Wound-induced shikimate dehydrogenase and peroxidase related to lignification in pepper (Capsicum annuum L.) leaves

Wounding on non-excised Capsicum annuum leaves, maintained on the whole growing plant, causes an increase in shikimate dehydrogenase (SKDH, EC 1.1.1.25) and peroxidase (EC 1.11.1.7) activity. The observed induction of both enzymatic activities was related to lignin accumulation, and in the case of peroxidase, it was located in the vicinity of the wounds. However, wounding did not cause changes in soluble phenolic compounds. PAGE analysis showed that the shikimate dehydrogenase pattern was the same in both control and wounded leaves, but each isozyme was enhanced to a different degree: SKDH-1 = SKDH-2 > SKDH-5 > SKDH-4 > SKDH-3. The relationship between the degree of induction and both subcellular location and biosynthetic function is proposed. In the case of peroxidases, one new acidic isozyme (PRX-A2, pI 4.5) was detected by isoelectric focusing in wounded leaves, and another one (PRX-A4, pI 3.7) was enhanced more than 8 times with respect to control leaves. The possible role of these isozymes in lignin biosynthesis and wound healing is discussed.