Diploid strains were pre-grown overnight at 30 °c on a 2% YPDA plate and then inoculated onto the sporulation plate. After 48 h of incubation, the cells were treated with zymolyase solution (0. 3 mg/ml Zymolyase 20t (Seikagaku Co., Tokyo, Japan) and 0. 015 M phosphate bufrer, PH 7. 5) for 20 min at 30 °c. Afrer the cells were plated onto 2% YPD (PH 5. 5), tetrads were split into 4 individual spores with the Singer MSM System 300 (singer Instrument Co. Ltd., Watchet, Somerset, UK). The plate was incubated at 30 ° C.