Outwitting Mendel

Scientists have discovered that genetic inheritance is more complicated than they thought. Working on the model plant Arabidopsis, Robert Pruitt and his co-workers found that some of their mutant plants did not breed true when conventional genetics said they should. Worse than that, they seemed to be inheriting a gene that neither of their parents had, but their grandparents did!

Pruitt’s lab bred plants with mutations in the hothead gene, carrying one normal copy and one mutant copy. When these plants were bred, some of their offspring (as expected) carried two mutant copies of the gene and no normal copies. When these offspring were themselves bred together, the next generation was also expected to contain only the mutant copies of the gene, following the laws of inheritance that Gregor Mendel discovered over 100 years ago. However, about one-tenth of them had somehow gained a normal copy of this gene! Having ruled out contamination and any other conventional explanation, Pruitt’s team have concluded that the plants are somehow remembering what the normal gene should look like and that some offspring are reverting to that previous copy.

This makes evolutionary sense, because it would shield the plants’ descendents from the consequences of mutations (both beneficial and harmful) but has never previously been observed – possibly because such unexpectedly normal plants were discarded because they were thought to be contaminants! There is no evidence yet for how this might be happening, but suspicion lies with RNA, the companion molecule to the more familiar DNA.

pax et bonum

Article posted at 2:29pm on 29 March 2005
Category: Science, Struggling, General

“It was our view that it was heresy when we started working on it,...”

Excuse me? Did he really use the ‘h’ word? Surely not…

(Interesting. Struggled to resurrect my Mendelian genetics from 20-odd years ago, but I think I got there!)

Stephen (URL)
11:21pm on 29 March 2005