Virulence and Mating Type Distribution of Didymella rabiei in Chickpea Growing Areas of Turkey

Chickpea (Cicer arietinum L.) is a traditional crop species in Turkey that is cultivated in almost every province providing prominent economic income. Turkey has an important resource for both Cicer spp diversity and their phytopathogens like ascohyta blight caused by Didymella rabiei (Kovachevski) von Arx wherein resistance/tolerance is broken every 4-5 years in cultivated chickpea cultivars. In order to breed resistant/tolerant varieties in chickpea against D. rabiei, detailed and up to date analyses on population characterization is needed. This study was undertaken to define current aggressiveness patterns, pathotype and mating type distribution of D. rabiei population in chickpea growing areas of Turkey. The D. rabiei isolates were assigned to 5 virulence groups in which existence of pathotype IV, a new and aggressive group, was defined for the first time from farmers’ fields and research institutes exhibiting continuous arm race between plant and pathogen. The isolates in each pathotype group depicted statistically important difference (P≤ 0.05) in virulence levels on chickpea genotypes. The mating type distribution of 971 D. rabiei isolates was 1:1 for Mat 1.1 and Mat 1.2 isolates (X2= 0.87, P= 0.35) exhibiting random sexual reproduction. Overall, the data obtained revealed the unstable aggressiveness nature of D. rabiei population in Turkey, which, in turn, explains frequent resistance overcome in registered chickpea genotypes leading to epidemics.