SENSITIVITY OF COCA (ERYTHROXYLUM-COCA VAR. COCA) TO ETHYLENE AND FUNGAL PROTEINS

Leaves of coca are the primary source of cocaine, There is interest in using Fusarium oxysporum as a mycoherbicide in addition to other meas ures to control coca production, but information on coca physiology, i ncluding the stress responses of coca leaves, is limited. Deleafing co ca plants stimulates rapid production of new leaves, and young expandi ng leaves readily abscise if treated with ethylene. Commercial prepara tions of cell wall degrading enzymes, as well as a 24-kDa elicitor fro m Fusarium oxysporum, induced significant levels of ethylene productio n by coca leaves. Ethylene pretreatment of coca leaves enhanced the pr oduction of ethylene by coca leaves in response to the cell wall degra ding enzyme preparation, Driselase, and the 24-kDa elicitor. However, ethylene pretreatment did nor enhance the rate of necrosis induced in response to either Driselase or purified 24-kDa elicitor. Driselase fa iled to elicit levels of necrosis comparable to the 24-kDa elicitor ev en at 30-fold higher protein concentrations. Tile response of coca lea ves to the 24-kDa elicitor saturated at 6.7 mu g ml(-1). Age of coca l eaves influenced both the level of resulting necrosis and the amount o f ethylene produced in response to protein. Very young leaves produced the highest levels of ethylene and necrosis in response to Driselase and the 24-kDa elicitor. The data suggest that responsiveness of coca leaves to control measures may be synchronized over the first few week s following defoliation.