Identification of new sources of resistance to tan spot of wheat

Abstract

Tan spot, caused by Pyrenophora tritici-repentis, is a major foliar disease of wheat in western Canada. Isolates of P. tritici-repentis are presently classified into 11 races based on their virulence on a set of wheat differential cultivars. In western Canada only 5 of these races have been identified. More than 1000 accessions of wheat including synthetics and wild relatives were evaluated for resistance against all the virulent races of P. tritici-repentis that are prevalent in western Canada. Disease screening was done under controlled environmental conditions at the seedling stage. High level resistance to P. tritici-repentis was observed in some accessions of Triticum monococum, T. turgidum, T. dicoccum, T. dicoccoides, T. timopheevii, and T. aestivum including synthetic wheat. These accessions also showed good resistance to the leaf spot disease stagnospora nodorum blotch. They will be studied further to determine the genetic basis of resistance and to transfer their resistance to adapted wheat and durum cultivars.