Inheritance of Crown Rust Resistance in Avena Sterilis1

Abstract

The inheritance of resistance in three collections of Avena sterilis (F83 and F366 from Israel, and CW491‐4 from Algeria) to races 264, 290, 295, 332, and 446 of crown rust, Puccinia coronata avenae, was investigated. Genetic analysis indicated that two of the collections (CW491‐4 and F366) each had a single gene (Pc‐38 and Pc‐39 respectively), independent of each other, which conditioned resistance to these five races of crown rust and to every other isolate to which they were tested.Four distinct genes for crown rust resistance were discovered in the third A. sterilis collection, F83. Gene Pc‐40 was epistatic to the other three genes in F83, and conditioned resistance to races 290, 295, 332, and 446, but not to race 264. Gene Pc‐41 conferred resistance to races 290, 295, and 332, while gene Pc‐42 was effective only against race 332 and gene Pc‐43 only against race 290. Some backcross families of F83 that were susceptible to all five of these races segregated for resistance to a few of the other crown rust races against which they were tested, indicating the presence of an additional gene. Genes Pc‐38, Pc‐39, Pc‐40, and Pc‐42 all conditioned fleck type resistance. Gene Pc‐41 conditioned intermediate type 2 resistance, while gene Pc‐43 was incompletely dominant and conditioned either fleck or type 2 resistance.