听力文摘：如何挑选美味番茄（在线收听）

Most of us have had the same experience.

大多数人都有过这样的经历，

We see a big, red tomato in the grocery store, take it home for our salad, and find out that it tastes like cardboard.

从商店里挑选出又大又红的番茄回去做沙拉，然后一尝，味同嚼蜡。

You might think that the tomato is sub-par because it's been picked before it ripened, or shipped across the country.

你可能认为买回的番茄味道不好是因为它没有成熟就被摘下，或者是运输过久的原因。

Those things can be true, but scientists have found another reason why modern tomatoes have little or no taste.

这的确是一部分原因，然而科学家们发现现今的番茄不好吃还有其它原因，

It's in their genes.

那就是它们的基因问题。

The problem began with old fashioned or heirloom tomatoes.

这个问题要追溯到从前的天然番茄，

They didn't ripen consistently.

它们并不总能完全长熟，

Someareas would be red, while other areas, usually near the stem, would be white or green.

番茄的有些部分是红的，而其它地方，尤其是靠近茎蒂的地方，往往是白色或绿色的。

About seventy years ago, tomato breeders accidentally discovered a variety that turned red uniformly.

大约70年以前，番茄种植者们偶然间发现一种全红的番茄品种，

Consumers liked the way the tomatoes looked, and companies that made ketchup and tomato sauce could make better looking products.

不仅消费者们喜欢这种模样的番茄，番茄酱制造公司也能生产出卖相更好的产品，

The trouble was, red did not equal tasty.

然而问题也出现了，看起来好看并不代表它的口感好。

While experimenting with weed genes that turned tomatoes dark green, geneticists accidentally discovered one of the reasons why today's tomatoes lack taste.

基因学家在对使番茄呈墨绿色的基因进行实验的过程中，意外发现了现今西红柿乏味的另外一大原因。

Modern tomatoes are light green before they turn uniformly red.

现在的西红柿在全部变红之前是呈浅绿色的，

Surprisingly, the mutation that gives tomatoes uniform red color actually disables some of the ripening genes.

令人惊奇的是，让番茄变红的变异却恰恰抑制了成熟基因的作用。

Those genes allow the fruit to make its own sugar which makes the tomato sweeter.

而成熟基因可以使水果产生糖分，从而使番茄变甜，

The genes also increase the amount of carotenoid pigments,which give tomatoes the red color.

同时产生更多的类胡萝卜素，使番茄变红。

When researchers turned the ripening genes back on, their experimental tomatoes had twenty percent more sugar and up to thirty percent more carotenoids.

当研究者们尝试着将成熟基因恢复到原有数量后，他们的实验番茄中所含的糖分增加了20%，类胡萝卜素提高了30%。

Unfortunately, regulations prohibited researchers from tasting their experimental fruits, but youcan try eating heirloom tomatoes.

遗憾的是，由于法规的原因，研究者们无法品尝自己的实验番茄，不过你们可以试着尝尝那些纯天然的番茄。

They aren't as pretty looking, but are tastier.

它们不中看，但是很好吃。