Mutation method for plants `will benefit humans'

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SCIENTISTS HAVE discovered a new way of creating genetically modified plants which promises to produce dramatically different forms of flowers, fruit and vegetables.

The researchers have identified the key genetic mechanism used by all flowering plants - from cabbages to tulips - that controls the development of everything above the roots. It means it will be possible to engineer the genetics of plants at a more fundamental level than is possible now, creating the potential to develop more intricate flower heads, larger fruits and shorter stalks.

Elliot Meyerowitz, professor of biology at the California Institute of Technology (Caltech), said his team has located three genes that determine how cells divide within the vital part of a plant called the apical meristem, which is where new plant tissue is generated. Botanists liken the meristems of plants to the "stem cells" of animals, which are the mother cells from which all other cells in the body are derived.

"[Meristem cells] divide in highly specific patterns to make leaves and stems and flowers. Everything you see above ground arises from these cells," said Professor Meyerowitz.

The genes identified by the team, and published in the journal Science, control the communication network used by plants to make tissues, enabling the scientists to tinker with the basic plan by which a plant is destined to grow.

When the scientists eliminated the genes from an Arabidopsis weed, which normally grows six inches high with a thin, fragile stem and a few white flowers on the end, the plant grew a much thicker stem and mutant flowers with extra reproductive organs.

"This means the researchers are in control of the genetic mechanism that governs various characteristics of a plant. Since the effect is genetic, the mutated characteristics are passed along to future generations," said a spokesman for Caltech.

Professor Meyerowitz said the discovery could be used to mutate certain plants, of benefit to humans, to create ones with more favourable traits. "The difference between a cherry tomato and a big beefsteak tomato is just like the difference between a normal Arabidopsis plant and those that are mutant [for these genes]," Professor Meyerowitz said. "So there are ways to make fruit bigger without understanding the process. But what we're trying to do is understand the process."