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 l ignin and monitoring the activities of key enzymes involved in the lignific ation process. There was a 40% reduction in lignin biosynthesis during woun d healing in response to gamma irradiation. The level of the first enzyme i nvolved in lignin biosynthesis, phenylalanine ammonia lyase (PAL), was five -fold higher in irradiated potatoes than in control tubers during wound hea ling. However the level of another key enzyme, cinnamyl alcohol dehydrogena se (CAD) was found to be 30% less in irradiated potatoes. There was no sign ificant change in peroxidase activity and its isozyme pattern during wound healing. Differential regulation of different enzymes of lignin biosynthesi s in response to gamma irradiation may be responsible for the decreased lig nin biosynthesis. (C) 2000 Elsevier Science B.V. All rights reserved.