Genet distribution of sporocarps and ectomycorrhizas of Suillus pictus in a Japanese white pine plantation

• Spatial distribution and biomass of genets of sporocarps and ectomycorrhizas of Suillus pictus were studied in a plot of 20 × 24 m established in a Pinus pentaphylla var. himekomatsu plantation. • The biomass of S. pictus ectomycorrhizas was evaluated based on morphotypes, and genets were identified based on the inter-simple sequence repeat (ISSR) polymorphism analysis. • Suillus pictus was one of the dominant ectomycorrhizal fungal species in both the sporocarp and ectomycorrhizal communities in the study plot. Four genets were identified from sporocarps and these coincided with those identified from ectomycorrhizas. Sporocarps of each S. pictus genet occurred separately from those of other genets. Spatial distributions of ectomycorrhizas of each genet were wider than those of sporocarps. The largest genet occupied c. 54% of the plot, and the area of each genet differed considerably. • Vegetative growth of mycelia is assumed to play a more important role in the propagation of S. pictus than colonization from spores because expansions of all the four genets ranged from 25 to 30 m and no small genets were found in this plot.