S-Carvone Inhibits Phenylalanine Ammonia Lyase (PAL) Activity and Suberization During Wound Healing of Potato Tubers

Abstract

Summary The periderm formation of wound tissue of potato tuber was inhibited temporarily after exposure to S-carvone. In wound tissue of control tubers a suberized cell layer was visible after 4 days whereas in S-carvone treated tissue this was observed only after 14 days in most of the tubers. At day 21 all the S-carvone treated tubers had formed suberin but only 10 % of the tubers had developed a (begin of a) cambium layer. The appearance of suberin was related to the activity of phenylalanine ammonia lyase (PAL); in control and S-carvone treated tissue, maximum PAL activity preceded the appareance of the first suberized cell layers by 2 and 5 days, respectively. The specific activity reached the same level in both control and S-carvone treated wound tissue. A short term treatment (2, 4 and 7 days) of tuber wound tissue with S-carvone delayed suberin formation. All the treated tubers showed suberization about 4 days after removal of S-carvone and this was closely related to the increase in PAL-activity. After the S-carvone treatment, the glutathione metabolism increased: after an initial decrease, as observed in the control, the total glutathione content increased fourfold after 9 days and remained high during the treatment. However, the length of the wound healing period before the start of a S-carvone treatment was of great influence on the increase of the glutathione metabolism and on the induction of glutathione reductase.