PROMISING OUTLOOK FOR FUSARIUM WILT RESISTANCE IN PEAS
September 16, 2003
Western Grains Research Foundation
www.westerngrains.com
Saskatoon, Sask.: Researchers have discovered potential genetic resistance
in field peas to Fusarium wilt, a fungal disease that causes premature plant
death. The Agriculture and Agri-Food Canada (AAFC) scientists identified the
material by scanning the genetic 'bank' of field pea germplasm and
cultivars, and will now use the most promising material to develop wilt
resistant pea cultivars adapted for Prairie conditions.
The Fusarium wilt (Fusarium oxysporum f.sp. pisi) pathogen is among the
major diseases threatening field pea production on the Prairies. A
soil-borne fungus, it causes yield losses and severe infections that can
completely spoil a pea crop. Fusarium wilt occurs wherever peas are grown
and it can survive in fields for up to ten years.
"Breeding for resistance to Fusarium wilt in field peas has had little
success due to lack of information about the makeup of the pathogen and
because the availability of resistance in existing breeding material has not
been determined," says Dr. Bob Conner, pathologist at the AAFC Cereal
Research Centre in Morden (Morden Research Station), Man.
Conner led the project along with colleagues Dr. Allen Xue, plant
pathologist
at AAFC Eastern Cereal and Oilseed Research Centre in Ottawa and Dr. Ron
Knox,
biotechnologist at AAFC Semiarid Prairie Agricultural Research Centre in
Swift Current. The scientists recently completed a three-year study on
Fusarium wilt and resistance inherent in various pea cultivars. The research
was supported, in part, by the Western Grains Research Foundation (WGRF)
Endowment Fund.
Previous U.S. research indicated the existence of four races of the Fusarium
wilt pathogen. To determine what races are present in western Canadian pea
fields, a survey was performed where infected plant material was collected
from more than 100 sites in Manitoba, Saskatchewan and Alberta over three
growing seasons (1999 to 2001).
"Three out of four known races of Fusarium wilt were identified in the
collected plant material," says Conner. "Two of these races are highly
virulent, including the race that was found to be most widespread."
To determine the availability of Fusarium wilt resistant breeding material,
the research team evaluated the symptoms of 117 field pea varieties that had
been exposed to the disease.
"Cultivars Radley and Princess were found to be resistant to the two most
virulent Fusarium wilt races identified in the field survey and 39 percent
of the cultivars were resistant to the least virulent race," says Conner.
"Remaining cultivars, nearly 60 percent, were found to be susceptible to all
pathogen races."
Breeders at the Morden Research Station will now include the most promising
resistant field pea cultivars in the breeding program in order to transfer
the wilt resistance genes into agronomically superior pea varieties, he
says.
"We actually detected resistance in some of the advanced breeding lines from
the breeding program," says Conner. "These lines have to be put through
final screening and evaluation, but should then become available on the
market."
Using new screening procedures, labour and time involved with screening is
greatly cut, he adds. The new screening procedures have proved efficient and
reliable and are becoming standard protocol for these types of laboratory
tests.
In an effort to further enhance breeding efficiency, the researchers also
identified molecular markers for the resistance gene associated with the
most common Fusarium wilt race.
Eight significant markers showed promise as selection tools but some
modifications are still needed to make them useful to breeders, he says.
"The ultimate goal is to provide producers with new field pea varieties that
have a package of resistance genes for Fusarium wilt and other diseases,"
says Conner. "This would provide the best option for long-term pathogen
control and increase the appeal of peas as a Prairie crop."
Western Grains Research Foundation is a major farmer funded and directed
grains research funding organization in Western Canada. WGRF allocates
approximately $5 million annually to research through the Wheat and Barley
Check-off Funds, and a separate Endowment Fund.