Lignin biosynthesis during wound healing of potato tubers in response to gamma irradiation

The effect of gamma irradiation on lignin biosynthesis during wound healing in potato tubers was studied by [U-14C] phenylalanine incorporation into lignin and monitoring the activities of key enzymes involved in the lignification process. There was a 40% reduction in lignin biosynthesis during wound healing in response to gamma irradiation. The level of the first enzyme involved in lignin biosynthesis, phenylalanine ammonia lyase (PAL), was five-fold higher in irradiated potatoes than in control tubers during wound healing. However the level of another key enzyme, cinnamyl alcohol dehydrogenase (CAD) was found to be 30% less in irradiated potatoes. There was no significant change in peroxidase activity and its isozyme pattern during wound healing. Differential regulation of different enzymes of lignin biosynthesis in response to gamma irradiation may be responsible for the decreased lignin biosynthesis. (C) 2000 Elsevier Science B.V. All rights reserved.