the Genome of an Alfalfa Relative
By Don Comis
February 11, 2002
The National Science Foundation has awarded a
$1.5-million, four-year grant to scientists with the
Agricultural Research Service,
universities and the
Foundation to further unravel the genome of barrel medic, Medicago
truncatula. This is a close relative of one of the worlds top forage
crops, Medicago sativa, better known as alfalfa.
Plant pathologist Deborah A. Samac and plant physiologist Carroll P. Vance
at the ARS Plant Science
Unit, St. Paul, Minn., are working collaboratively on the genome project
with scientists at the University of
California at Davis, the
Minnesota and the Nobel Foundation.
The work may eventually help the scientists find genes that will make
alfalfa an even more profitable crop and one better suited for new uses such as
production of ethanol fuel.
The grant is a continuation of an earlier NSF grant that funded work in
which Samac, Vance and colleagues showed that most of the mapped genes for
barrel medic and alfalfa are found in the same location on each species
genome. That earlier work also showed that many genetic markers for barrel
medic can be used to find genes in alfalfa. In those studies, the scientists
identified about one-third of the 30,000 genes that are thought to be in barrel
Samac and Vance are particularly interested in finding genes that would give
the plant improved resistance to diseases and also enhance its ability to
fix nitrogen, a process in which plants can take nitrogen from the
atmosphere and change it into a form they can use as natural fertilizer to
stimulate their own growth.
New genetic techniques are making it possible for scientists to compare
thousands of genes at one time and to see which ones turn on or off in the
presence of friend or foe-- for example, disease or beneficial organisms, such
as the microbes that fix nitrogen inside of plant roots. In the
past, this type of study could only be done for a few genes at a time. The new
techniques should speed up researchers chances of finding genes that have
roles in more than one function. The scientists will research whether the
identification tags developed for barrel medics genes will help them find
similar or identical genes in alfalfa.
ARS is the U.S. Department of
Agricultures chief scientific research agency.