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United States Department of Agriculture

Agricultural Research Service

Research Project: Enhancing Resistance to Diseases and Abiotic Stresses Alfalfa

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Title: A Rapid Method for Identification of Aphanomyces euteiches Race 2 Using DNA Markers)

item Felicetti, Erin
item Larsen, Richard

Submitted to: North American Alfalfa Improvement Conference
Publication Type: Abstract Only
Publication Acceptance Date: 6/28/2010
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Aphanomyces euteiches Drechs. is an Oomycete that causes seedling root rot and poor stand establishments in alfalfa and results in stand decline of established fields with a heavy soil structure. Within the alfalfa pathotype, there have been two races identified, namely race 1 (R1) and race 2 (R2), based on the disease response of standard resistant and susceptible check cultivars. At present, the only method to identify the two races is through virulence testing which requires greenhouse evaluation over time after applying R1 and R2 inoculum to test plants. As such, DNA markers that can rapidly and unambiguously distinguish the two races would be highly useful. Nine isolates of R1 and five isolates of R2 were obtained from alfalfa fields in Illinois, Washington, and Wisconsin. DNA from R1 and R2 isolates were screened using 150 different sequence related amplified polymorphism (SRAP) primer combinations and 250 random amplified polymorphic DNA (RAPD) primers. A single SRAP marker ca 190 bp in length was identified across all five R2 isolates that did not occur in DNAs of R1. No polymorphisms were detected in R1 or R2 using RAPD primers. The SRAP marker is being developed into a sequence-characterized amplified region (SCAR) that will be useful for rapid identification of race 2. Additional SRAP and RAPD markers are being screened to identify markers specific to R1 and to obtain additional markers specific to R2

Last Modified: 05/21/2017
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