Reduced chilling injury in mango fruit by 2,4-dichlorophenoxyacetic acid and the antioxidant response

The aim of this study was to evaluate the effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on chilling injury (CI) in mango fruit. 2,4-D treatment at 150 mg L-1 could significantly alleviate CI or disease incidence of mango fruit during 7 days storage at 4 degrees C and an additional 14 days at 20 degrees C (P < 0.05). Fruit quality, including increased soluble solids, soluble sugar, fruit firmness, and peel chlorophyll level, was strongly improved by 2,4-D treatment. These results indicate that 2,4-D could be used as an effective method to preserve the postharvest life of mango fruit. Endogenous H2O2 levels in the fruit were increased by 2,4-D treatment and decreased by exogenous H2O2 treatment. The activities of catalase, superoxide dismutase, ascorbate peroxidase (APX) and glutathione reductase (GR) in the 2,4-D-treated fruit were much higher than those in control fruit. However, exogenous H2O2-treated fruit showed higher CI and lower activities of APX and GR. In addition, the results showed that 2,4-D treatment could significantly enhance levels of the endogenous ABA and GA(3), and reduce IAA and zeatin riboside levels in the fruit. These results suggest that 2,4-D could regulate chilling resistance by changing the balance of endogenous hormones levels. (C) 2007 Elsevier B.V. All rights reserved.