EFFECTS OF EXOGENOUS NO ON ASA-GSH CIRCULATION METABOLISM IN YOUNG LOQUAT FRUIT MITOCHONDRIA UNDER LOW TEMPERATURE STRESS

Abstract

The effects of exogenous nitric oxide (NO) on antioxidant systems under low temperature stress in young loquat (Eriobotrya japonica Lindl. cv. Jiefangzhong) fruit mitochondria were investigated in this study. Young loquat fruits were treated with 0.2, 0.5 and 1.0 mmol L-1 of sodium nitro-prusside (SNP) under 0°C for 6-hours. The results indicated that the concentrations of hydrogen peroxide (H2O2) was lower than the control following treatment. However, reduced glutathione (GSH) and ascorbate (AsA) concentrations resulted in increased 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) activity relative to the control (p<0.05). Therefore, we concluded that suitable exogenous NO concentration enhanced the mitochondrial antioxidant capacity in young loquat fruits by increasing GSH and AsA concentrations, elevating APX, GR, DHAR and MDHAR activity, and reducing H2O2 concentration. As a result, oxidative damage was reduced and the cold-resistance capacity of young loquat fruits was increased under low temperature stress conditions.