ISOENZYME PATTERN OF SUPEROXIDE-DISMUTASE IN COFFEE LEAVES FROM CULTIVARS SUSCEPTIBLE AND RESISTANT TO THE RUST HEMILEIA-VASTATRIX

Superoxide dismutases (SOD; EC 1.15.1.1) in coffee leaves (Coffea arabica L.) from cultivars susceptible and resistant to infection by Hemileia vastatrix (Berk and Br.) were characterized by non-denaturing polyacrylamide gel electrophoresis. The 3 molecular forms of SOD were distinguished from each other by their different sensitivities to cyanide and H2O2. In leaves of the susceptible cultivar (cv. Caturra), one Mn-SOD, one Fe-SOD, and one Cu,Zn-SOD were found, and Fe-SOD was the most abundant isozyme (about 50 % of the total SOD activity). In coffee leaves from the resistant cultivar (cv. Colombia), two additional Cu,Zn-SODs were present. The appearance of new Cu,Zn-SOD isoenzymes could be related to the manifestation of resistance against fungal infection. The identification of Fe-SOD in a species belonging to the plant family Rubiaceae extends the small number of higher plants where the presence of these Fe-containing metalloenzymes has been demonstrated. Results obtained may be useful from an evolutionary viewpoint and also in oxy-radical studies in plants dealing with defence mechanisms against fungal infection.