MATERIALS AND METHODS
Fungal isolates. Nineteen wild dikaryotic isolates of R. roseolus were used in this study (Table
1). The isolates have been deposited in the culture collection of the Fungus/Mushroom Resource and Research Center, Faculty of Agriculture, Tottori University, Japan. To prepare inoculum, the isolate was inoculated on malt extract agar (20 g malt extract (Oriental Yeast Co., Ltd., Tokyo, Japan), 20 g agar, and 1 L tap water) plates and incubated for 3 wk at 25 °C in the dark. After incubation, 5 mm square mycelial agar plugs were removed by a surgical knife and used for inoculation.