Role of sexual reproduction in vegetative compatibility type diversity of Cryphonectria parasitica, causal agent of chestnut blight, in the eastern blacksea region

This study aimed at determining vc type diversity of Cryphonectria parasitica in the Eastern Black Sea Region of Turkey and understanding role of sexual reproduction in this diversity. In 2016, cankered bark samples were collected from chestnut trees from three different locations of Artvin, Trabzon and Rize provinces and a total of 344 C. parasitica isolates were obtained. Vc types of the isolates were identified by pairing of the isolates with the European vc testers on media. Among the isolates tested, 235 isolates were compatible with the European vc testers, EU-1 (68%), 23 were EU-17 (6,7%), 21 were EU-12 (6%) and 14 were EU-3 (4%) whereas 51 isolates were not compatible with any of the European testers. The unidentified vc types were divided into six groups that were named TU-1 (6,4%), TU-2 (2,6%), TU-3 (1,2%), TU-4 (1,7%) and TU-5 (0,9%). Mating types of 179 isolates were detected by using a PCR with spesific primers. MAT-1 and MAT-2 comprised of 37,4% and 55,3%, respectively. Thirteen isolates were heterokaryotic carrying both mating alleles. Perithecia were found in 130 bark samples, evidencing that C. parasitica commonly reproduce sexually in the region. Single ascospore isolates were obtained from the perithecia of 21 field cankers and at least 25 single isolates per perithecia were subjected to the vc type assay. Numerous single ascospores from 14 cankers showing vegetative incompatibility with the parent isolates were detected. The results indicated that the diversity of vc types of C. parasitica increases in te Eastern Black Sea Region and this increase can partially be related to the sexual reproduction. Key words: Chestnut blight, Cryphonectria parasitica, vegetative compatibility, mating type, sexual reproduction, vc type diversity