Effectiveness of Septoria tritici Blotch (Stb) Resistance Genes to Mycosphaerella graminicola Isolates Collected from Fars Province

Septoria tritici blotch (STB)، caused by Mycosphaerella graminicola (anamorph، Zymoseptoria tritici) is considered as an important destructive disease of wheat worldwide as well as Iran. In order to study the virulence spectra of isolates collected from Fars province on the differential cultivars possessing Stb resistance genes، pathogenicity tests using seven isolates were conducted under controlled conditions in 2013 at Seed and Plant Improvement Institute in Karaj based on 0-5 scaling system. Out of 126 M. graminicola-wheat interactions، 41 specific resistances and 85 susceptible interactions were found. Except RM186 and RM177 that had similar virulence pattern، the remaining isolates exhibited distinct virulence patterns indicating that these isolates had genetic differences. Isolates RM9، RM175 and RM179 were the least virulent isolates that were pathogenic on 9 out of 18 differential cultivars. Isolates RM28 and RM159 were virulent on 16 differential cultivars and thus، were considered as the most virulent isolates. The results showed that among resistance genes، Stb16/Stb17 presented in M3 cultivar were effective against all isolates. None of the Stb5، Stb6، Stb7 and Stb8 genes was effective against isolates tested. These results can be used in wheat breeding programs for resistance to septoria tritici blotch disease in Fars province.