Abstract:

The paper studied the application of reduced glutathione(GSH) in increasing the chilling resistance of young loquat(Eriobotrya japonica cv. Zaozhong No.6) fruits. The container seedling of three-year-old loquat were treated with 100, 300 and 500 mg·L^-1 of GSH to investigate the effects of exogenous GSH on AsA-GSH circulation metabolism in chloroplasts of young loquat fruits under low temperature stress, and its effects on the resistance to low temperature stress. The results showed that the contents of reduced glutathione(GSH) and ascorbic acid(AsA) in chloroplasts decreased and the activities of ascorbate peroxidase(APX, EC 1.11.1.11), glutathione reductase(GR, EC 1.6.4.2), dehydroascorbate reductase(DHAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) were also inhibited decreased when the young loquat fruits were under low temperature stress. The treatment with 100 mg·L^-1 of GSH on young loquat fruits could significantly increase the GSH, AsA contents and APX, GR, MDHAR activities. Furthermore, the treatment promoted AsA-GSH circulation metabolism, and improved the ability of free radicals to scavenge in chloroplasts. The results demonstrated that exogenous GSH played a role in the low temperature stress resistance of young loquat fruits.

Key words: chloroplast, reduced glutathione (GSH), low temperature strees, AsA-GSH circulation metabolism