Epistasis and maternal effect in resistance to Puccinia coronata Cda. f. sp. avenae Eriks in oats (Avena sp.).

The objective of this paper was to investigate the mode of heredity for resistance in oats (Avena sp.) to crown rust caused by Puccinia coronata Cda. f. sp. avenae Eriks. Eight generations of 2 crosses were used to estimate genetic effects and narrow-sense heritability (NSH). Separate generation means analysis (GMA) indicated a complex gene action controlling this trait with additive, dominance, epistatic and maternal effects (ME). The genetic model which assumed no epistasis and no ME did not accurately describe the resistance to P. coronata. In both crosses, the digenic epistatic model with ME was sufficient to explain variation in generation means for isolate CRPc58 and isolate CRPc46. Additive dominance and epistatic components were negative in most cases, suggesting that gene effects contributed more to the resistance than to the susceptibility. The estimated values of NSH were 15-99% depending upon the cross and isolates. The results indicated that appropriate choice of maternal parent and recurrent selection would increase resistance to crown rust in oats.