Scientists Turn Genetic Keys to Unlock Bioenergy
in Switchgrass By Jan Suszkiw April
Using genetic "snapshots" of switchgrass, Agricultural Research
Service (ARS) and collaborating
scientists are gaining new insight into how this warm-season perennial plant
could be harnessed as an ethanol resource.
The snapshots are actually fragments of genetic material called
messenger RNA (mRNA), and they're like molecular workhorses that do the bidding
of DNA (deoxyribonucleic acid). One key task is delivering instructions to make
Over the past few years, ARS molecular biologist
Sarath and colleagues have generated tens of thousands of the mRNA
snapshots depicting switchgrass from the moment it sprouts from seed to the
time it girds itself for winter.
Determining the nucleotide sequences of the mRNA snapshots provides
clues as to which genes have been turned on or shut off during such moments,
according to Sarath, at the
Grain, Forage and Bioenergy Research Unit in Lincoln, Neb.
Since 2003, Sarath, Paul Twigg of the University of Nebraska-Lincoln and
Tobias, a molecular biologist with ARS in Albany, Calif., have determined
the sequences of about 12,000 switchgrass gene fragments. At least 12 of them
are associated with genes that regulate the production and deposition of
lignin, the cementing agent that holds plant cell walls together.
Bioenergy producers are keen on loosening the grip of lignin so that
more of the sugars locked within the cells of switchgrass can be fermented into
ethanol. Currently, sugars from the starch of grain crops like corn are used.
One possible approach is to conventionally breed or genetically engineer new
varieties of the grass with a diminished capacity to produce lignin.
To speed the discovery of important genes besides those for lignin
production, the ARS scientists submit the genetic fragments they amass to the
U.S. Department of Energy's Joint Genome
Institute in Walnut Creek, Calif. There, scientists employ state-of-the-art
sequencers so that the fragments' identities and function can be more quickly
determined through comparisons to the genomes of corn, rice and other grasses.
about this and other ARS bioenergy research in the April 2007 issue of
Agricultural Research magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.