Identification of New Sources of Resistance to Tan Spot, Stagonospora Nodorum Blotch, and Septoria Tritici Blotch of Wheat

Leaf spot of wheat (Triticum aestivum L.) in North America consists of a group of diseases involving tan spot [Pyrenophora tritici‐repentis (Died.) Drechs.], Stagonospora nodorum blotch [Phaeosphaeria nodorum (E.Müller) Hedjarroude], and Septoria tritici blotch [Mycosphaerella graminicola (Fückl) J. Schröt. in Cohn]. A complex of these diseases occurs in nature hence managing leaf spots is difficult. Use of resistant cultivars is the most effective and economical means of controlling leaf spot; however, none of the widely grown wheat cultivars in North America show high levels of resistance to these diseases. Hence, this study aimed to identify new sources of resistance to leaf spotting diseases. To achieve this objective, 975 accessions of wheat and its relatives were evaluated for P. tritici‐repentis, race 1, resistance under controlled environments. Of these 975 accessions, 40 selected accessions were further screened against six virulent races (1, 2, 3, 5, 10, and 11) of P.tritici‐repentis and to foliar pathogens P. nodorum and M. graminicola. New sources of resistance effective against the three leaf spotting disease were identified in accessions of T.monococcum L., T. turgidum L., T. dicoccum Schrank ex Schübler, T. dicoccoides (Körn. ex Asch and Graebner) Schweinf., T. timopheevii (Zhuk.) Zhuk., T. spelta L., and T. aestivum L. including synthetic wheat. Resistance was observed in all three ploidy levels of the wheat genome and presently efforts are being made to transfer the leaf spot resistance into adapted wheat and durum cultivars.