Reversible and Irreversible Reduction of ACC-dependent Ethylene Formation in Mung Bean (Vigna radiataL Wilczek) Hypocotyls Caused by Chilling1

摘要

Etiolated seedlings of mung bean (Vigna radiata[L] Wilczek) grown at 26°C in the dark were chilled at 0°C for various periods and then returned to 26°C to follow the development of chilling injury and changes in ACC-dependent ethylene-forming activity (EFA). After chilling for one day, they could grow normally at 26°C, but not after chilling for more than two days. The longer chilling caused a remarkable increase in electrolyte leakage from the hypocotyl tissues, suggesting plasma membrane injury. The ACC-dependent EFA in vivo in hypocotyls was found to be sensitive to chilling and progressively declined as a function of the chilling period. After 1-day chilling, the activity declined to less than 50 per cent of the unchilled tissues, but it returned to the normal level within 3 h after the return to 26°C. However, chilling more than two days caused irreversible loss of the activity. Thus, there seems to be an intimate relationship between irreversible loss of the EFA and chilling injury of the tissues. The recovery of EFA after chilling for one day could be markedly inhibited by cycloheximide and monensin, suggesting that the recovery requires protein synthesis and, presumably, includes repair of partially injured cellular membranes, mediated through the Golgi appar