The involvement of ethylene in wound-induced suberization of potato tuber (Solanum tuberosum L.):: a critical assessment

The determination of hormonal requirements for wound-induced suberization is important in developing new approaches and future postharvest technologies to control various wound-related disease and defect problems in potato tuber (Solanum tuberosum L.). Although. the hormone ethylene has been shown to be involved in various kinds of plant stress, including certain wound responses, its role in suberization had not been determined. The role of ethylene in wound-induced suberization of potato tuber was examined over a 9-day wound-healing period, using a variety of ethylene biosynthesis and action inhibitors. Ethylene evolution was stimulated by wounding and reached a maximum 2-3 days after tuber wounding, and then gradually declined. The competitive inhibitor of ethylene action, 2,5-norbornadiene, had no effect on the wound-induced accumulation of suberin polyphenolic(s) (SPP). Similarly, the ethylene antagonist 1-methylcyclopropene (1-MCP) had no apparent effect on wound-induced accumulation of SPPs or on the accumulation of suberin polyaliphatic(s) (SPA). Treatment of tubers with ethylene, applied either before or after wounding, had no effect on the induction or accumulation of either suberin biopolymer. Treatment with the ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG), inhibited wound-induced ethylene production by ca. 90%, but did not affect wound-induced suberization. Collectively, these results indicate that, although increased ethylene evolution is part of the tuber wound response, ethylene is not required for wound-induced suberization of the closing layer (suberization of existing cells at the wound surface) during the first 2-4 days of wound-healing or subsequent suberization of phellem cells (between 4 and 9 days) created by the wound-induced formation of the phellogen. These results are important in determining the mechanisms regulating suberization and in assuring that wound-induced suberization is not inhibited with the application of new technologies that effectively control various ethylene mediated processes in vegetables and fruit. Published by Elsevier B.V.