VARIATION IN ENZYME-ACTIVITIES IN LEAVES AND CELL-SUSPENSIONS AS MARKERS OF INCOMPATIBILITY IN DIFFERENT PHYTOPHTHORA PEPPER INTERACTIONS

Activities of a pool of enzymes were compared in leaves and cell suspensions of two near-isogenic lines of pepper, susceptible and resistant to Phytophthora capsici, inoculated with the pathogen and with P. nicotianae var. parasitica. Higher constitutive chitinase, beta-1,3-glucanase and peroxidase activities were detected in uninoculated leaves and cell cultures of the resistant line. Post-infectional variations in leaves were related to symptom severity rather than varietal or non-host resistance to the Phytophthora spp. In cell suspensions, inoculation with both fungi induced an early and transient increase of phenylalanine ammonia-lyase (PAL) and beta-D-glucosidase activities in the resistant line only; cell cultures, however, did not discriminate between P. capsici and P. parasitica. PAL and beta-n-glucosidase variations appear to be suitable post-infectional markers of varietal resistance to P. capsici in pepper cell cultures bur not in leaves.