Effects of high temperature on physiological processes leading to sexual reproduction in Phytophthora parasitica

Sensitivities of various physiological processes to elevated temperature were investigated to determine the mechanisms of inhibition of oospore production by high temperature in Phytophthora. The production of α hormones and their receptors by A 1 and A 2 isolates of Phytophthora parasitica was inhibited at high temperature. However, after being produced, α hormones and their receptors were stable at high temperature. No oospores were produced when A 1 and A 2 cultures were exposed to high temperature during hormone reception or oospore formation after hormone induction. Results suggest that the inhibition by high temperature of sexual reproduction in P. parasitica was through inhibition of hormone production, hormone reception, receptor formation, and oospore formation after hormone induction of sexual reproduction.