A compatible pheromone–receptor pair from Schizophyllum elicits cell-cycle arrest and mating. (A) Cell-cycle arrest in response to pheromone was tested by the halo assay. Master plates with duplicate patches of MATa cells (W303–1A) containing either the control vector pPGK (upper two patches in each panel) or pPGK-bbp2(4) (lower two patches) were replica plated on MATα lawns to test growth arrest by secreted pheromone. The lawns used to test response were STE3 sst2 (Tn44–1B) containing pPGK (left panel), ste3 sst2 (SDK47) containing pPGK (middle panel), and ste3 sst2 (SDK47) containing pPGK-bbr1. (B) Mating tests were performed between MATa and MATα cells by pairing complementing auxotrophs (his4 versus his3) and assaying for growth of diploids on SD(his−) medium. Rows: the MATa MFA1 MFA2 strain (SM1058) containing pPGK (top), the MATa mfa1 mfa2 strain (SM2331) containing pPGK (middle), and the MATa mfa1 mfa2 strain containing pPGK-bbp2(4). Columns: The MATα STE3 strain (Tn44–1B) containing pPGK (left), the MATα ste3 strain (SDK47) containing pPGK (middle), the MATα ste3 strain (SDK47) containing pPGK-bbr1 (right).