Genetic Map of
a Plant Completed
Joseph B. Verrengia,
AP Science Writer
December 14, 2000; London, UK (AP) -- "From this point on, plant science will never be the same again and genetics will never be the same again," said Mike Bevan, European Coordinator of the $70 million international project. The plant project was started in 1996. Scientists selected Arabidopsis, a member of the mustard family and a cousin to cauliflower, over 250,000 other plant species because it is biologically simple and grows quickly -- as many as eight generations in a single year.
Arabidopsis has 25,498 genes on 5 chromosomes. The functions of two-thirds of its genes have been identified. Its genes contain about 0.117 GBP (billion chemical base pairs). By comparison, corn has 3.0 GBP, more than 30 times as much. Like animal models that have been genetically sequenced, it is easily manipulated in laboratory experiments and is widely used as a stand-in for more complex organisms.
"Arabidopsis now is the reference plant for all others," said Jeff Dangl, who studies plant diseases at the University of North Carolina. "It has all the genes that more complicated plants have for roots, seeds, flowers, and fighting diseases. Now we essentially know what it takes to make a flower."
Others said the sequencing was just the beginning of their work. A second phase seeks to identify all of the genes' functions by 2010. "Once we know what each gene does, we must figure out why that function is important," said Iowa State University corn geneticist Patrick Schnable. "We don't know how to do that yet." Arabidopsis genes already are being tested to make tailor-made crops that grow faster, withstand worsening climates, resist pests and disease, and provide vitamin boosts. Such designer crops would reduce the use of agricultural chemicals and, perhaps, save millions of acres of rainforest from the plow by boosting harvests on existing farms.
Opponents fear that tinkering with crop genes will result in unforeseen health and environmental consequences. Activist groups have blocked cargos of gene-modified grains from unloading in ports, and some consumers have refused to buy gene-modified products. Regulatory agencies in the United States and the European Union are considering stricter controls on both farmers and food processors.
The gene milestone has implications beyond the grocery store. As oil and gas prices rise, other labs are testing genes that would turn corn, soybeans, tobacco, and other crops into biological factories producing renewable supplies of fuels and industrial chemicals.
Less certain, but intriguing, is how the Arabidopsis genome might offer insights into the evolution of complex organisms and even help cure disease in humans. The sequence contains master genes controlling basic cell growth and behavior that have been at work since flowering plants appeared more than 125 million years ago.
The researchers found about 100 of the plant's genes that are closely related to human disease genes involved in deafness, blindness, and cancer. Investigating gene-based therapies initially will be easier -- and cheaper -- in the plant. Quite a legacy for a little weed, researchers said. "It's amazing that humans and plants share a number of genes," said Rod Wing, who is sequencing the rice genome at Clemson University. "It provides further evidence that we do have a common origin. Having the whole genome of this plant opens so many questions about evolution, like how related are we?"
Medical Writer Emma Ross in London and Science Writer Paul Recer in Washington contributed to this report.
Editor's Note: Collaborators on this project included Scripps Research Institute in La Jolla, CA; Salk Institute for Biological Studies in La Jolla, CA; USDA-UC Berkeley Plant Gene Expression Center in Albany, CA; the Stanford Genome Technology Center in Palo Alto, CA; UC Davis; CalTech in Pasadena, CA; the Carnegie Institution at Stanford University; Cereon Genomics LLC of Cambridge, MA and a subsidiary of Monsanto Co.; Mendel Biotechnology, Inc. of Hayward, CA; and Ceres, Inc. of Los Angeles, CA.