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Tough new potatoes take on double trouble

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Tough new potatoes take on double trouble
Five new potato breeding lines being tested by Agricultural Research
Service (ARS) scientists and collaborators could open the door to new varieties
of the crop that resist powdery scab and black dot diseases, caused by the
fungi Spongospora subterranea and Colletotrichum coccodes, respectively.

March
12, 2010 – Five new potato breeding lines being tested by Agricultural Research
Service (ARS) scientists and collaborators could open the door to new varieties
of the crop that resist powdery scab and black dot diseases, caused by the
fungi Spongospora subterranea and Colletotrichum coccodes, respectively.

These
fungi often occur together in the same soil, attacking the potato plant’s
roots, tubers or stems. Outbreaks can cause yield losses of up to 25 per cent
and prevent tubers from reaching the sizes needed by the French fry and
fast-food industry. Of the two fungi, only black dot can be chemically
controlled with fungicides; however, multiple applications are needed,
ratcheting up production costs to prohibitive levels. A more sustainable
alternative is genetic resistance, according to geneticist Chuck Brown, with
the ARS Vegetable and Forage Crops Production Research Laboratory in Prosser,
WA. 

In
studies conducted there since 2004 with Washington State University professor
Dennis Johnson, assistant Tom F. Cummings and postdoctoral associate Nadav
Nitzan, Brown screened an existing collection of wild and cultivated potatoes
for sources of natural resistance to powdery scab and black dot in a local
grower’s infested field.

The
effort ultimately led to five advanced potato breeding lines that had been
developed from a wild species from Mexico, Solanum hougasii, and a recent
commercial release, Summit Russet. In three years of field trials in Washington
State and Idaho, the potato breeding lines consistently showed fewer disease
symptoms-root galling for powdery scab and sclerotia-infected stems for black
dot-than other lines and varieties tested.

The
potato breeding lines themselves aren't intended for production. Instead,
they'll be made available as seed for use in breeding programs aimed at
developing the first commercial varieties with dual resistance to the fungal
diseases, according to Brown, who discussed the research at the 48th Annual
Washington State Potato Conference in January. 

The
research findings have been published in the journal Plant Disease.