Title: Discovery offers hope of saving sub-Saharan crops from devastating parasites
[University of Toronto Sept. 10, 2010] Each year, thousands of acres
of crops are planted throughout Africa, Asia and Australia only to be laid to
waste by a parasitic plant called Striga, also known as witchweed. It is
one of the largest challenges to food security in Africa, and a team of
scientists led by researchers from the University of Toronto have discovered
chemicals and genes that may break Striga's stranglehold.
When crops
grow, their roots release a plant hormone called strigolactone. If the soil
contains Striga seed, it will use the released strigolactone as a cue to
germinate and infect the crop plants. Once connected to the crop, the Striga
plant kills the crop by sucking out its nutrients. "In sub-Saharan Africa alone,
Striga has infected up to two-thirds of the arable land," says U of T cell and
systems biologist Peter McCourt, principal investigator of a study published
this week in Nature Chemical Biology. "With chemicals and genes
in hand that influence strigolactone production in plants, we should be able to
manipulate the level of this compound by chemical application or plant breeding
which would break the Striga-crop interaction".
The scientists used a
model genetic plant system called Arabidopsis to screen 10,000 compounds and
identify a set of five chemicals, designated cotylimides, which increase the
accumulation of strigolactone in plants. They also found related chemicals
that decrease strigolactone levels. From there, they screened for mutants
of Arabidopsis that were resistant to cotylimides and identified mutants that
made less strigolactone. These mutants identified genes that regulate
strigolactone levels in plants.
The full study
is available on Nature Chemical Biology's website.
The research
team includes members from the University of Toronto's Department of Cell and
Systems Biology and Centre for Analysis of Genome Evolution and Function, as
well as the RIKEN Plant Science Center in Yokahama, Japan.