GENETICS OF VEGETATIVE INCOMPATIBILITY IN CRYPHONECTRIA-PARASITICA

Vegetative incompatibility in the chestnut blight fungus, Cryphonectri a parasitica, in Europe is controlled by six unlinked vic loci, each w ith two alleles. Four previously identified vic loci (vic1, vic2, vic3 , and vic4) were polymorphic in European vegetative compatibility (vc) types. Two new loci, vied and vic7, also were identified among Europe an ve types. In one cross, vic genes segregated independently at five loci, and 194 progeny were assigned to 32 vc types; none of these loci were linked. A total of 64 vc types mere identified from all crosses. All 64 genotypes possible from six vic loci, each with two alleles (2 (6) = 64), were identified and assigned to vc types, Based on our mode l, vc types v-c 5 and v-c 10, which had been used in previous genetic studies, differ by only five vic genes, Future studies of vc types in C. parasitica can use knowledge of vic genotypes for analysis of popul ation genetic structure based an vic allele frequencies and to determi ne the effect of each vic gene on virus transmission between vc types.