STIMULATION OF LIPOXYGENASE ACTIVITY IN COTYLEDONARY LEAVES OF COFFEE REACTING HYPERSENSITIVELY TO THE COFFEE LEAF RUST

Lipoxygenase activity was followed in cotyledonary leaves of coffee cultivars resistant and susceptible to the coffee leaf rust (Hemileia vastatrix). A rise in lipoxygenase activity was observed during the incompatible interaction, whereas the activity of the enzyme remained fairly constant in the compatible coffee-coffee rust combination. The increase in lipoxygenase activity was accompanied by the development of the hypersensitive reaction as followed by fluorescence microscopy. An elicitor preparation from germ tubes of coffee leaf rust, when injected into the cotyledons, also stimulated a rise in lipoxygenase activity in both the resistant and in the susceptible cultivars. Our results suggest an involvement of lipoxygenase activity in the expression of the hypersensitive reaction in cultivars of coffee resistant to coffee leaf rust. © 1993 Academic Press, Inc.