The potential diversity of vegetative compatibility types in the population of Cryphonectria parasitica in Turkey

The diversity of vegetative compatibility (vc) types of chestnut blight fungus, Cryphonectria parasitica, has been reported to be very low in all of Turkey, except in the eastern Black Sea Region. However, risk for increase in vc type diversity has been pointed out regarding the emergence of new vc types as recombinants during sexual reproduction. In this study, the potential increase in the diversity of vc types in Turkish populations of C. parasitica was demonstrated by experimental mating crosses between the two dominant vc types, EU-1 and EU-12. Two local isolates of C. parasitica, K5-5 (EU-1) and A-2490 (EU-12), were used setting crosses on autoclaved chestnut wood. Among the offspring from the crosses, two parental (EU-1 and EU-12) and 14 non-parental vc types (EU-2, EU-3, EU-4, EU-7, EU-8, EU-11, EU-14, EU-17, EU-22, EU-25, EU-26, EU-28, EU-29 and EU-30) were detected by a routine test based on co-culturing. Sixteen vc genotypes were confirmed by a PCR assay using specific primers targeting the alleles of six vic loci in C. parasitica. In field studies, no evidence of new vc types as recombinants was found in western Turkey whereas 14 different vc types were detected among single ascospore isolates isolated from field-collected perithecia, which were sampled from the eastern Black Sea region. The results of this study indicate that the potential increase in vc type diversity in Turkish population of C. parasitica is high under the conditions where C. parasitica reproduces sexually.