Effect of Exogenous γ-Aminobutyric Acid Treatment on Proline Accumulation and Chilling Injury in Peach Fruit after Long-Term Cold Storage

The effect of exogenous gamma-arninobutyric acid (GABA) on chilling injury of peach fruit was investigated. Freshly harvested peaches were treated with 1, 5, or 10 mM GABA at 20 degrees C for 10 min and then stored at 1 degrees C for up to 5 weeks. The results showed that all of the GABA treatments could reduce chilling injury of peach fruit with 5 mM being the most effective concentration. GABA treatment significantly enhanced the accumulation of endogenous GABA and proline, which resulted from the increased activities of glutamate decarboxylase, Delta(1)-pyrroline-5-carboxylate synthetase, and omithine delta-aminotransferase and decreased proline dehydrogenase activity. Our results revealed that GABA treatment may be a useful technique to alleviate chilling injury in cold-stored peach fruit, and the reduction in chilling by GABA may be due to the induction of endogenous GABA and proline accumulation. These data are the first evidence that exogenous GABA induced chilling tolerance in postharvest horticultural products.