The Proteomics Research Of Cucumber Phloem Under Salt Stress

In order to research the proteome of cucumber phloem percolate under salt stress environment, thesalt-sensitive cucumber cultivars,‘Jinyou No.1’ and ‘Xintai mici’ were treated by growing in nutrientsolution containing75mM NaCl. After3-day-treatment, we collected the liquid of cucumber phloem.First of all, in order to ensure the next experiment we detected the protein purity by SDS-PAGEelectrophoresis. In addition, through the iTRAQ quantitative analysis, we identified the biologicalcharacteristics of proteins extracted from the liquid of cucumber phloem and obtained which wereverified on mRNA level. Meanwhile, we analyzed, at different salt-treatment timing, the genesexpressions of those specific proteins in leaf and root by Fluorogenic Quantitative PCR. Main resultswere as follows:1. The result of SDS-PAGE electrophoresis indicated the protein purity of the liquid extracted fromcucumber phloem using the cutting seeping method was high, which was exactly up to standard ofiTRAQ quantitative analysis experiment. We identified745kinds of proteins in which69specificproteins were found in ‘Jinyou No.1’ and65were detected in ‘Xintai mici’ under salt treatment. Inthese differently expressed proteins, there were only4up-regulated and16down-regulated proteinswere in common, and the rest of them were particular to different cucumber cultivars. The functionalclassification of the proteins showed28proteins were related to metabolism,17proteins had somethingto do with protein trafficking,7proteins were in connection with energy and protein movement,24proteins were allied to stress and defense,8proteins were related to plant growth and development,13proteins involved in signal transduction and transcriptional regulation, and the rest proteins belonged toimpurity proteins.2. We declared, through researching the gene expressions of response proteins in the liquid extractedfrom cucumber phloem by Real-time quantitative PCR, the mRNA and proteins expression tendenciesof the same9proteins, which accounted for67%and45%in ‘Jinyou No.1’ and ‘Xintai Mici’respectively, were in common. The protein expressions of Cs5, Cs6, Cs7in ‘Jinyou No.1’ under salttreatment were up-regulated, which was opposite to the regulated condition of the mRNA expressions.The proteins and mRNA expression levels of Cs7in ‘Xintai Mici’ were on the contrary. The mRNAexpression tendencies of Cs2, Cs5and Cs6protein were not significant, but the protein levels was significantly different. After the study on the proteins and genes expression, we found salt treatmentcould induce the expressions of salt-responsed proteins in cucumber root and leaf.