passage2

A second attempt at domesticating the tomato

第二次尝试栽培番茄

A It took at least 3,000 years for humans to learn how to domesticate the wild tomato and cultivate it for food. Now two separate teams in Brazil and China have done it all over again in less than three years. And they have done it better in some ways, as the re-domesticated tomatoes are more nutritious than the ones we eat at present.

人类花了至少三千年才学会了如何培育野生番茄，把它栽培种植成食物。如今巴西和中国的两支独立团队在不到三年的时间里又重新来了一轮。而且他们在某些方面做得更胜一筹，因为这些改造栽培出来的番茄比我们目前在吃的那些更有营养。

This approach relies on the revolutionary CRISPR genome editing technique, in which changes are deliberately made to the DNA of a living cell, allowing genetic material to be added, removed or altered. The technique could not only improve existing crops, but could also be used to turn thousands of wild plants into useful and appealing foods. In fact, a third team in the US has already begun to do this with a relative of the tomato called the groundcherry.

这种做法仰赖于具有革新意义的CRISPR基因组编辑技术，可以对一个活体细胞的DNA进行刻意的改造，以此增加、去除或修改基因物质。这一技术不但能改良现有的作物，而且还可用来将数以千计的野生植物种类变成有益且美味的食物。实际上，第三支来自美国的团队已经开始在一种叫做“地櫻桃”的番茄属植物上进行这种尝试了。

This fast-track domestication could help make the world’s food supply healthier and far more resistant to diseases, such as the rust fungus devastating wheat crops.

这种快车道栽培方式有助于全球食物供应变得更健康，作物对疾病的抵抗力也会大大增强，例如抵抗会大规模破坏小麦作物的锈病菌。

‘This could transform what we eat,’ says Jorg Kudla at the University of Munster in Germany, a member of the Brazilian team. ‘There are 50,000 edible plants in the world, but 90 percent of our energy comes from just 15 crops.’“

这有可能会彻底改变我们吃什么，”巴西团队中的一名成员、来自德国明斯特大学的Jorg Kudla如是说。“世界上一共有50,000种可食用植物，但是我们所获取能量的90％都来自于区区15种作物。”

‘We can now mimic the known domestication course of major crops like rice, maize, sorghum or others,’ says Caixia Gao of the Chinese Academy of Sciences in Beijing. ‘Then we might try to domesticate plants that have never been domesticated.’“

我们现在可以模拟主要粮食作物如水稻、玉米、高粱等的已知栽培过程，”北京中科院的Gao Caixia这样说。“接下来我们也许可以试着去栽培一些此前从未被人工培植过的植物。”

B Wild tomatoes, which are native to the Andes region in South America, produce pea-sized fruits. Over many generations, peoples such as the Aztecs and Incas transformed the plant by selecting and breeding plants with mutations* in their genetic structure, which resulted in desirable traits such as larger fruit.

野生番茄原产于南美的安第斯地区，结出的是豌豆大小的果实。世世代代的阿兹台克人和印加人等民族通过选择和培育那些基因结构中发生了突变、从而具备更大果实等优良特性的番茄品种，改造了这种植物。

But every time a single plant with a mutation is taken from a larger population for breeding, much genetic diversity is lost. And sometimes the desirable mutations come with less desirable traits. For instance, the tomato strains grown for supermarkets have lost much of their flavour.

但是每当某一种发生了突变的植物从更大的属种中挑出来被单独培育之时，就会丢失很多基因多样性。并且，有时候这种优良的突变还会随之带来一些不那么令人喜爱的特质。例如，供超市售卖的番茄品类就已经丧失了大部分的西红柿味。

By comparing the genomes of modern plants to those of their wild relatives, biologists have been working out what genetic changes occurred as plants were domesticated. The teams in Brazil and China have now used this knowledge to reintroduce these changes from scratch while maintaining or even enhancing the desirable traits of wild strains.

通过将现代植物及其野生近缘种的基因组进行对比，生物学家们已经逐渐破译出当植物被人工栽培时会出现哪些基因变化。巴西和中国的团队目前已经运用这一知识在野生植物品种身上从零开始重新诱发这些改变，同时保留甚至加强一些人类想要的特性。

C Kudla’s team made six changes altogether. For instance, they tripled the size of fruit by editing a gene called FRUIT WEIGHT, and increased the number of tomatoes per truss by editing another called MULTIFLORA.

库德拉的团队一共做了六项更改。例如，他们通过编辑一项称为“果重”的基因使得果实的大小长到了原先的三倍，还通过编辑另一项称为“多花”的基因增加了每秧架结果的数量。

While the historical domestication of tomatoes reduced levels of the red pigment lycopene – thought to have potential health benefits – the team in Brazil managed to boost it instead. The wild tomato has twice as much lycopene as cultivated ones; the newly domesticated one has five times as much.

历史上对番茄的人工栽培减少了其中所含有的红色素“番茄烃”——它被认为可能有益身体健康——而巴西团队却设法提高了其含量。野生番茄所含有的番茄烃是人工养殖番茄的两倍；新栽培出来的品种则含有五倍。

‘They are quite tasty,’ says Kudla. ‘A little bit strong. And very aromatic.’“

它们的味道很好，”库德拉说。“口味稍有点重。闻起来香气四溢。”

The team in China re-domesticated several strains of wild tomatoes with desirable traits lost in domesticated tomatoes. In this way they managed to create a strain resistant to a common disease called bacterial spot race, which can devastate yields. They also created another strain that is more salt tolerant – and has higher levels of vitamin C.

中国团队重新培育出了几种野生番茄品种，这些番茄有着人王培植番茄身上已经消失了的一些优点。通过这种方式，他们培育出的一种番茄可以抵抗一种称为“疮痂病”的常见病，这种病菌具有摧毁番茄产量的威力。他们还培育出了另外一个更加耐盐的番茄品种——而且维生素C的含量更高。

D Meanwhile, Joyce Van Eck at the Boyce Thompson Institute in New York state decided to use the same approach to domesticate the groundcherry or goldenberry (Physalis pruinosa) for the first time. This fruit looks similar to the closely related Cape gooseberry (Physalis peruviana).

与此同时，纽约州博伊斯汤普森研究所的Joyce Van Eck决定使用同样的方法对地樱桃或称黄金莓（Physalis pruinosa）进行这项前无古人的栽培尝试。这种水果的外观类似于其近亲品种海角鹅莓（Physalis peruviana）。

Groundcherries are already sold to a limited extent in the US but they are hard to produce because the plant has a sprawling growth habit and the small fruits fall off the branches when ripe. Van Eck’s team has edited the plants to increase fruit size, make their growth more compact and to stop fruits dropping. ‘There’s potential for this to be a commercial crop,’ says Van Eck. But she adds that taking the work further would be expensive because of the need to pay for a licence for the CRISPR technology and get regulatory approval.

地樱桃在美国其实已经在限量售卖中，但是它们的生产很困难，因为这种植物惯于四处蔓延生长，小小的果实只要一成熟就会从枝头掉落。Van Eck的团队从基因上编辑了这些植物以增大果实尺寸，使它们生长得更加紧凑并防止果实脱落。“它有成为一种经济作物的可能性。”Van Eck如是说。但是她也补充说，要将这项工作深入推进下去会耗资颇巨，因为需要为使用CRISPR技术的特许证付费并经过注册审批。

E This approach could boost the use of many obscure plants, says Jonathan Jones of the Sainsbury Lab in the UK. But it will be hard for new foods to grow so popular with farmers and consumers that they become new staple crops, he thinks.

这个方法可以促进对许多鲜为人知的植物的使用，英国塞恩斯伯里实验室的Jonathan Jones 这样说。然而这些新型食物若是想在农夫和消费者那里受欢迎到成为新的主要农作物则会很难，他这样认为。

The three teams already have their eye on other plants that could be ‘catapulted into the mainstream’, including foxtail, oat-grass and cowpea. By choosing wild plants that are drought or heat tolerant, says Gao, we could create crops that will thrive even as the planet warms.

这三支团队已经将目光投向了其他有可能“一跃成为主流”的植物，包括狐尾草、燕麦草和豇豆。通过选择那些耐旱或耐高温的野生植物，我们就能培植出即使全球变暖也能繁荣生长的作物，Gao这样说道。

But Kudla didn’t want to reveal which species were in his team’s sights, because CRISPR has made the process so easy. ‘Any one with the right skills could go to their lab and do this.’

但是Kudla并不想透露他的团队目前正在钻研哪些植物品种，因为CRISPR技术使得这个过程变得轻而易举。“任何人有了恰当的技术都可以进入自己的实验室去做这件事。”

* mutations: changes in an organism’s genetic structure that can be passed down to later generations

突变：生物体遗传结构中可以遗传给后代的变化