Study On Protein Differential Expression Of Radicle And Hypocotyl In Soybean Seeds With Various Vigors

In this study, soybean seed “zhongdou27” with moisture content of14%was used as experimentalmaterial. The material was artificially aged at40℃for8d,12d and20d，soybean seed germinationpercentage of98%dropped to85%,50%and5%respectively. The proteomic changes of radical andhypocotyl in seeds with various vigors were studied through2-DE and MALDI-TOF-TOF MS. Weaimed to analyze the differences responsing to stress between radical and hypocotyl, and then furtherunderstand molecular mechanism of seed aging, at the same time, to provide theoretical basis for thesafe conservation of crop germplasm resources. The main results are as follows:1. There were some differences in expression patterns of differentially expressed proteins in radicleand hypocotyl. In total of35protein spots were analyzed in radicle, of which20protein spots weredown-regulated,4protein spots were up-regulated,11protein spots were firstly up-regulated and thendown-regulated. In total of33protein spots were analyzed in radicle, of which14protein spots weredown-regulated,6protein spots were up-regulated,13protein spots were firstly up-regulated and thendown-regulated.2. There was temporal differentiation in radicle and hypocotyl responsing to aging stress.Compared with the control, most of differentially expressed proteins in radicle changed significantly inseeds with germination percentage of50%and5%, in which the proportion were34%and46%respectively. However, the changes were concentrated in hypocotyl of seeds with germinationpercentage of85%and50%, the proportion were55%and30%respectively.3. Differentially expressed proteins in radical and hypocotyl were successfully identified to match28and26diverse proteins respectively. Proteins in radical were divided into11function categories:26%proteins involved in protein translocation and storage,20%proteins involved in growth anddevelopment,14%proteins involved in protein biosynthesis,9%proteins involved in energymetabolism,9%proteins involved in signal transduction,9%proteins responsible for disease anddefense,6%proteins responsible for cell growth and division,3%proteins responsible for transport,3%responsible for secondary metabolite biosynthesis,3%responsible for amino acid metabolism and1%proteins were unknown. Proteins in hypocotyls were divided into9function categories:30%proteinsinvolved in protein translocation and storage,27%proteins involved in growth and development,9%proteins involved in protein biosynthesis,12%proteins responsible for disease and defense,3%proteinsresponsible for cell growth and division,9%proteins responsible for transport,3%responsible forsecondary metabolite biosynthesis,3%responsible for amino acid metabolism and4%proteins wereunknown.4. Some proteins were identified in both radical and hypocotyl, but the same protein may showdifferent expression patterns. These proteins were involved in storage proteins, LEA protein family, cellgrowth and division and secondary metabolite biosynthesis. Proteins related to other functions werecompletely different between radicle and hypocotyl. To conclude, there were some differences between radicle and hypocotyl, including number ofdifferentially expressed proteins, expression patterns and related metabolic processes. It was speculatedthat the differences may lead to differences of aging resistance between radicle and hypocotyl. Thechanges of mobilization activities involving storage materials, protein biosynthesis and growth anddevelopment may be closely related with the loss of soybean seed vigor.