Virginia
July 5, 2007
 The
black-eyed pea is a well-loved legume in the southern United
States. Some call it “soul food”; others call it good luck when
eaten on New Year's Day.
In its native region of western and central Africa, the
black-eyed pea — known by the name “niebe” in Francophone
countries and as “cowpea” in the English-speaking regions — is a
primary protein source for millions of people. About 80 percent
of the world's cowpea crop is grown there, mostly by subsistence
farmers. The entire plant is used — the pea for soups, stews and
breads, the leaves as fresh greens, the stems as hay and fodder
for cattle.
Unfortunately, as the cowpea plant evolved over time, so did a
parasitic plant that starves the cowpea plant to death by
sucking nutrients from its roots. This parasitic plant, Striga
gesnerioides, or “witchweed,” is so virulent that farmers must
relocate their cowpea crop to new soil every few years. But
because Striga’s seeds are as fine as dust, farmers
inadvertently carry the witchweed seeds wherever they plant
their cowpeas. It's a major problem in a dry region where
farmers lack money for herbicides and fertilizers and must
continually rotate their crops back to tired dry soil already
infested with Striga seeds.
Michael Timko, a University of
Virginia Professor of Biology, is working hard to solve ”the
Striga problem,” as it's called in west Africa. He and other
scientists have sequenced the cowpea genome and are using this
information to help develop Striga-resistant cowpea plants.
“It is now possible for us to identify all possible genes for
Striga resistance in cowpeas, as well as resistance to other
cowpea pathogens,” Timko said. “We may even eventually breed a
more drought-resistant plant and varieties that have higher
levels and a better balance of nutrients. We've reached a point
where we can manipulate this plant for the good of millions of
people.”
Because of various political, social and ethical issues
associated with introducing genetically modified crops in
Africa, the use of transgenics is not an option at the present
time. Therefore, Timko’s approach is to improve the performance
of plants by identifying genes that control key characteristics,
and then use this knowledge in selective breeding programs that
emphasize those traits using associated genetic markers. The
resulting product is the delivery of improved parasite-resistant
hybrids to the farmer in shorter amounts of time.
Timko is working with African breeders and growers and training
African scientists in his lab at U.Va. in the use of modern
molecular breeding techniques. In recent years he has brought
more than 20 African graduate students and postdoctoral fellows
to study in his lab, most of them staying for three months to a
year. Some of them are now department chairs and directors of
major labs in Africa.
“We've created a great international environment,” Timko said.
“Right now there are two students from Ghana and one from
Zimbabwe working in the lab.”
Timko is also seeking funding to send U.Va. undergraduate and
graduate students to west Africa to learn firsthand about
African agricultural practices. “The Africans are coming here to
learn, but our students should also be going there,” he said.
Timko makes regular trips himself, visiting six times last year
to build on his already strong relationships.
While Timko’s research is successful, it is complicated work
that will take years to measure out. One challenge is that there
are at least seven different races of Striga, each capable of
adapting to changing varieties of cowpeas.
“We are trying to create a plant that is resistant across the
board,” Timko said. ”But the parasite responds over time to
whatever we do. Striga is hyper-virulent. This is warfare
between the cowpea plant and its parasite, and we keep trying to
stay ahead of the enemy.”
For centuries, farmers have been modifying and improving their
crops through selective breeding, a trial-and-error approach.
“We simply speed up and improve the breeding process by using
modern molecular-based technologies,” Timko said. “It’s a
logical progression of the hybridization process. It's
satisfying work, knowing that we are able to take research from
our lab to the field that can directly improve people’s lives
and well-being.” |
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