Study On Effects And Mechanicsms Of Proline On Alleviating Chilling Injury Of Peach Fruit

Peach fruit is an important fruit in China, and is popular for its juicy texture, delicious flavor, beautiful color and nutrient-richness. However, Peaches are matured in mid-summer, and they are strong respiration after harvest. In addition, they are susceptible to pathogenic infection and physiological deterioration during ambient temperature storage and ripening, so it’s difficult to extent its postharvest life. It should be pointed out that cold storage is effectively used to control postharvest disease and inhibit ripening of peach fruit. Because of cold-sensitive fruits, they are easy to have chilling injury, thus affecting the value of the goods. Consequently, study peach fruit cold damage control technology is the key to a solution to the storage and transport of peach fruit. In this paper, the effects of exogenous proline on CI in peach fruit(Prunus persica L.Batsch cv. Baifeng) and the possible mechanisms involved were investigated. The results were as follows:1. Effects of harvest maturity on chilling injury and proline accumulation of juice peach fruit during low temperature storage.The fruits of juicy peaches ’Baifeng’ were directly used to be in cold storage. The results reflect that the fruits with7-8maturity-degree at5℃have the ability to soften with a decrease in firmness and an increase in juice rate, as compared with the fruit with9maturity-degree. Meanwhile, the fruits with7-8maturity-degree have high levels of proline and GAB A content, an increase in activities of OAT and GAD and a decrease in activity of GAD.2. Effects of exogenous application of proline on chilling injury in postharvest peach fruit after low temperature storagePeach fruit were pretreated with different concentrations of praline (0.0(control),1mM,5mM,10mM) for10min and then stored for35d at1℃to investigate the effect of proline treatment on chilling tolerance. In present study, treatment of peach fruit with proline resulted in significantly lower chilling injury index, especially5mM proline. Our experiment suggested that exogenous proline treatment was beneficial for accumulation of proline and y-aminobutyric acid (GABA) due to increased P5CS, OAT and GAD and decreased PDH activities. Overall, our results indicated that accumulation in endogenous proline and GABA contents appears to have a strong connection with improvement ability to enhance the chilling tolerance of peach fruit after harvest.3. The possible mechanisms that proline treatment alleviating chilling injuryPeaches treated with5mM proline were chosen to investigate the possible mechanisms involved in alleviating CI. The results showed that this treatment effectively maintained the activities of GR, MDHAR, APX, GST, SOD and the level of GSH and AsA content, which reduced the accumulation ROS. It is helpful to slow down the injury of the system of membrane, even the occurrence of CI.