ARS | Publication request: A NOVEL METHOD TO EVALUATE APHANOMYCES DISEASE RESISTANCE

Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: May 9, 2001
Publication Date: N/A

Technical Abstract: Aphanomyces cochlioides causes a seedling disease that has been considered one of the main reasons for poor stand establishment. Genetic resistance is one of the few control measures for the disease. Cysts and oospores may survive for several years in soil, weed hosts, and infected plant debris. An in vitro assay was developed that appears to mimic the natural infection nreaction in field conditions. The assay relies on three criteria. First is producing and sustaining motility of infective zoospores. Second is seedling germination in hydrogen peroxide solutions to normalize the seedling vigor differences between varieties. Third is incubating seedlings in flooding stress conditions during the course of the assay. Varietal differences were reproducible under these conditions, but the test remains to be validated. This is the first test we have evaluated that appears to predict the genetic contribution of disease resistance as distinct from the evigor component of Aphanomyces resistance.