Marco, S., Agricultural Research Organization, The Yolcani Center, Bet Dagan 50-200, Israel
Levy, D., Agricultural Research Organization, The Yolcani Center, Bet Dagan 50-200, Israel

Infection of cucumber seedlings by cucumber mosaic virus (CMV) caused a significant reduction in the chlorophyll content of cotyledons corresponding with the appearance of chlorotic lesions. This reduction was associated with a significant increase in ethylene production in the CMV-infected cotyledons. Exogenous treatments of infected and virus-free cucumbers with ethylene or ethephon resulted in a significant reduction in the chlorophyll content of cotyledons. Suppression of endogenous ethylene activity by CO2 treatment, or ethylene removal with either KMnO4 or by sub-atmospheric pressures, delayed chlorotic lesion development. Thus, without ruling out other factors, the possibility of the involvement of ethylene in CMV-induced chlorotic lesion development is suggested and discussed. © 1979.