Differential induction of superoxide dismutase in Coffea arabica-Hemileia vastatrix interactions.

Coffee – rust interactions are governed by the gene-for-gene relationship, the resistance of coffee plants characterized by rapid plant cell death (hypersensitive reaction – HR). Previous cytological studies using scavengers of active oxygen species, showed that the superoxide dismutase (SOD) significantly inhibited the cell death, suggesting the involvement of the anion radical O2 in the HR. This work aims to understand the role of SOD in coffee resistance. Differential induction of superoxide dismutase (SOD) was observed in compatible and incompatible Coffea arabicaHemileia vastatrix interactions. In the incompatible interaction a peak of SOD activity was detected around 17-24 hours after inoculation, prior to cell death observation. On the contrary, in the compatible interaction no significant changes in SOD activity was observed at this early stage of the infection process. Native PAGE analysis showed at least six isoenzymes of SOD, tree of which were CuZn-SOD, one was Mn-SOD and two Fe-SOD. The isoenzyme pattern of SOD obtained by IEF showed at least three groups of SOD isoenzymes with a pI of 5.4, 4.9 and 4.7 respectively. The involvement of SOD in coffee-rust interactions will be discussed.