英語時(shí)差：大小形狀不一的番茄

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https://online2.tingclass.net/lesson/shi0529/10000/10183/261.mp3

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Don: It's a tomato I found! Don't you think it looks like Richard Nixon? I wonder why tomatoes and other fruits sometimes grow into such different shapes.

Y: Scientists wonder about that too, and they are a step closer to solving the mystery now.

D: Really? Why?

Y: As you already noticed, some fruits can grow in a wide variety of shapes and sizes. Wild tomatoes, for instance, are very small and round, but through selective breeding we now have cultivated tomatoes that may be pear-shaped, egg-shaped, or even donut-shaped.

Little was known about the mechanisms behind shape diversity, however, until scientists studied a gene called SUN. They chose to study the SUN gene because they noticed it was common in tomato varieties with elongated shapes.

The team isolated the specific part of tomato DNA that contained the SUN gene from normal and elongated tomatoes.

To test if the SUN gene were responsible for the elongated shape, the team inserted active copies of the SUN gene into the DNA of wild tomato plants.

D: The plants with small, round fruits?

Y: Exactly. When the SUN gene was inserted and "turned on" in wild tomatoes, the plants produced very elongated fruits instead of round ones! Then the scientists inactivated the SUN gene in the transformed wild tomato plants. With the gene switched off, the plants produced round small fruits again.

D: Is the SUN gene found in other plants? Because... I also found this pepper that looks like you, Ya?l!

Y: Thanks, Don.

D: Since tomatoes and peppers are closely related, it will be interesting to see if and how the SUN gene functions in peppers and other fruits.