Genetic analysis of brown stem rot resistance in soybean

Genetic analysis of brown stem rot resistance in soybean

1989

A:PS

Genetic resistance of soybean [Glycine max (L.) Merr.] to Phialophora gregata (Allington and Chamberlain) W. Gams, the cause of brown stem rot (BSR), can reduce yield losses in northern USA and Canadian production regions. Although two major dominant genes have been identified, additional sources of resistance may provide higher levels of resistance and/or more stable resistance over environments. The objectives of this study were to: (i) determine the pattern of inheritance of the BSR resistance found in PI 437970 and (ii) study allelic relationships of resistance genes in PI 437970 with Rbs1, and Rbs2. Evaluations were conducted using a root dip inoculation method in the field and greenhouse. The F2 and F3 plants were classified as resistant or susceptible based on mean parental reactions. Segregating generations of the cross PI 437970 x `Pioneer Variety P9271` revealed a single dominant gene conditioning BSR resistance. Crosses of PI 437970 with L78-4094 (Rbs1) and PI 437833 (Rbs2) each demonstrated duplicate dominant epistasis indicating a third distinct gene designated Rbs3. [AS]

v.29(3):672-674, CROP SCIENCE

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