Pathotype Determination of the Mycosphaerella graminicola Cause of Septoria Leaf Blotch of Wheat in Iran

Nevertheless, Septoria leaf blotch disease management relies mainly on successful strategies of breeding for resistance which depends on primary data of pathotype of the pathogen population and their virulence in infected areas. In this research, 23 strains were individually inoculated on 19 differential wheat cultivars in seedling stage under greenhouse condition and pathotype determined. Results showed that differences due to cultivars and isolates were highly significant at 1 levels.The cultivar x isolate interaction component was relatively very small and not significant that showed isolates would thus not vary in aggressiveness and cultivars in race- nonspecific resistance. None of the isolates had virulence on cultivar TE 9111 carrying Stb6, Stb7 and Stb11. Since the virulence was observed on some cultivars carrying Stb6 and/or Stb7 by specific isolates, then the resistance of TE 9111 can be attributed to Stb11. Maximum and minimum frequency of virulence were observed on Boolani (general susceptible control), Taichung 29 (international control, susceptible to the standard isolate IPO323) by 69% and Estanzuela Federal (carrying St 7) by 66%, and on TE9111 (carrying Stb4 and Stb6) by 4% and Oasis and Sulivan (carrying Stb1) by 9% and 11% respectively. Virulence frequency of isolates on other wheat cultivars carrying different Stb genes was varied between 16 to 59%. Three isolates proved to be one pathotype by showing the same virulence pattern on Stb genes, whereas other isolates showed different virulence patterns on wheat differential cultivars. This study identified 18 M. graminicola pathotypes which shows a high genetic diversity among the Iranian pathogen populations.