Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2003
Publication Date: June 1, 2003
Citation: VANDEMARK, G.J., GRUNWALD, N.J. QUANTIFYING APHANOMYCES EUTEICHES IN PEA WITH A REAL TIME FLUORESCENT PCR ASSAY. PHYTOPATHOLOGY. 2003. 93:S86. Technical Abstract: Aphanomyces euteiches causes severe root rot of peas. Resistance is limited in commercial pea cultivars. Lack of progress in breeding for resistance may in part be due to limited discriminatory power of typical screening procedures, which rate disease severity using an integer scale. We developed a real time fluorescent PCR assay specific for A. euteiches. The susceptible cultivar Genie and the moderately resistant breeding line 180693 were inoculated with two different pathogen isolates. Plants were rated for disease severity using an index of 0 (healthy) ' 5 (extreme root necrosis) and the amount of pathogen DNA in roots was determined using the PCR assay. In independent experiments, using two different inoculum levels for both pathogen isolates, significantly more pathogen DNA was detected in the susceptible cultivar than in the moderately resistant population. In seven of eight experiments the Spearman correlation between pathogen DNA quantity and disease severity index was positive and significant (P < 0.05). The real time PCR assay may be a useful selection tool to discriminate among plants that are indistinguishable based on visual assessment of disease severity.