Figure 2.

Tetrad analysis to demonstrate the inheritance of the suppressor of sterility 1 (sos1) in S. macrospora. Sterile (ΔSmkin3^sos1−, color code yellow) or fertile (ΔSmkin3^sos1+, color code orange) deletion strains lacking Smkin3 were crossed with wild-type (wt) strains carrying different alleles of sos1 (S70823 wt^sos1+, color code blue and S147487 wt^sos1−, color code green). In all strains, we have neglected the fus1-1 mutation since it is only a marker to recognize recombinant asci during ascospore isolation. Ascus type designation: P, parental; T, tetratype; R, recombinant; and nd, not determined due to a reduced spore germination. Phenotype designation: hyg^rS, hygromycin B-resistant, sterile (ΔSmkin3^sos1−); hyg^rF, hygromycin B-resistant, fertile (ΔSmkin3^sos1+); and hyg^sF, hygromycin B-sensitive, fertile (wt^sos1− and wt^sos1+). Hyg^sS strains, which would indicate sterile wt strains, were never observed.