Intraspecific Genetic Polymorhism of Ganoderma applanatum (Polyporales, Basidiomycota) in Moscow Region (Russia)

Wood-destroying fungi of the genus Ganoderma are among the most widespread polypore fungi in the world. The interest in their study is constantly growing because many biologically active substances are produced by Ganoderma. The artist's bracket fungus Ganoderma applanatum is the most common species of the genus in central Russia. The objectives of this study were to characterize intraspecific genetic polymorphism in terms of sexual and somatic compatibility and to assess the variation of the ITS sequence in G. applanatum, based on 26 natural isolates collected in various localities of the Moscow region. An original technique developed to reproduce the G. appalanatum life cycle in laboratory conditions and to obtain a fertile hymenium in vitro allowed a genetic analysis of the allele diversity of mating type loci in mon-mon and di-mon crosses. At least eight alleles of the matA locus and seven alleles of the matB locus were observed in 21 G. applanatum isolates. The Shannon genetic diversity index of antagonistic reactions of vegetative incompatibility was estimated at Hvc = 1.216, suggesting a high genetic polymorphism of vegetative incompatibility determinants. Diverse phenotypic manifestations of antagonistic reactions showed that the vegetative incompatibility loci were probably multiallelic. Antagonism type did not depend on the geographic location of the isolates, and vegetatively compatible clones were detected only within the same substrate. In spite of the genetic polymorphism and multiallelic nature of the mating and somatic compatibility loci, the ITS sequences showed no divergence in the Moscow G. applanatum isolates and were assumed to provide a reliable barcode for species identification and verification of natural isolates of the fungus. Based on the results, the G. applanatum population of the Moscow region is spread over a large area, but substantial intrapopulation differentiation in terms of sexual and somatic compatibility.