Scientists Decode First Plant Chromosomes
12/16/99
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Title: Scientists decode plant chromosomes
Source: The Associated Press
Status: Copyright 1999, contact source for permission to reprint
Date: December 16, 1999
Scientists for the first time have decoded the DNA of a complete
plant chromosome, a milestone in understanding the deepest secrets of
the plant kingdom and a step toward developing improved crops.
Researchers unraveled the genetic structure of two chromosomes from
Arabidopsis thaliana, a member of the mustard family. That meant
identifying millions of building blocks that make up the chromosomes.
Arabidopsis has long been a favorite subject for the study of plant
genetics, because its genome - the complete collection of its DNA -
is relatively small. It is also an ideal model for gaining insights
into 180,000 other flowering plants, including corn, wheat and rice.
Two research teams, one in the United States and the other in Europe,
published the results of their work in today's issue of the journal
Nature.
Earlier this month other scientists announced the first sequencing of
a human chromosome.
Researchers are working to sequence the entire Arabidopsis genome.
"By sequencing Arabidopsis, you can use that information to infer the
basic set of genes that make up any plant," said Michael Bevan of the
John Innes Center in Norwich, England. He is coordinator of the
European Union team that sequenced Arabidopsis chromosome 4.
Arabidopsis chromosome 2 was sequenced by a team at the Institute of
Genomic Research in Rockville, Md.
Scientists expect to sequence all five Arabidopsis chromosomes by
next summer. That will be an important trial run for the sequencing
of bigger plant genomes, like those of corn and rice, which should
contain many of the same genes.
"It is not only a trial run, it has almost the same list of parts,"
said Elliot Meyerowitz, a biologist at the California Institute of
Technology who was not involved in the newly reported Arabidopsis
work.
Deciphering the genome of agricultural plants could lead to new
genetically engineered strains with improved nutritional value and
resistance to disease and pests. The issue of genetically altered
food has sparked controversy in Europe and elsewhere.
For both Arabidopsis chromosomes, about half of the genes uncovered
during sequencing have no known function. That is about the same
percentage of mystery genes being found in human and animal genomes,
said J. Craig Venter, chairman of the Rockville-based institute.
Venter said the large number of Arabidopsis genes with unknown jobs
means "we know only a small portion" of plant biology.
Genes governing such basic processes as cell division are almost
identical in plants and animals, strongly suggesting that both
descended from the same ancient one-celled organism that lived about
1.5 billion years ago, enter said.
"Some people like to think of evolution as a theory, but all you have
to do is look at the DNA level to see that these are real events that
took place," he said.