| Peach (Prunus persica L.) is a climacteric fruit and the ripening process is triggered and driven by ethylene. A number of ripening-related genes are recruited to express differentially during this process leading to considerable changes in texture, pigmentation, taste and aroma. This is responsible for its short shelf-life of less than7days at ambient temperature and need to take measures for its efficient handling and transportation. We have been interested in the identification and functional analysis of differently expressed proteins during peach fruit ripening as well as their regulation by hot water and1-MCP treatments. Thus, we used2-DE followed by MALDI-TOF/TOF to investigate and analyze the biological function of the differently expressed proteins between hot water (48℃for10min) and/or1-MCP (10uL.L-112h) treated and control peach fruit (cv. huiyulu) during ripening and senescence in order to further explain the molecular mechanism of the biological process at proteomic level. The main results are as follows:1. The extracted proteins from the heat-treated peach fruit (dipped in hot water at48℃for10min and then stored at room temperature for up to5days) were used for proteomic analysis in order to understand the response of post-harvest peach fruit to heat treatment during ripening stage at proteomic level. After two dimensional gels electrophoresis (2-DE) was conducted, more than600protein spots were detected. Among them,35differently expressed spots (P<0.05) were selected to be excised and analyzed using MALDI-TOF/TOF, and finally30protein spots were confidently identified according to NCBI database. The results demonstrated that among the thirty protein spots expressed particularly induced by heat treatment,43.29%were related to stress response,16.78%to cell structure,13.09%to protein fate,6.71%to glycolytic pathway,3.36%to ripening and senescence and16.78%to unclassified. All of them are involved in the regulation of peach fruit development and ripening. All these indicated that the self-defense capability of peach fruit was improved by heat treatment. The study will enable future detailed investigation of gene expression and function linked with peach fruit ripening.2. A proteomic approach based on2-DE and MALDI-TOF-TOF techniques has been used in this work to study the effect of1-Methylcyclopropene (1-MCP) and2-chloroethylphosphonic acid (ethephon) on the protein profiles of melting peach fruit (cv. Huiyulu) during ripening. The extracted proteins from the1-MCP-treated and ethephon-treated peach fruit were used. More than600protein spots were detected by means of2-DE and38differently expressed spots (P<0.05) were selected to be excised and analyzed using MALDI-TOF/TOF, and35were finally confidently identified according to the peach EST database downloaded from Genome Database for Rosaceae and NCBI database. Among the35successfully identified protein regulated by1-MCP and ethephon,26proteins were modulated by1-MCP, including9up-regulated proteins and17proteins were down-regulated.27proteins were regulated by ethephon, including12up-regulated protein and15down-regulated proteins. Meanwhile,8proteins were down-regulated by1-MCP and up-regulated by ethephon, and5proteins down-regulated by ethephon but up-regulated by1-MCP. In addition, it was found that3proteins were depressed by both1-MCP and ethephon. Differently expressed proteins belonged to different metabolic pathways including energy and metabolism (34.29%including17.14%energy,5.71%carbohydrate metabolism,5.71%nucleotide metabolism and5.71%amino acid metabolism), cell structure (22.83%including14.29%cell fate and8.57%cytoskeleton reorganization), protein fate (17.14%including8.57%protein synthesis,5.71%protein modification and5.71%protein with binding function), stress response and defense (14.29%) and ripening and senescence (8.57%). All these indicated that the regulation patterns by1-MCP and ethephon at proteomic level are complicated, involving various metabolic pathways. The present study will be informative for exploring the exact roles of ethylene in peach fruit ripening and explaining the molecular mechanism of peach ripening.3. The peach fruit were treated with hot water (48℃for10min) combined with1-MCP (10uL.L-112h), and stored at room temperature for0,1,3and5days. After2-DE and MALDI-TOF-TOF,42spots were expressed differently and sussesfully identified between hot water and1-MCP treated and control fruit, the proteins were classified as five clusters, stress reponse and defense (35.71%), energy and metabolism (30.95%), ripening and senescence (14.29%), cell structure (14.29%) and protein fate (4.74%). According to PSORT (http://wolfpsort.org/) software, the protein were predicted in subcellular localization, and the results showed that21proteins were located in cytoplasmic,8in chloroplast and8in mitochondrial,1in endoplasmic reticulum and1in inner membrane. The results in the present work showed that hot water combined with1-MCP treatment could strength the ability of stress response and defense, inhibit the energy and metabolism, suppress the loss of Ca ion in cell and induce the expression of HSP and chapnion to improve self capability of defense. Taken together, the metabolic pathways mentioned above may partly explain why heat and1-MCP treatment could improve the fruit quality and extend the shelf life of peach fruit. |
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