托福听力课外资料练习：科学美国人60秒无核水果科学研究相关内容分享

2017年07月31日14:42 来源：小站整理: 参与（0）阅读（3647）

摘要：托福听力的备考十分的重要，那么你应该如何练习呢?在备考过程中除了一些真题之外，一些常用的课外资料也是十分重要的。小编经常用到的就是科学美国人60秒，下面编在这里为为大家整理了科学美国人60秒：无核水果科学研究相关的内容分享，希望对大家有帮助。

在托福听力考试的备考过程中，科学美国人60秒相信大家一定用得比较多，那么大家平时是如何利用这个课外资料的呢?这里小编整理了科学美国人60秒无核水果科学研究的内容分享，大家一起来学习一下吧。

科学美国人60秒听力练习：无核水果科学研究

科学美国人60秒英文文本

Mark Twain called it “the most delicious fruit known to men.” He was talking about the cherimoya. If you never heard of it, there’s good reason. It has a feature that has prevented it from becoming widely popular—numerous big seeds fill its sweet white flesh.

But now scientists in Spain and at the University of California, Davis, have found the key to making the cherimoya and related fruits seedless. They published their research in the Proceedings of the National Academy of Sciences. [Jorge Lora et al., "Seedless fruits and the disruption of a conserved genetic pathway in angiosperm ovule development"]

It’s generally tough to develop a seedless fruit—bananas and oranges are rare successes. Breeding for seedlessness usually fails to produce the fully developed fruit consumers demand. But the scientists found a spontaneous mutation that causes seedlessness in a cherimoya relative, the sugar apple. They compared its genome to that of a seedless mutant of a plant called Arabidopsis that’s used in a lot of research.

In both cases, they found a deletion of one particular gene. The researchers say this is the first time a gene for seedlessness has been determined. If they can find a way to knock out that gene in the cherimoya, it could bring Mark Twain’s favorite fruit, and many others, to a grocery store near you.

—Cynthia Graber