Spatial distribution and temporal persistence of discrete genotypes of the ectomycorrhizal fungus Laccaria bicolor (Maire) Orton



A field study was conducted to determine the spatial distribution and temporal persistence of Laccaria bicolor (Maire) Orton genotypes associated with naturally colonized Norway spruce [Picea abies (L.) Karst.] in a plantation. Groups of sporophores around three trees Were mapped and collected over two to tour consecutive autumn seasons to isolate cultures and determine their genetic relatedness by mating type and randomly amplified polymorphic. DNA (RAPD) analysis. Annual sporophore distribution varied significantly on all sites, with an increase in the mean radial distance from the trees over the study period. Sporophore distribution was discontinuous and characterized by clumped groupings around trees. Sporuphores with the same mating type and disparate distributions were present on each of two sites during the sample period. RAPD analysis for each of the six random primers detected the same DNA polymorphisms for all dikaryotic isolates tested from a given site over the sample period. These results provide evidence that a single genetic individual of L. bicolor can remain associated with a host root system for at least 3 yr and vary significantly in us spatial distribution. This is the first instance in which the persistence of specific genotypes of an early–stage ectomycorrhizal fungus has been demonstrated for a tree colonized by natural sources of inoculum. The implications of these findings are discussed in relation to the ecology and succession of ectomycorrhizal fungi.