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Breakthrough in Fight against Deadly
Potato Disease
"It's true," says CIP plant pathologist Sylvie
Priou, "We have found that seven genotypes from two wild
Andean potato species have high levels of resistance to wilt and
tuber infection." This is the first real proof of bacterial
wilt resistance in nature. And since the resistance comes from a
wild relative of the domesticated potato its transfer to commercial
varieties should not be too difficult.
Bacterial wilt is the number two constraint on potato production
in over 40 developing countries. More than four million hectares
are infected, causing damage estimated to exceed one billion US
dollars annually. Tens of millions of farm families are affected,
suffering yield reductions that can amount to total loss.
With operational funding from the Wallace Genetics Foundation,
the Conservation Food and Health Foundation and the International
Foundation, Priou and her team at CIP have spent four years on a
large-scale screening effort. In first-of-their-kind-tests
conducted during 2004, genotypes that showed resistance were
re-exposed to the pathogen in less severe conditions, to assess the
presence of latent infection in tubers. Seven wild potato genotypes
came through with flying colors, exhibiting high levels of
resistance to both wilt in the stems of mature plants and latent
infection in the tubers. Studies to identify the mechanisms and
genetic basis of the resistance will proceed during 2005, before
the trait is transferred to commercial potatoes - and thence to the
fields of farmers in developing countries. "I'm 90%
certain that our final tests will confirm the resistance we have
already seen," says Priou," just a few more months
..."
To have found a source of resistance to this scourge is a major
breakthrough that could ultimately increase productivity by 10%
across the developing world and by substantially more in the most
severely afflicted regions.
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Brown rot
(photo courtesy of CIP)
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Bacterial wilt symptoms in potato caused by
Ralstonia solanacearum
(photo courtesy of CIP)
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CIP's Alberto Salas (taxonomist) and Sylvie Priou
(pathologist) checking out the growth of the wild potato plants in
the greenhouse
(photo courtesy of CIP)
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Solanum acaule-resistant and susceptible
genotypes after exporsure to bacterial wilt pathogen
(photo courtesy of CIP)
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