Making the Most of Disease
Resistance
Researchers find in a collection of cultivated and wild potato
many genetic sources of disease resistance to meet future
needs.
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Traditional diseases mutate, and new threats to the major food
crops of the world continually emerge. Climate change will only
make these problems worse. At the International Potato Center (CIP)
in Lima, Peru, breeders are preparing for coming battles by working
t o maintain a continuous flow of genetic diversity to use in
breeding work. A team of CIP scientists is systematically looking
for new and varied sources of robust resistance to disease in the
collection of wild and cultivated germplasm conserved and held in
trust by this agricultural research Center supported by the
CGIAR.
Late blight is one of the worst diseases affecting potato.
Breeding for resistance to late blight started in the 1920s, but
the fungus-like organism that is responsible for the disease,
Phytophthora infestans, mutates continuously, so that
varietal resistance is rapidly overcome if it has a narrow genetic
basis.
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Photo: Paul Stapleton
Wild species of Andean potato are proving to be a valuable source
of extreme disease resistance.
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The strategic use of genetic resources, including wild relatives
native to regions with year-round pressure from Phytophthora
infestans, is a key to improving potato's resistance to
late blight. A broad genetic base of resistance is expected to be
more lasting, as it should delay the pathogen's ability to
overcome the genes and mechanisms responsible.
"We want to make wild species' resistance more amenable
for use in breeding populations," says Dr. Meredith Bonierbale
of CIP, who runs the project.
Four species have been found that are strongly resistant to late
blight, and work progresses to develop hybrids as upgraded sources
of traits for further breeding. " Our interdisciplinary
approach to the screening and characterization of late blight
resistance in these groups represents the essential first step
towards the efficient transfer of late blight resistance from
underutilized wild species to the cultivated potato," says
Bonierbale.
New sources of resistance to the economically important potato
leaf roll virus (PLRV) have also been identified among CIP genebank
accessions, confirming again the valuable potential that can exist
in a comprehensive collection of genetic resources.
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