engleski

Molecular identification of vegetative compatibility types of Cryphonectria parasitica, a causal agent of chestnut blight

The ascomycete fungus Cryphonectria parasitica (Murr.) Barr, causal agent of chestnut blight, is probably one of the best known invasive fungal pathogens in chestnut forests of Castanea sativ a in Europe and C. dentata in North America. In europe, the most effective known way to combat chestnut blight disease is by means of biological control utilising Cryphonectria hypovirus 1 (CHV1), which reduces virulence and sporulation of infected C. parasitica strains, converting them to hypovirulent ones. However, anastomosis-mediated, horizontal virus transmission between hypovirulent and virulent strains is hampered by vegetative (in)compatibility (vc) system involving at least six known di-allelic vic genetic loci. Traditionally, vic gene profile is determined by pairwise cultivation of isolates with EU tester strains. The goal of this study was to implement PCR-assay for routine characterization of vic genetic structure of European C. parasitica populations. We have combined already known/published and newly designed primers for amplification of six know vic loci known in European C. parasitica populations. The vc genotypes determined by PCR for 155 C. parasitica isolates tested in this study were in complete agreement with the vc genotypes determined by pairwise co-culturing of the same isolates, revealing the specificity and accuracy of the PCR-based molecular vic genotyping assay. We found 26 unique vegetative compatibility (vc) genotypes among 155 isolates, 12 of which were shared between populations and 14 unique in each one, making Croatian C. parasitica populations among the most diverse in Europe regarding the number of vc types and genetic divers ity. Unexpectedly, isolates in which both alleles at single vic loci were amplified were found, suggesting the occurrence of heterokaryonic state in these isolates. To conclude, results here validate the specificity and accuracy of the PCR-based molecular vic genotyping assay.

heterokaryon, vegetative incompatibility, vic loci

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