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 P. nicotianae var. parasitica. Higher constitutive chitinase, b-1.4-glucanase and peroxidase activities were detected in uninoculated leaves and cell cultures of the resistant line.Postinfectional variations in leaves were related to symptom severity rather than varietal or non-host resistance to the phytophthora spp. In cell suspension, inoculation with both fungi induced an early and transient increase of phenylalanine ammonia-lyase (PAL) and b-d-glucosidase. PAL and b-d-glucosidase variations appear to be suitable post-infectional markers of varietal resistance to P. capsici in pepper cell cultures but not in leaves.