| Preteomics study is playing an increasingly important role in the functional genomics era. Two-dimensional electrophoresis is one of the key techniques in proteomics studies. Salt stress is one of the key abiotic stresses effecting crop yields in the world. About20%land or50%irrigated land of the world were affected by salinity. Soybean was not only the key food crops, but also the important feed crops in the world. And soybean was also one of the salt-sensitive crops. Therefore, it is an important task to dissect the mechanisms of salt adaptive soybean with the aim to cultivate new salt tolerant varieties.Firstly, in our group, we verified the salt tolerance of Jackson (salt-sensitive) and Lee68(salt-tolerant) which were identified by predecessors. A proteomic study was conducted to determine the difference in young root and leaf proteomes of Jackson (salt-sensitive) and Lee68(salt-tolerant). Differences in proteomics response of the Jackson and Lee68under salt stress (CKã€1hã€2hã€3dã€6d) were analysed and differentially expressed proteins were analysis by MALDI-TOF-TOF MS. RT-PCR assay was used to analyse the transcription patterns of31selected differentially expressed proteins to investigated the correlation between transcription and translation. Taken together, responsive characteristics of Jackson and Lee68under salt stress were systematically investigated at translational levels, and the mechanisms of salt sensitive and salt resistance are discussed.1. Salt stress have an inhibition effect for soybean seedling growth. But the decrease of Lee68(high salt tolerant) seedling height was less than that ot Jackson (salt sensitive). This verified that the salt tolerant of Lee68was stronger than that of Jackson.2. In total,124differentially expressed proteins were obtained in roots of Jackson and Lee68seedlings under salt stress. Of the94were identified by MALDI-TOF-TOF MS. First, root proteome of Lee68was markedly different from that of Jackson. Results showed that one spot was special to Jackson and five spots were particular to Lee68. Second, difference was there in expression patterns of salt-induced proteins between Jackson and Lee68. Among the4salt-induced proteins, two were specific to Lee68and two were induced in both of them. Third, there were distinguishing differences in root expression patterns under salt stress. Analysis from genotype differences, percentage of expression changed (up-regulated and down regulated) in Lee68root was taller than that of in Jackson root both under short and long salt stress. It indicated that salt stress may induce more dramatically course of response in Lee68root than that of in Jackson. Fourth, difference was there in expression patterns of unexpressive proteins between Jackson and Lee68. Among the3salt-inhibitted proteins, one was inhibitted in Lee68and two were inhibitted in both of them.3.118differentially expressed proteins were found in leaves of Jackson and Lee68seedlings under salt stress,103were identified by MALDI-TOF-TOF MS. Comparative analysis showed that the state was similar to roots. First, leave proteome of Lee68was markedly different from that of Jackson. Results showed that three spots was special to Jackson and three spots were particular to Lee68. Second, difference was there in expression patterns of leaf salt-induced proteins between Jackson and Lee68. Among the8leaf salt-induced proteins, one was specific to Lee68, one was specific to Jackson and six were induced in both of them. Third, there were distinguishing differences in leaf expression patterns under salt stress. Percentage of expression changed (up-regulated and down regulated) in Lee68leaf was lower14.1%than that of in Jackson root under short salt stress. But percentage of expression changed (up-regulated and down regulated) in Lee68leaf was taller8.2%than that of in Jackson leaf under long salt stress. This indicated that the changed in Lee68leaf was slower than that in Lee68root. Root proteins were more sensitive than leaf proteins. Fourth, difference was there in expression patterns of unexpressive proteins between Jackson and Lee68. Among the4salt-inhibitted proteins, one was inhibitted in Lee68, one was inhibitted in Jackson and two were inhibitted in both of them.4. Significant difference between root and leaf proteomes under salt stress. A remarkable difference was the energy metabolism associated proteins which was the biggest group (39) in leaf but only six in root. The stress defense and transcription and translation related proteins were not found in root, but that were found2and4in leaf, respectively. The cell cycle, nucleotide metabolism and transporting related proteins were not found in leaf, but that were found2,1and4in root, respectively. Some pathways (detoxifying, signal transduction, carbohydrate metabolism, amino acid and nitrogen metabolism, proteolytic, secondary metabolite biosynthesis and anti-nutritional factors) involved more changed proteins in root than in leaf. And some pathways (energy metabolism, protein synthesis, protein folding and assembly and cytoskeleton and cell wall synthesis) involved more changed proteins in leaf than in root. Thereby, proteomes of root was more sensitive to salt than proteomes of leaf. Roots can reflect salt tolerant of plant and involved pathway more accurately than leaves under salt stress5. In our results, transcription and translation had a good relativity. Thereby, to understand the response traits to salt and mechanism of salt tolerant from protein levels, it was necessary that some key proteins was carry out RT-PCR.6. Significant difference between Jackson and Lee68proteomes under salt stress. The detoxifying and energy system were better than Jackson. And ethylene emission of Lee68was more than Jackson. These may be Lee68’s key reasons for its salt tolerance. Furthermore, some putative pathways of salt tolerant mechanism in soybean were found. They were cell cycle, stress defense, protein folding and assembly, amino acid and nitrogen metabolism, cytoskeleton and cell wall synthesis and flavonoid and phenylpropanoid biosynthesis. Some putative pathways of salt sensitive mechanism in soybean were transporting, isoflavonoid biosynthesis, photosynthesis, glycolysis, TCA cycle, protein biosynthesis, stress defense, detoxifying and proteolytic.Secondly, to better understand the salt tolerance mechanisms in jute, morphological, physiological and proteomic analyses were performed on two jute genotypes (salt-sensitive genotype Mengyuan and salt-tolerant genotype9511) exposed to nutrient solutions including0,50,100, and150mM NaCl, respectively, for four days. Our results indicated that genotype9511, with lower degree of average index of salt harm (AISH) in leaf, less fallen leaf number/ten plants and higher root proline (Pro) content, was more salt tolerant than Mengyuan. Two-dimensional gel electrophoresis (2-DE) and image analyses showed that expression pattern of44protein spots significantly (P<0.05) changed in roots of both genotypes in response to the stress. MS/MS was further used to identify the differentially expressed protein spots. The identified root proteins were grouped into three groups including13regulatory proteins, involved in signal transduction, and transcription and translation, and26functional proteins, involved in redox homeostasis, transposon regulation, photosynthesis, metabolisms of energy, lipid, nucleotide, and glycan biosynthesis and metabolism, cell wall metabolism and cytoskeleton rearrangement, and five function-unknown proteins. Our results suggested that the pathways regulated by the identified functional and regulatory proteins may establish a new homeostasis after stress, which is an important survival mechanism of jute upon NaCl stress. |
