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Poster: Biology & Disease Mgmt: Genetics of Resistance


Screening soybean germplasm for resistance towards Pythium species
K. SCOTT (1), M. Eyre (1), A. Dorrance (1) (1) The Ohio State University, U.S.A.

Pythium species are a major cause of soybean seedling root rot and seed rot in Ohio. One method of management is the use of resistant cultivars. Previous studies identified a “differential” resistance response to Pythium ultimum var. ultimum and P. ultimum var. sporangiiferum among soybean cultivars. The purpose of this experiment was to quantify the resistance level of several germplasm lines and to identify any potential “differential” effect. To do this, several soybean germplasm lines were evaluated for resistance to Pythium isolates collected from fields in Ohio using a seed plate assay. Seed plate assay results indicated that Conrad, Dennison, Lorain, Sloan, and Kottman all had varying levels of resistance towards 13 species of Pythium; more importantly, there was a highly significant (P<0.0001) cultivar x Pythium spp. interaction. All cultivars were very susceptible to P. ultimum var. ultimum, P. ultimum var. sporangiiferum, and P. sylvaticum. When inoculated with P. conidiophorum, P. attrantheridium, and P. dissotocum, Conrad, Dennison, and Lorain had a lower degree of seed rot than either Sloan or Kottman. These resistant cultivars may be used to provide a higher degree of protection against infection from Pythium species in soybean seeds and seedlings.