Inheritance of resistance to Puccinia coronata Corda and Rhynchosporium orthosporum Caldwell in Italian ryegrass

Summary Progeny analysis within Italian ryegrass (Lolium multiflorum) cv. RvP infected with a single clone of crown rust (Puccinia coronata f. sp. lolii) revealed major factors, one probably a single dominant gene, conferring resistance in two of twelve randomly selected parents. The remaining variation in resistance to this pathogen, and all of the variation in resistance to Rhynchosporium orthosporum, was controlled by a relatively large number of minor genes exhibiting neither dominance nor epistasis. There was no significant maternal inheritance. Absence of any correlation between progeny scores for reaction to the two pathogens indicated that resistance to each was inherited independently.