The C. luttrellii homothallic MAT gene alone confers on heterothallic C. heterostrophus the ability to self and cross. (Top) Plate with a senescent corn leaf as substrate for mating (18) inoculated with C. heterostrophus carrying the fused C. luttrellii MAT gene. Black bodies (arrowhead) are pseudothecia, indicating selfing. (Middle) Part of a mating plate, inoculated first with an albino C. heterostrophus MAT-1 tester strain, followed by inoculum (black rectangle) of a pigmented C. heterostrophus MAT-deletion strain carrying the fused C. luttrellii MAT gene. White pseudothecia (arrowhead) indicate crossing with the albino parent as female, because pseudothecial walls are of maternal origin. (Bottom Left) Progeny of a selfed transformant (Top), demonstrating that pseudothecia from selfed strains yield viable ascospores and that all progeny of a selfed pigmented strain are pigmented. (Bottom Right) Progeny of a cross (Middle), demonstrating that ascospores are viable and that alleles at the color marker Alb1 segregate (1:1).