Dr. Andy

Reflections on medicine and biology among other things

Wednesday, March 23, 2005

"It's Just Weird"

I'll say. Apparently, plants have a reservoir of genetic material, from which they can correct mutations in their DNA.

In a discovery that has flabbergasted geneticists, researchers have shown that plants can overwrite the genetic code they inherit from their parents, and revert to that of their grandparents.

I didn't believe it either, but it sounds like it may be true (I don't have access to the full article here at home, I'll read it when I go to work and update later).

The researchers, at Purdue, were studying Arabidopsis, the most commonly used organism in plant genetics. Having identified a gene, HOTHEAD, that caused abnormal fusion of flower petals, they noticed that about 10% of offspring of HOTHEAD flowersdeficienct plants had normal flowers. They went back and showed that the gene sequences had reverted to normal.

One obvious possibility would be contamination, but presumably they were very careful about that. Excluding that, the gene correction implies a normal template somewhere in the organism. They couldn't find a DNA copy, so they speculate that there is an RNA reservoir somewhere in the cell. This seems plausible, but presumably you could check for such a copy by doing RT-PCR (basically using an enzyme that converts RNA to DNA and then amplifying via PCR) on a mutant plant. Some fraction of the amplified RNA should code for the correct gene.

One thing I'll be interested to see is how much of the gene is corrected and how well the "RNA copy" matches the original DNA.

This would be an incredible finding, if verified. Think of all the questions it raises. Where is the "gene reservoir" kept? How is RNA deposited in it? When is it activated?

I'll count myself as skeptical, but open minded


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