FIG 5.

Disruption of single MAT genes in heterothallic strains revealed their roles in mating and sporulation. (A) Mating and sporulation phenotypes of combinations of all dic1-2Δ single MAT gene disruption strains. Mating was not possible in any of the crosses with mata2Δ(a) and matα1Δ(α) cells, confirming the essential roles of Mata2 and Matα1 in diploid cell formation. Disruption of MATa1 in a-type cells or MATα2 in α-type cells resulted in a sporulation defect in diploid cells [reduced mating efficiency in mata1Δ(a)/mata2Δ(α) cells]. (B) Mating and sporulation phenotypes of dic1-2Δ single MAT mutants crossed with the unmodified dic1-2Δ strain of opposite mating type. (C) Bright-field microscopy images of diploid MAT mutant cells with stable mating types under sporulation conditions. Wild-type-like tetrads were formed by cells carrying the mutated genes in the silent MAT locus (inside the orange box). No mature spores could be observed in diploid mata1Δ(a) and matα2Δ(α) cells [only little spore formation in mata1Δ(a)/mata2Δ(α) cells]. The arrows indicate shmoo formation. Bars, 5 μm.