FIG. 5.

Mutants deficient in ras2 are unable to form aerial hyphae. A strong mating reaction was seen when compatible wild-type strains were cospotted on charcoal-containing medium (top left). A strong mating reaction was also observed when wild-type cells were coinoculated with ras2 mutants (top right and middle left). Coinoculation of compatible ras2 mutants resulted in a yeastlike colony (middle right). P6D cells are capable of producing aerial hyphae when inoculated without a mating partner (bottom left), but P6D cells defective in ras2 are not able to produce these hyphae (bottom right).