PRODUCTION OF ETHYLENE BY TISSUES OF TOMATO, PEPPER, FRENCH-BEAN AND CUCUMBER IN RESPONSE TO INFECTION BY BOTRYTIS-CINEREA

Ethylene production by detached leaves of tomato, pepper, bean and cucumber infected by Botrytis cinerea was much higher than that of noninfected leaves of the same hosts. Maximum production of ethylene was observed in leaves showing mild symptoms of the disease as compared with noninfected or completely infected leaves. The fungus produced negligible amounts of ethylene when grown on autoclaved leaves, with the exception of pepper leaves supplemented with methionine (0·14 nl g-1 h-1). Exogenously supplied ethylene induced 75-370% more necrosis than B. cinerea infections in all the crops. Applications of methionine increased necrosis to a lesser extent. Silver-thiosulphate (STS) at levels of 10-4 and 10-5m, aminooxyacetic acid (AOA 10-3 and 10-4 m) and aminoethoxyvinylglycine (AVG 10-3 and 10-4 m) reduced the development of grey mould disease significantly. AOA and AVG inhibited the production of ethylene by all the crops. Disease incidence in cucumber fruits was increased by growth at 4 °C or treatment with ethephon prior to inoculation whereas STS treatments completely inhibited disease development. Disease development was also decreased in intact plants treated with the inhibitors. © 1990.