| A proteomic study,using 2-DE and MALDI-TOF-TOF,was conducted in sweet pepper fruit(cv.’hongfang’)during the storage of senescence.The sweet peppers were treated by different postharvest treatment,1-Methylcyclopropene(1-MCP)treatment group and 1-Methylcyclopropene combined with heat treatment(HM).The main research methods were the identification,functional and bioinformatics analysis of differently expressed proteins in order to further explain the regulation mechanisms of postharvest sweet pepper fruit during senescence.The main results are as follows:1.A two-dimensional electrophoresis system for total protein from sweet pepper fruits was established.The results showed that the best image of picture as indicated by protein spot uniformity and background clearness as well as protein point resolution was obtained at pH7.8 for extract buffer and by adopting phenol extraction method,loading 1200μg protein to 17cm IPG strip of pH 5～8 and isoelectric focusing at 66000VH followed by SDS-PAGE,and finally detecting proteins with coomassie brilliant blue G-250 staining.The total protein spots in the image of pictures were around 703±17.And most of relative molecular mass of protein spots were between 14.4 and 116.0 kDa.The established two-dimensional electrophoresis system could meet the needs of the subsequent mass spectrometry analysis.2.In order to advance the understanding of senescence regulation in post-harvest treatment of sweet pepper fruit(cv.’Hongfang’),the physiological and quality changes along with the proteomics were studied.The experimental groups were the 1-Methylcyclopropene(1-MCP)treatment group and 1-Methylcyclopropene combined with heat treatment(HM)group.We studied that the effects of HM treatment were different from 1-MCP treatment on involved protein profiles by a proteomic approach with 2-DE and MALDI-TOF/TOF,which would analyse the regulation mechanism on senescence of sweet pepper fruits by postharvest treatment through proteomics.Total protein was extracted by the phenol extraction method,and more than 500 spots were detected in each gel.According to PDQuest 8.0 software and Statistical Analysis,67 differentially expressed proteins(p ≥ 0.05)were identified using NCBInr-Capsicum annuum EST and placed into six categories by KEGG and PIR.The categories include metabolism(64%),genetic information and degradation(15%),environmental information processing(3%),cellular processes(6%),stress response and defense(12%),and unclassified(l%).Among the different proteins,metabolism related protein group was the largest,stress response and defense-related protein group was the second.And according the wolf psort,the proteins were identified in different subcellular organelles,such as cytoplasm,chloroplast,mitochondrion,peroxisome,cell wall,membrane and so on.The specific performance was that HM treatment protected fruit cells and delayed senescence by regulating multiple pathways:glycolysis and the citric acid cycle related proteins(glucose-6-phosphate isomerase,displacement 2,3-phosphatase,citrate synthase)were down regulated;ascorbate glutathione cycle related proteins(glutathione reductase,glutathione peroxidase,manganese superoxide dismutase,L-ascorbate peroxidase)and chlorophyll biosynthesis protein(8-aminolevulinic acid dehydratase)were up regulated;cellular processes related proteins were regulated up(α-1,4-glucan-synthase protein,actin-97,a-tubulin)or down(metacaspase 1).Besides,some other proteins were related to amino acid anabolic,membrane transport,and so on.They all involved in the regulation of sweet pepper fruit senescence.The study showed that HM treatment by regulating the associated proteins,slowing carbohydrate metabolism,maintaining a stable metabolism of oxygen free radicals,preserving cell life and delaying the fruits color turning,so as to achieve the purpose of delaying senescence.HM treatment compared with 1-MCP treatment was better in prolonging the fruit shelf life and maintaining the commodity. |
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