖片上的順序播放。 影片下方有時間軸, 大家可以看到過程有多快。
(Applause)
(掌聲)
Pretty amazing, huh?
很驚人吧?
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.
我過去 21 年都在 試著瞭解它們如何辦到這一點。 這些植物如何能乾枯卻不死亡? 我研究很多種不同的復甦植物, 這裡看到的是含水及乾燥狀態, 有幾個原因。
One of them is that each of these plants serves as a model for a crop that I'd like to make drought-tolerant.
其中一個是這裡的 每種植物都充作研究範本, 以研究我想培育的耐旱作物。
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.
舉個例子,左上方是一種草, 畫眉草屬植物, 它有個近親叫 衣索比亞畫眉草, 很多人叫它苔麩, 這是衣索比亞國民食物, 無麩質, 我們想讓它耐旱。
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?
另一個原因要看各種植物, 就是,至少起初是這樣, 我想知道:是不是 每種植物都有同樣的反應? 是不是都用同一種機制 讓自己失水卻不至於死?
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.
所以我著手用我們稱為 系統生物學的方法, 以期對耐旱性能有完整的瞭解, 我們看所有的東西, 從分子到全株、 生理生態學階層都看。
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.
舉個例子,我們會看像是 植物在變乾的過程中, 在解剖學上經歷的變化 及其超微結構。 我們會看轉錄組, 這只是一個技術名詞, 基本上就是要看哪些基因 在因應乾燥過程中 會被開啟或關閉。 大部分的基因都製造蛋白質, 所以我們也看蛋白質組。 為了因應乾燥, 會製造出哪些蛋白質? 有些蛋白質是為了合成酵素, 產生代謝物, 所以我們也看代謝物組。
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.
這很重要, 因為植物牢牢釘在地上。 它們用我稱為 非常精準的化學兵工廠 來保護自己不受環境逆境影響。 所以去看死亡過程的 化學變化就很重要。
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.
我們最近的研究 在看分子層次, 我們看的是脂類組, 脂質如何變化以因應死亡。 這也很重要, 因為所有的生物膜 都由脂質組成。 它們能形成薄膜是因為在水中。 把水拿掉,薄膜就會解體。 脂質還作為打開基因的信號。
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.
然後我們用生理及生化研究 試著瞭解我們假設的 保護因子的功用, 這些因子是我們 在其它研究中發現的。 然後用所有研究結果 去試著瞭解 植物如何適應自然環境。
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.
我一直有套哲理, 就是我必須 對耐旱性機制有全盤瞭解, 才能對其生物應用 提出有意義的建議。
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.
我很確信有些人正在想: 「生物應用? 她是說她要培育基改作物?」 這個問題的答案是: 要看你怎麼定義基改。
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.
我們今天吃的作物, 小麥、稻米、玉米, 其基因都已改造成 與原來的老祖宗大不相同, 但是我們不認為這些是基改, 因為這些是傳統育種的產物, 如果你問,我是否要把 復甦作物的基因放進作物中, 答案是沒錯。
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.
時間就是成敗的關鍵, 我們已經試過這種方法。 更正確的說法是 我在開普敦大學的合作夥伴, 湯姆森和拉弗丁博士, 已經帶頭做這種方法, 我等一下就會 給大家看一些數據。
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.
但是我們即將用一項 非常有野心的方法, 我們的目標是打開一系列基因, 它們本來就存在於每種作物內。 只是在非常乾旱的情況下 這些基因從未被打開過。 我讓大家自己判斷 這該不該稱為基改。
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.
我現在就給大家看一下 第一次做的數據。 為了讓大家明白, 我必須解釋一下 基因如何運作。
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.
你們大概都知道 基因由雙股 DNA 組成。 DNA 緊密纏繞成染色體, 存在於你或植物體內的 每一個細胞中。 如果你把 DNA 解開, 就得到基因。 每個基因都有一個啟動子, 就像開關一樣, 還有基因編碼區, 及一個終止子, 表示這是該基因的終點, 下一個基因要開始。
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.
啟動子不像開關 那麼簡單。 它們通常需要很多微調, 很多條件必須存在且正確, 基因才會打開。 所以做生技研究時, 我們通常使用可誘導型啟動子, 我們知道如何開啟它。 我們將其與要研究的基因配對 並放入植物中, 看該植物如何反應。
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.
在我要跟大家談的這個研究中, 我的合作夥伴用一種 由乾旱誘發的啟動子, 我們在復甦植物中發現。 這個啟動子的好處是 我們不用管它。 植物本身會感覺到乾旱。 我們用這個啟動子驅動 復甦植物內的抗氧化基因。 為什麼是抗氧化基因? 因為所有的逆境, 尤其是乾旱, 都會產生自由基, 或活性氧類, 它們的破壞性極強, 且會導致作物死亡。 抗氧化基因會停止該破壞。
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.
現在看到的是某種玉米品系的數據, 這在非洲極常使用。 箭頭左邊的是 沒有該基因的植株, 右邊的 植株有抗氧化基因。 三星期不澆水後, 有該基因的植株 表現好的不得了。
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?
最後一點。 我的研究顯示 種子與復甦植物 耐旱性的機制相當相似。 所以我問這個問題, 這兩者都用同樣的基因嗎? 或用略為不同的問法, 復甦植物會利用 種子的耐旱性基因 在根部與植物上嗎? 它們會把這些種子基因的任務 在根部及葉片上利用嗎?
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.
我的答案是, 從我的研究小組, 及最近一起合作, 位於荷蘭的希和教授, 美國的奧利佛 法國的茱莉亞等 所得的結果, 我的答案是有, 的確有一組關鍵基因 與兩者都有關。
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.
我用這張圖跟大家粗略 說一下玉米的情況, 開關之下的染色體 代表耐旱基因。 玉米在種子發育 最後階段要乾掉時, 就會打開這些基因。 復甦植物在乾掉時 也會打開同樣的基因。 因此,所有現代作物 根部及葉片內都有這種基因, 只是從來不打開。 它們僅打開 種子組織內的這種基因。
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.
所以我們現在正在 瞭解環境與細胞信號 如何打開 復甦植物內的這些基因, 並在作物中模擬此過程。
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.
最後一點想法。 我們現在做的就是, 很快速地重現一千到四千萬年前 大自然復甦植物演化的過程。
My plants and I thank you for your attention.
我的植物和我 都感謝大家的關注。
(Applause)
(掌聲)