engleski

Invasion pathways of Cryphonectria parasitica in Croatia as revealed by SCAR-typing

Introduction: Cryphonectria parasitica, causal agent of chestnut blight was first reported in Croatia in 1950´s. Since then it spread on all chestnut growing areas causing disease in forest communities across country. Aim: To evaluate genetic diversity and possible origin of the chestnut blight fungus C. parasitica in Croatia. Material and methods: Eighty-eight isolates from four locations (Cres, Hrvatska Kostajnica, Markuševac and Požega) were genotyped at 11 SCAR loci. Results: Only seven loci were shown to be polymorphic in Croatia and various diversity indices were calculated in order to reveal population structure, diversity and possible routes of invasion of C. parasitica on this territory. Among the 88 isolates 41 different SCAR haplotypes were found. Haplotype diversity indices were high, similar to those obtained by vegetative compatibility (vc)-typing of isolates from the same populations. Population differentiation was very weak but a picture of two separate introductory events in Croatia was revealed. The first invasion of C. parasitica into Croatia apparently spread from northern Italy through Slovenia and is mainly associated with two haplotypes. The second invasion probably came from southeastern Europe and is associated with a third haplotype. The vast majority of the other haplotypes found in Croatia showed recombinant allele patterns indicating genetic admixture among the introduced haplotypes. Conclusion: Our results suggest that Croatia is a place of encounter, and therefore, admixture, of western and southeastern C. parasitica populations.

Castanea sativa; chestnut blight; population structure

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