Submitted to: Proceedings of the 2002 Mycological Society of America Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2002
Publication Date: 7/1/2002
Citation: VANDEMARK, G.J., BARKER, B.M. DISCRIMINATION OF ALFALFA POPULATIONS FOR RESISTANCE TO APHANOMYCES EUTEICHES USING A REAL TIME FLUORESCENT POLYMERASE CHAIN REACTION ASSAY WITH BULKED PLANT SAMPLES. PROCEEDINGS OF THE 2002 MYCOLOGICAL SOCIETY OF AMERICA ANNUAL MEETING, JUNE 2002, Corvallis, OR, p. 84 (abstract) 2002.
Technical Abstract: A PCR assay using a set of specific primers and probe (TaqMan) was developed to quantify the amount of Aphanomyces euteiches DNA in alfalfa plants exhibiting varying levels of disease severity. The study included two isolates each of race 1 and of race 2 of A. euteiches. Analysis of individual plants and bulked plant samples of standard check populations with each isolate resulted in Spearman rank correlations between pathogen DNA content and disease severity index (DSI) ratings that were greater than 0.75 and highly significant (P<0.001). In experiments with both race 1 isolates, the amount of pathogen DNA present in the resistant check WAPH-1 was significantly less than in the susceptible check Saranac. In experiments with both race 2 isolates, the amount of pathogen DNA in the resistant check WAPH-5 was significantly less than in either of the susceptible checks, Saranac and WAPH-1. Similarly, the assay demonstrated that significantly less A. euteiches DNA was detected in the roots of a resistant pea line than in a susceptible line. A similar assay has been developed for Phytophthora medicaginis, which also causes root rot in legumes. These assays may be useful for breeding programs for selecting among plants that appear phenotypically similar based on visual assessment of disease symptoms.