SSS 2011-08-02（在线收听） |
Plants are sitting ducks for every hungry herbivore that wanders past. But for some greens, a little grazing is the best thing that can happen. They grow back faster and fuller and make more seeds than they would have if left alone. Now scientists know how they do it—by stockpiling their DNA. The findings appear in the journal Ecology. Most animals have two full sets of chromosomes: one inherited from mom and one from dad. But plants don’t play by the same rules. Banana plants have three full sets; strawberries eight. And plants that get noshed on may take a similar tack.
Scientists took two strings of plants: one that comes back strong after grazing, another that wilts. And they found that the plants that bounce back after clipping boost their DNA content—some of their cells go from having 10 chromosomes to having 320.
The added DNA may allow the plants to rapidly make the proteins they need to grow and to produce seeds. And the size of the nucleus needed to contain all those chromosomes may make those cells bigger and bigger cells means a bigger plant. So chewed-on plants can fight back, and they are not afraid to go nuclear.
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin. |
| 原文地址：http://www.tingroom.com/lesson/sasss/2011/8/155323.html |