Wilson: Genetics teacher
By David Linzee
School of Medicine research- ers are part of a team that has generated the first complete DNA sequence of a plant. The team sequenced the genome of Arabidopsis thaliana, a flowering mustard.
Wilson: Genetics teacher |
Because Arabidopsis is a widely studied model organism, its sequence will enable scientists to study genes that control basic plant functions. This knowledge will be useful for improving important crops such as wheat, corn and soybeans. It also will aid the ongoing effort to identify genes in the human sequence.
The milestone is reported in the Dec. 14 issue of the journal Nature. The Arabidopsis Genome Initiative, an international consortium, performed the research. All data is available on the Internet (www.arabidopsis. org/home.html).
Under the direction of Richard K. Wilson, Ph.D., associate professor of genetics, the medical school's Genome Sequencing Center played a two-part role in the project. During the early stage, it constructed a genome map that was used by all the sequencing centers. In collaboration with Cold Spring Harbor Laboratory in New York and the John Innis Centre in the United Kingdom, it then sequenced chromosomes 4 and 5. Arabidopsis has five chromosomes.
Arabidopsis is a small plant that grows readily in the laboratory. Its unusually compact genome has just 125 million base pairs --the building blocks of the genome --ompared with wheat's 15 billion. Both plants have approximately the same number of genes --rabidopsis has 25,498, the researchers discovered --but wheat contains many more repeated sequences.
Information gained from the sequence may provide a basis for improving important crop plants through breeding or genetic engineering. Such improvements might include foods that last longer on supermarket shelves, are lower in fat or higher in protein or are tastier.
It also might help make crops hardier. Analysis of the sequence suggests that cell signaling pathways that respond to bacteria, parasites and other external threats are more abundant in plants than in other organisms. "Just as animals have immune systems, plants have ways of protecting themselves, too," Wilson explained. "As scientists begin to understand the genes that code for protective proteins, they may be able to make plants more resistant not only to diseases but to insects, wind and drought."
Scientists are comparing the Arabidopsis sequence to other fully sequenced genomes, including those of yeast, fruit flies and roundworms. By uncovering the genetic basis for similarities and differences between organisms, such work may shed light on evolution. For example, certain Arabidopsis genes appear to have moved to new locations within the genome. Further study may show how such genetic reshuffling has occurred in other organisms as well, giving them specific advantages in their environments.
The new data also will help scientists interpret the working draft of the human genome because many genes that perform basic functions have been retained during evolution. Knowing the locations and functions of Arabidopsis genes will allow scientists to pinpoint similar human genes and learn more about the causes of many disorders. "Gaining a better understanding of the functions genes perform in cells, whether plant or animal, is going to help us understand how to diagnose and treat diseases in humans," Wilson said.
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