Tuesday, March 22, 2005
Biotech - Purdue researchers find plants can fix bad genes
"Startling Scientists, Plant Fixes Its Flawed Gene" is the headline to this story today in the NY Times. The lead:
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 LA Times has a story headlined "Plants Can Fix Bad Genes, Study Shows." The lead:
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. * * *
The result, reported online yesterday in the journal Nature by Dr. Robert E. Pruitt, Dr. Susan J. Lolle and colleagues at Purdue, has been found in a single species, the mustardlike plant called arabidopsis that is the standard laboratory organism of plant geneticists. But there are hints that the same mechanism may occur in people, according to a commentary by Dr. Detlef Weigel of the Max-Planck Institute for Developmental Biology in Tübingen, Germany. Dr. Weigel describes the Purdue work as "a spectacular discovery."
The finding grew out of a research project started three years ago in which Dr. Pruitt and Dr. Lolle were trying to understand the genes that control the plant's outer skin, or cuticle. As part of the project, they were studying plants with a mutated gene that made the plant's petals and other floral organs clump together. Because each of the plant's two copies of the gene were in mutated form, they had virtually no chance of having normal offspring.
But up to 10 percent of the plants' offspring kept reverting to normal. Various rare events can make this happen, but none involve altering the actual sequence of DNA units in the gene. Yet when the researchers analyzed the mutated gene, known as hothead, they found it had changed, with the mutated DNA units being changed back to normal form. "That was the moment when it was a complete shock," Dr. Pruitt said.
Upending prevailing genetic theory, a team of scientists at Purdue University has discovered a mechanism in plants that allows them to correct defective genes from their parents by tapping into an ancestral data bank of healthy genetic material.The Washington Post story is headlined: "Plants Fix Genes With Copies From Ancestors." The lead:
In essence, the plants back up the evolutionary path and use past genes to restore traits that would otherwise be lost, according to a study published Tuesday in the online version of the journal Nature.
The finding proposes "an extraordinary view of inheritance," the scientists said in their paper.
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.Here is the Nature news release. The article itself is unfortunately subscription only.
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. * * *
"We think this demonstrates that there's this parallel path of inheritance that we've overlooked for 100 years, and that's pretty cool," said Robert E. Pruitt, a professor of botany and plant pathology at Purdue University in West Lafayette, Ind., who oversaw the studies with co-worker Susan Lolle.
The finding represents a "spectacular discovery," wrote German molecular biologists Detlef Weigel and Gerd Jurgens in a commentary accompanying the research in tomorrow's issue of the journal Nature, released yesterday. The existence of an unorthodox inheritance system does not overturn the basic rules of genetics worked out by Austrian monk Gregor Mendel in the 1800s, they noted. But like a newly discovered room in a mansion of treasures, it opens up a mind-boggling world of possibilities and proves that genetics is still a young science.