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Startling Scientists, Plant Fixes Its Flawed Gene (NICHOLAS WADE, 3/23/05, NY Times)

In a startling discovery, geneticists at Purdue University say they have found plants that possess a corrected version of a defective gene inherited from both their parents, as if some handy backup copy with the right version had been made in the grandparents' generation or earlier.

The finding implies that some organisms may contain a cryptic backup copy of their genome that bypasses the usual mechanisms of heredity. If confirmed, it would represent an unprecedented exception to the laws of inheritance discovered by Gregor Mendel in the 19th century. Equally surprising, the cryptic genome appears not to be made of DNA, the standard hereditary material.

The discovery also raises interesting biological questions - including whether it gets in the way of evolution, which depends on mutations changing an organism rather than being put right by a backup system.

It could certainly help explain the stubborn persistence of species.

MORE:
Plants Fix Genes With Copies From Ancestors (Rick Weiss, Washington Post, March 23, 2005)

Plants inherit secret stashes of genetic information from their long-dead ancestors and can use them to correct errors in their own genes -- a startling capacity for DNA editing and self-repair wholly unanticipated by modern genetics, researchers said yesterday.

The newly discovered phenomenon, which resembles the caching of early versions of a computer document for viewing later, allows plants to archive copies of genes from generations ago, long assumed to be lost forever.

Then, in a move akin to choosing their parents, plants can apparently retrieve selected bits of code from that archive and use them to overwrite the genes they have inherited directly. The process could offer survival advantages to plants suddenly burdened with new mutations or facing environmental threats for which the older genes were better adapted. [...]

Pruitt said others have occasionally noted the appearance of "revertant" plants but ignored them, assuming they were the result of sloppy technique or other errors. By contrast, Pruitt and Lolle took the observation seriously, said Elliot Meyerowitz, a pioneering arabidopsis researcher at California Institute of Technology.

"There are different sorts of scientists. Some like to ignore the exceptions, and others like to concentrate on them," Meyerowitz said, adding that he suspects the novel gene-fixing mechanism is present in a wide variety of organisms, including animals. He suspects the trick has been overlooked because it operates only some of the time and because scientists have been predisposed to write off the evidence as random events.

Posted by Orrin Judd at March 23, 2005 12:00 PM