Identification of virulence factors of Mycosphaerella graminicola, the causal agent of septoria leaf blotch of wheat by trap nursery
2014
Roohparvar, Ramin | Kia, Shaban | Dalvand, Mohammad | Hassan-Bayat, Zohreh | Arazi, Vali
Virulence of plant pathogens on host resistance genes should be highly considered in breeding programs for diseases in their hot spots. In order to investigate the virulence of Mycosphaerella graminicola, the septoria tritici blotch (STB) pathogen of wheat in field condition, trap nursaries were planted in Gorgan, Gonbad and Dezful (and in Karaj for seed multiplication). In total, 398 national and international wheat genotypes were evaluated during three cropping seasons of 1387-90, including 95 genotypes of the 3rd international Septoria tritici trap nursery (3rd ISTTN-08, Syria), 54 commercial cultivars, 171 selected advanced lines of Cereal Research Department, 28 DARI genotypes, 30 selected international genotypes, and 20 differential cultivars for the pathogen. Genotypes were linearly planted in two rows of 1 m with 30 cm space. Disease severity was evaluated as reaction of the genotypes based on 00-99 double digit scale of Saari & Prescott modified by Eyal et al. Due to unfavorable environmental conditions for the disease development (due to severe dry season) and lack of primary inoculum, the reaction of genotypes was assessed only in Gorgan and Dezful in the first and second years, respectively. Results of the first year showed that in Gorgan 46 and 19 lines were susceptible, and moderately susceptible, respectively, whereas the rest of 200 genotypes tested showed immunity. Despite lack of disease development in Dezful, one line was evaluated as moderately susceptible. In the second year, the disease symptoms were not observed on 92% of the total of 217 wheat lines tested, whereas 2 and 6% of the genotypes were evaluated as moderately susceptible and susceptible to STB pathogen, respectively.
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