WASHINGTON - For the first time, scientists have deciphered the complete genetic code of a plant, providing new tools to produce sturdier, more nourishing plants and to protect them better from pests and disease.
Researchers say the DNA of a common weed known as arabidopsis - or thale-cress - will be a valuable supplement to the still-unfinished human genome project.
"Scientists now have a genetic road map to use in developing higher quality foods, new fibers, medicines and energy sources that will be needed in this new century," said Mary Clutter, assistant director of the National Science Foundation, which financed much of the work.
The map of arabidopsis DNA also could prove useful against human diseases, since some of its genes are similar to those involved in colon cancer, cystic fibrosis and other ailments.
"This new knowledge will be as important to humankind as the human genome sequence, because all, including the very poor, benefit directly from improvements in food supplies," said Caroline Dean, a researcher at the John Innes Centre in Norwich, England.
Rita Colwell, director of the National Science Foundation, called it "a revolution in our quest to improve plants for the benefit of society."
Despite the lofty hopes of the scientific community, the achievement may swell doubt and anger among those who are frightened by genetically modified plants and animals. Especially in Europe, tinkering with genes has raised widespread alarm and resistance.
But Colwell and Dean argued that detailed knowledge of the arabidopsis genome will help scientists accurately predict the effect of adding, removing or altering genes, thereby reducing the risk of unforeseen side effects.
More than 2,000 scientists from 30 countries took part in an international consortium that determined the sequence of most of the 125 million biological units, called bases, that make up the arabidopsis genome. Eleven articles on the humble weed were published in this week's editions of the American journal Science and its British counterpart, Nature.
A lowly cousin of cabbage, cauliflower and mustard, arabidopsis joins two small animals - a worm and a fly - as the only complex organisms whose DNA has been completely sequenced. A "working draft" covering 90 percent of the human genome was finished in June, but a final, accurate sequence of its 3 billion bases won't be ready until 2003.
"Most of the arabidopsis genes have counterparts in these animal species, indicating the common ancestry of plants and animals," Stanford University biologist Virginia Walbot wrote in Nature.
Scientists believe that plants and animals, including humans, descended from one-celled ancestors that went their separate ways about 1.6 billion years ago. Flowering plants, such as arabidopsis, appeared about 200 million years ago.
Researchers have been working on arabidopsis since the early 1970s, attracted by its small size - less than 8 inches tall - and rapid, six-week life cycle.
According to Clutter, research on arabidopsis has had a considerable impact on plant biology and agricultural biotechnology. It has helped scientists understand how plants sense and react to light, temperature and drought, and how they make useful chemicals.
Nearly 1,000 arabidopsis-related patents were issued even before its sequence was completed. Its genes have been used to make soybeans that produce more nutritious oils and better industrial lubricants. Work is progressing on genes that modify plants to clean up mercury, cadmium and other heavy metals. Other genes resistant to herbicides promise to permit agriculture without deep plowing, thus reducing soil erosion and saving energy.