Washington, DC, USA
March 6, 2012

Source USDA-ARS via ASTA newsletter

Eight new green pea breeding lines developed by Agricultural Research Service (ARS) scientists and their collaborators could give legume growers added insurance against costly outbreaks of the fungus-like pathogen that causes Aphanomyces root rot.
Considered the most destructive pathogen of peas worldwide, Aphanomyces euteiches attacks the root systems of susceptible plants, stunting their growth and causing the roots to become soft, discolored and decayed. Aphanomyces root rot can be responsible for serious damage to pea crops, and entire fields may be lost, according to Rebecca McGee, a plant geneticist with the ARS Grain Legume Genetics and Physiology Research Unit in Pullman, Wash.

The new breeding lines (RIL series 846-07, 847-08, 847-22, 847-45, 847-28, 847-50, 847-53 and 847-68) are described as "partially resistant." The plants can still develop symptoms of root rot, but those symptoms are much less pronounced than in susceptible peas. Another advantage: The partially resistant peas can produce reasonable yields even when grown in fields infested with the pathogen. Current control methods include ensuring soils are adequately drained, avoiding planting in heavily infested fields, and rotating peas with non-host crops. The cornerstone defense, however, is to plant cultivars that can withstand the disease.

The new peas were jointly developed, evaluated, genetically mapped and released by McGee and her colleagues at ARS, North Dakota State University and the French National Institute for Agricultural Research. The lines owe their partial resistance and other desirable traits to a cross made in 2002 between "Dark Skin Perfection," which is a wrinkled pea cultivar, and 90-2131, an ARS germplasm line.

The peas' agronomic characteristics include white flowers and straight, blunt green pods suitable for fresh-, freezer- or dry-pea markets. Field tests were conducted for four years at two U.S. sites (Pullman, Wash., and Le Sueur, Minn.) and two French sites (Riec-sur-Belon and Dijon). All of the new pea lines tolerated Aphanomyces root rot better than the parent lines used to develop them, though some fared better than others against the highly virulent French isolate RB84.
 

Website: http://www.ars.usda.gov

Published: March 6, 2012