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First complete plant genome yields bountiful harvest of genes
Arabidopsis thaliana is sequenced by international collaboration
By Bijal P. Trivedi

Scientists from the United States, Europe and Japan announced this week the completion of the first plant genome sequence. The plant, Arabidopsis thaliana, is a tiny weed that has been dubbed the laboratory mouse of the plant world. It contains the basic set of genes required to create a flowering plant, and scientists believe they can use this information to improve the yield and nutritional content of crop plants and to identify genes that will lessen reliance on chemical pesticides and herbicides.

Seeing the entire genomic repertoire of Arabidopsis will help biologists understand how a plant is hard-wired, says Jeffrey Dangl, of the University of North Carolina, Chapel Hill. This plant does basically everything that crop plants do: it produces seeds, it flowers, it grows in salty soil, and it resists drought or cold. Knowing which genes allow it to thrive in different environments will help biologists find the equivalent genes in other types of plants. "If you want to study corn or wheat or rice, then you really should be studying Arabidopsis," says Dangl.

The Arabidopsis genome will also be useful for studying human genes and possibly for developing drugs. Researchers identified 139 genes that are also found in humans and are known to play roles in diseases ranging from colon cancer to cystic fibrosis to deafness to heart disease.

The genomic sequence of Arabidopsis contains 25,498 genes. But many of these are duplicates, and scientists estimate the number of unique genes at around 15,000—just slightly more than the fruit fly, Drosophila melanogaster.

The ultimate achievement, according to Dangl, is to understand the function of every Arabidopsis gene. This is the goal of "The Project 2010," which Dangl hopes the Arabidopsis research community will complete in the next decade. "Basically we want to create a virtual plant," says Dangl. "We want to be able to simulate exactly how different environmental conditions affect plant growth on a gene-by-gene basis. If the plant is attacked by pathogens like worms or mold we want to know exactly which genes get turned on." With this understanding, scientists may eventually be able to tailor plants to withstand a range of environmental stresses.

The Arabidopsis genome reports are in this week's issue of Nature. The journal Science describes "The 2010 Project" and features several reports that analyze the plant's genome.

Arabidopsis was chosen by plant geneticists because its short life cycle and small size make it an ideal experimental organism. About 1,000 plants can grow in the space of a standard notebook page. Arabidopsis also has a minimal, compact genome. The 125 million chemical units that make up the genome are organized into five chromosomes and the genes are located close together. Crop plants like wheat and corn have enormous genomes that are thousands of times larger than Arabidopsis, with entire chromosomes duplicated and genes that are scattered further apart.

See related GNN articles
»What makes plants grow?
»Clickable genomics: Plans for virtual plant posted

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The Arabidopsis Genome Initiative. Analysis of the genome sequence of the flowering plant Arabidopsis thaliana. Nature 408, 796-815 (December 14, 2000).

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