Production of extracellular enzymes by germinating cysts of Phytophthora infestans

Abstract

Cysts of Phytophthora infestans were prepared and allowed to germinate in water for 0 to 20 h. The activities of 11 different types of hydrolytic enzymes were detected in the extracellular germination medium. A time-course study revealed that most of the enzyme activities increased very little during germination. However, esterase activity increased 45-fold during germination. The rate of appearance of esterase activity closely paralleled the rate of germ tube growth. The intracellular levels of esterase activity were low throughout germination. These observations suggest that esterase is secreted during germination. Cysts also were allowed to germinate in the presence of various potential metabolic inhibitors and their effect on the appearance of esterase activity and on germ tube growth was measured. With each compound that inhibited the rate of germ tube growth, there was a nearly proportionate inhibition in the rate of appearance of extracellular esterase.