BARLEY POWDERY MILDEW (BLUMERIA GRAMINIS F. SP HORDEI) VIRULENCE GENE SPECTRUM IN THE SOUTHAEGEAN REGION OF TURKEY

In this study, Blumeria graminis f. sp. hordei populations taken from barley cultivation areas in 3 different periods have been analysed in terms of virulence gen frequency, virulence gen complexity, changes in pathotype frequencies, and the reactions between some of the single spore isolates and Turkish barley varieties. As plant material, susceptible Bulbul-89 barley variety and powdery mildew isogenic test genotypes, transferred through back-ross hybridization into Pallas and Siri varieties, each one having a separate resistance gene, have been used. During the harvest period of B. graminis f. sp. hordei, cleistothecia samples have been taken, and the single spore isolates taken from conidies, asexual period, and cleistothecias, sexual period, have been used as a disease material. In the B. graminis f. sp. hordei populations acquired from powdery mildew samples, first spore collection time determined 24, second sampling time determined 23 and harvest period determined 22 virulence genes. Highest virulence gene frequency has been observed in Va8 (100.00 %) gene, and lowest virulence gene frequency was observed in Vro and Vrl (0.00 %) virulence genes. Average virulence gene complexity values was found to be between 11.88-14.94 %. Differences were observed during vegetation period and harvest time in aggression gene's complexity values. Against powdery mildew disease, the most resistant barley varieties were Kaya (91.14 %) and Bayrak (88.97 %), while the most susceptible were Bulbul-89 (0.00 %) and Hilal (8.68 %).