| Drought is one of the major abiotic factors that strong influe nces plant growth,development and productivity. Wheat (Triticum aestivum L.) is one of the most importantfood crops in the world. Differential proteomics is an ideal means that has be en applied tofind new genes associated with drought resistance and drought responsive proteins. This willcontribute not only to the overall reveal of the genetic basis of drought response but also toclarifying the mechanism of drought resistance.Wheat seedlings with two leaves were treated with20%PEG. At the predetermined timepoint (0h、24h、48h and72h), the changes of root biomasses、seedling height、crownbiomasses、root/shoot ration、leaf plasma-membrane permeability、proline content and SODactivity were measured. The results showed that drought stress resulted in curly leaves andincreased number of fiberous roots. Under drought conditions, the increasement of rootbiomasses is very slowly and the seedling height was primarily suspended. The crownbiomasses showed a reduced trend. The ratio of root and crown was increased at first, then itwas decreased. The relative conductivity showed an increased trend, and with the stresscontinued, this value increased rapidly. The proline content was gradually increased at first,then it was increased sharply. The activity of SOD showed an increased trend at first, then adecreased one. However, all the values of SOD activity were higher than it from controlsamples at the same time point. It indicated, the drought stress simulated by20%PEGinhibited the growth inhibition and damaged the membrane. However, the survival of wheatplants suggested that they ha ve started a positive response mechanism to avoid death. Thephysiological response to drought stress proved the molecular mechanism in wheat plants.Using two-demensional electrophoresis (2-DE) method, we analyzed the proteinsprofiles of wheat seedlings which were drought treated for48h.27differentially expressedprotein spots with higher than2-fold spot thickness were found in gel image. These proteinspots were identified with MALDI-TOF/TOF and23spots were identified successfully.Compared to control, the abundance of19proteins increased and of4decreased. According tobioinformatics, these proteins were grouped into8categories, which mainly related to ROSscavenging and detoxifying enzymes、 photosynthesis and carbon fixation、 protein metabolism、 signal transduction、 amino acid metabolism、 cytoskeleton、 defense andmembrane lipid modification. The downregulated proteins are mainly related tophotosynthesis、carbo n fixa tion and cytoskeleton. The upregulated proteins are principallyinvolved in ROS scavenging and protein metabolism.LEA proteins are a group of proteins which are closely related with stress tolerance inplants.According to physicochemical properties of LEA proteins, we separated the heatstableand acid-soluble factions by boiling and3%TCA. And each fraction after each treatment wasverified by western blot analysis. We separated the heatstable acid soluble proteins by2-DE.After compared with the control samples,28differental protein spots were selected tosubjected MALDI-TOF/TOF analysis.12proteins represented by26spots were identifiedsusccesfully. Among them,9proteins are LEA proteins and three other proteins. LEA1groupincluded Em protein; LEA2group included Cor39、21-kDa dehydrin、16-kDa dehydrin andwheat cold induced16; LEA3group included ABA inducible protein and group3lateembryogenesis abunda nt protein; LEA5group included LEA D-34and late embryogenesisabundant protein. This research made our understanding to the sepration of LEA proteinsmore deeply.Using bioinformatics, we analyzed the sequences、seconde ry stucture、subcellularlocation and biological function of LEA proteins. The relevant pr edictive annotation indatabase provided very important theory foundation for futher research on these LEA proteins.All LEA proteins identified were mostly hydrophilic and natively unfolded, and theirsecondary structure contained a high propo rtion of rando m coil structure. Different LEAproteins localization features varied, while most of them were distributed in the nucleus,cytoplasm and mitochondria. The biological functions of the LEA proteins were different, andmainly focused on the protection of enzyme, binding with Ca2+, nucleic acid protection andcytoskeleton. Bioinformatics analysis of LEA proteins provides guidance for deeply study.Two cultivars of winter wheat (Triticum aestivum L.) differing in their drought tolerancewere subjected to a progressive soil water stress and recovery at four developmental stages.The relationship between the expression of dehydrins（LEA2） and developmental stages、genotypes and the level of water stress was studied. Some results were obtained. No dehydrinexpressed in the leaves from the well-watered plants. With water loss, the amount of thedehydrins gradually increased and the amount decreased after rehydration. The expression ofdehydrins is dependent on the developmental stage. Not all the same dehydrins wereexpressed at different de velop mental stages. The expression of dehydrins is depe nde nt on thegenotype. Although there were same de hydrin expressed in different genop tyes, there wereanother de hydrins expressed in a ceratin wheat genotype. Combined with LEA proteomics in our resuarch, Cor39(45-kDa), which were sperated with boiling and TCA treatment, mayplay a fundamental and impor tant role in two wheat genotypes and four develop mental stages.This research laid the foundation for the specific function of45-kDa dehydrin. |
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