The evaluation of 391 spring wheat introductions for resistance to stem and leaf rust, loose smut and tan spot

Abstract

Three hundred ninety one (391) spring wheat introductions from Asian, Middle Eastern and Mediteranean areas were screened for resistance to races C17, C20, C25, C49, C53 and C57 of Puccinia qraminis tritici; races 1, 5, 9, 15 and bulks 1, 4 and l0 of Puccinia recondita; races T2, T10, T13 and T39 of Ustilago tritici and to 6 isolates of Drechslera tritici-repentis prevalent in western Canada. Of the 34 introductions resistant to P. graminis tritici, 15 were genetically studied using F2 segregation data derived from the progeny of the crosses involving resistant introductions, their corresponding near isogenic lines and stem rust universal suscepts. Eleven of these were found to carry single Sr genes for resistance, notably, Sr30, Sr13 and Sr15. Of the 70 introductions resistant to P. recondita, 28 were studied and 9 were found to carry known Lr genes for resistance, notably Lr10 and the genes present in RL6057 and RL6061. Twenty two introductions are believed to carry either 1 or 2 unidentified dominant, recessive, partially dominant and/or complementary genes for resistance to either stem or leaf rust. Five introductions were immune and 6 highly resistant to the 4 races of U. tritici. Sixty-nine introductions were resistant to D. tritici-repentis . These were arbitrarily classified into 10 'phenotypic classes' according to their reactions to the 6 isolates used.