First report of breakdown of resistance gene Sr31 in Ardabil by the stem rust pathogen (Puccinia graminis f. sp. tritici) (short report)

The emergence and spread of highly virulent races of the stem rust pathogen (Ug66 race group of Puccinia graminis f. sp. tritici) threaten wheat production globally. Since the first detection of race TTKSK (Ug99) of wheat stem rust in Uganda in 1998 (4), it has been a priority to track its further spread to other wheat growing areas. To date, 10 variants of the Ug99 race group have been reported in 13 countries (3). Before of this report, virulence to Sr31 have been reported in provinces Hamadan, Lorestan (2) and Khozestan (1). Considering of the importance of the Ug99 race, during cropping season of 2015-2016, virulence of the wheat stem rust was investigated by planting of 47 isogenic lines of wheat stem rust (in national trap nursery) under field conditions. This survey was conducted in Ardabi Agricultural Research Station (38.17 ْ N, 48.39ْ E, 1350 m Height), North West of Iran. The results showed that there is no virulence for Isogenic lines having resistance genes Sr5, Sr13, Sr22, Sr24, Sr26+Sr9G, Sr27, Sr32 and Sr36. But, virulence was observed for Isogenic lines having resistance genes such as; Sr31, Sr6, Sr7. In this survey we also observed virulence of the stem rust pathogen on cultivars; MV17, Atrak and Shiroodi (with reactions 40-50 MS) which has resistance gene Sr31. The susceptible or moderately susceptible reactions of isogenic line as well as cultivars MV17, Atrak and Shiroodi having resistance gene Sr31, show probably establishment of the Ug99 or its variants in Ardabil..