Proteomic analysis of changes in mitochondrial protein expression during peach fruit ripening and senescence

Ripening and senescence define the last step of fruit development, which directly affects its commercial value, and mitochondria play a crucial role in these processes. To better understand mitochondrial roles in maintaining and regulating metabolism in storage tissues, highly purified mitochondria were isolated from peach tissues (Prunus persica. cv. Xiahui-8) stored at 4°C and 25°C, respectively, and their proteome was conducted using the method of 2-DE and MALDI-TOF/TOF. Twenty-four (24) differentially expressed proteins (2-fold, p≤0.01) were identified out of more than 300 spots and were divided into six categories by PIR and Uniprot, including oxidative stress (34%), carbon metabolism (29%), respiratory chain (17%), amino acid metabolism and protein biosynthesis (8%), heat shock protein (4%), ion channels (4%). Proteins involved in antioxidative systems, gluconeogenesis, glycolysis, ethanol fermentation were changed significantly in response to high temperature. Storage at 4°C dramatically delayed ripening and senescence processes by postponing the climacteric peak, slowing down carbon metabolism and degradation of cell structure. Besides, low temperature induced the expression of formate dehydrogenase and some amino acid metabolism proteins. Proteins classified in respiratory chain, ion channels showed high coherence with climacteric respiratory burst, and the antioxidative enzymes showed relatively important symptoms on ROS scavenging through orderly expressions.

With the advent of proteomics and mass spectrometry (MS), it becomes possible to identify the specific functions of differentially abundant proteins in peach mitochondria. In the present study, a procedure to isolate mitochondria from peach fruits was established, and the mitochondrial proteome was systematically analyzed by 2-D gel electrophoresis procedures in combination with protein identification by mass spectrometry. Differentially expressed proteins in peach mitochondria during different stages of peach fruit ripening and senescence were characterized. Our data provide a great deal of information likely to enhance the understanding of the mitochondrial function in peach ripening and senescent process during storage.