ALLELE AND GENOTYPE FREQUENCIES OF THE INTERGENIC RDNASPACER ONE REGION IN ECTOMYCORRHIZA POPULATIONS OF XEROCOMUS PRUINATUS ON THREE DIFFERENT HOST TREE SPECIES

摘要

The variability of the intergenic spacer IGS1 of the rDN A cluster in six populations of the ectomycorrhiz-al basidiomycete Xerocomus pruinatus Fr. Quel. is described. In X. pruinatus populations on European beech Fagus sylvatica, sessile oak Quarcuspetruea and Norway spruce Picea abies the IGS1 exhibits two alleles and three genotypes.Genetic measurements indicate that sexual reproduction is important for the genetic structure in this late stage ectomycorrhizal fungus.In association with the two angiosperms beech and oak the homozygous genotype aa and the heterozygous genotype ab dominate, whereas in association with the gymnosperm spruce the homozygous genotype bb predominates. The corresponding allele b was statistically more frequent in the X. pruinatus population on Norway spruce than in populations on European beech and a population on sessile oak. Genotype preferences are discussed in the context of adaptation and coevolution.