Abstract
Rhizopogon roseolus, a hypogeous basidiomycete, also known as “shoro” in Japan, is an important ectomycorrhizal symbiont of the Pinaceae. Recent studies suggest that ectomycorrhizal fungi play an important role in the protection of host roots from environmental stressors such as heavy metals and excessive salt. However, there are no studies characterizing salt tolerant strains of R. roseolus in a soil substrate. Here, we used sandy soil from the wild to observe the growth of R. roseolus strains in soil, and analyzed the correlation of mycelial growth between soil substrate and agar medium. All the strains grew well in sandy soil without a host plant, and on the surface of the soil, several hyphae aggregated to form a mycelial colony. A significant positive correlation was observed between the mycelial growth of R. roseolus in soil and on agar. In saline culture, mycelial growth in soil with 100% of the salinity of seawater showed a positive correlation with mycelial growth on 100% seawater agar medium. These results suggest that mycelia of R. roseolus seem more sensitive to salt in soil than on agar, and sandy soil will be useful to characterize the salt tolerance of R. roseolus strains in soil substrates.
