Abstract
Rhizopogon roseolus is an ectomycorrhizal mushroom with a worldwide distribution. A recent study reported that a salt-tolerant strain could be produced by cross-breeding this mushroom. However, no studies on the selection of salt-tolerant strains by mutagenesis have been performed. Here, to induce mutations, we treated basidiospores of R. roseolus with ethyl methanesulfonate (EMS), a widely used chemical mutagen, and evaluated the salt tolerance of the recovered mutants. Out of 88 monosporous strains recovered from EMS-treated basidiospores, we selected 5 halophilic strains that showed vigorous mycelial growth on medium containing 300 mM NaCl. Three hybrid strains produced by crossing among halophilic monosporous strains also showed vigorous growth on medium containing 300 mM NaCl. To investigate stability of halophilic characteristics, subculturing was carried out for 6 months. After subculturing, halophilicity was recognized in 2 of the 3 hybrid strains. The 2 halophilic hybrid strains were considered suitable for environments containing NaCl.
