A部分

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.

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.

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.

‘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.’

‘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.’

B部分

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.

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.

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.

C部分

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.

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.

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

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.

D部分

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 () for the first time. This fruit looks similar to the closely related Cape gooseberry ().

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.

E部分

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.

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.

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.’

    A部分：

人类花费了至少3000年的时间来学习如何驯化野生番茄并栽培其作为食物。现在巴西和中国的两个独立团队在不到三年的时间内再次成功实现了这一目标。在某些方面，他们的成果更胜一筹，因为重新驯化后的番茄比我们现在吃的番茄更加有营养。

这种方法依赖于革命性的CRISPR基因组编辑技术，通过该技术可以有意地改变生物细胞的DNA，添加、删除或改变基因物质。这种技术不仅可以改善现有的作物，还可以将成千上万种野生植物转化为有用且吸引人的食物。事实上，美国的第三个团队已经开始利用与番茄相近的一种叫做接骨木樱桃的植物进行这样的实验。

这种快速的驯化方法有助于使全球食品供应更加健康，并且更能抵抗疾病，例如对小麦作物造成灾害的锈菌。

德国明斯特大学的约格·库德拉说：“这可能会改变我们的饮食方式。世界上有5万种可食用的植物，但我们90%的能量都来自15种作物。”

北京中国科学院的高彩霞说：“我们现在可以模拟水稻、玉米、高粱等主要作物的已知驯化过程。然后我们可以尝试驯化那些从未被驯化过的植物。”

B部分：

野生番茄原产于南美洲的安第斯地区，结出的果实只有豌豆大小。经过许多代人的努力，例如阿兹台克人和印加人等根据这些植物的遗传结构中的突变情况，选择和交配那些具有理想特征（如更大的果实）的植物，逐渐改变了这种植物。

但是，每次从较大的植物群体中选择一株突变的植物进行种植，都会导致大量的基因多样性丧失。有时，理想的突变也可能带来不太理想的特征。例如，供超市销售的番茄品种已经失去了大部分的风味。

通过比较现代植物与它们野生亲属的基因组，生物学家已经开始研究在植物驯化过程中发生的遗传变化。巴西和中国的团队现在利用这些知识，从头开始重新引入这些变化，同时保持甚至增强了野生品种的理想特征。

C部分：

库德拉的团队一共进行了六项改变。例如，通过编辑一个名为FRUIT WEIGHT的基因，他们使果实的大小增加了两倍；通过编辑另一个名为MULTIFLORA的基因，他们增加了每个花序的番茄数量。

尽管历史上对番茄的驯化减少了红色色素番茄红素（被认为具有潜在的健康益处），但巴西的团队成功地增加了番茄红素的含量。野生番茄的番茄红素含量是栽培番茄的两倍，新驯化的番茄红素含量是栽培番茄的五倍。

库德拉说：“它们非常美味，有点浓郁并且香味浓郁。”

中国的团队重新驯化了几个野生番茄品种，这些品种在栽培番茄中失去了一些理想特征。他们成功地培育出一种抗击普遍病害——细菌性斑病的品种，该病害可以导致产量大幅下降。他们还培育出一种耐盐性更强、维生素C含量更高的品种。

D部分：

与此同时，纽约州博伊斯-汤普森研究所的乔伊斯·范·艾克决定首次使用相同的方法来驯化接骨木樱桃或番莓。这篇文章来自拉科考亚网站。这种水果看起来与非常相似。

接骨木樱桃在美国已有限度地销售，但它们很难生产，因为这种植物的生长习性杂乱，并且小果实会在成熟时从枝条上掉落。范·艾克的团队通过编辑植物基因使果实更大、生长更紧凑，并防止果实掉落。范·艾克说：“这可能成为一种商业作物，但进一步研究需要支付CRISPR技术的许可费用并获得监管部门的批准，这样会很昂贵。”

E部分：

英国赛伯利实验室的乔纳森·琼斯表示，这种方法可以促进许多不知名植物的利用。但他认为，让新食品在农民和消费者中变得如此受欢迎，以至于它们成为新的主要作物将是困难的。

这三个团队已经注意到其他一些可能会“引爆主流市场”的植物，包括米草、稗草和豇豆。高彩霞说，通过选择耐旱或耐热的野生植物，我们可以创造出即使在地球变暖的情况下也能茁壮成长的作物。

但库德拉不愿透露他的团队正在研究哪些植物物种，因为CRISPR技术使这个过程变得如此简单。“任何具备正确技能的人都可以去他们的实验室做这项工作。”