The Reasearch On Proteome Of Leaves And Roots Frome Triticum Boeoticum L. In Response To Drought Stress

As a main abiotic stresses, drought stress seriously limit crop growth, development and production in majority of agriculture fields of the world. Wheat(Triticum aestivum L.) is one of the worldwidely cultivated and staple crops, which belongs to gramineous plants, its yield and quanlity are easily affected by climatic temperature change and water resources scarcity in the environment, the loss in wheat production caused by drought is equal to the sum of other non-biological adverse stress. As above, it is top priority task to systematically investigate the mechanism of wheat response to drought stress and cultivate the drought resistance of wheat varieties.The genome of the common wheat is AABBDD, such large and complecated genome significantly restrain the isolation and identification of genes related to drought response. Triticum urartu and Triticum boeoticum are both diploid wheat species(the genome is AA), the genome composition is much simpler compared to common wheat species. Triticum urartu is one of the ancestors of common wheats, and the genomic sequencing project for Triticum urartu were finished. Comparing with the Triticum urartu and common wheats, Triticum boeoticum is more drought-resistant, therefore it is an important gene pool for improving the drought resistance of common wheats. Hence, the investigation of the drought response mechanism underby Triticum boeoticum would greatly contribute to uncover the molecular base of drought response in common wheat. Proteins are the major executor of cellular function, the investigation of the proteome change in Triticum boeoticum under drought stress would greatly contributed to the investigation of the molecular mechanism for drought response.At present study, Triticum boeoticum are cultured and treated with drought stress in greenhouse conditions, which is induced by 20% PEG-6000 in Hoagland solution at the three leaves stage, while the control groups were cultured in Hoagland solution in the same growth conditions. The leaves and roots were collected at 24 and 48 h of drought treatment, the analysis of physiological, biochemical and proteomics changes in the leaves and roots were conducted. The MALDI-TOF-TOF analysis were applied to identify the differential expressed proteins(DEPs), the molcular function, biological and metabolic process of the DEPs involved in drought were also analyzed as well. The main purpose of this study is to analyze physiological and proteomic change in leaves and roots of Triticum boeoticum under drought stress, and to provide some valuable information for the uncovering of drought response mechanism in Triticum boeoticum. And the main results are shown as follows: 1. The content of ABA, soluble sugar and proline were increased under drought stress, as well as MDA content. Suggesting the signal transduction and capability of osmotic adjustment were enhanced, but the cell membrane was also damaged by lipid peroxidation. The content of chlorophyll a and b were decreased, the photosythsis rate, transpiration rate, intercellular CO2 content were also reduced, indicating the inhibition of photosynthetic process. 2. Comparative proteomics results indicated that 115 and 102 protein spots in leaves and roots respectively, exhibited at least 1.5-fold differences(p≤0.01). Of the differential expressed proteins(DEPs), 17 and 16 spots from leaves and roots respectively were induced under drought stress, while 3 leaves spots and 4 roots spots were totally suppressed. These proteins may act as the key proteins in responnse to drought stress, and be worth of subsequent in-depth study. 3. All the DEPs above were analyzed by MALDI-TOF-TOF. Totally, ninety-eight in the wild wheat leaves and 85 in roots were successfully identified. Of the 98 identities in leaves and 85 in roots, 85 and 80 unique proteins have been documented in the current database as putative functional proteins, respectively. After comparism of proteome between leaves and roots, only 6 unique proteins were common in leaves and roots, indicating the existence of different responsing mechanism between leaves and roots. 4. Molecular function classification results showed that all the successfully identified DEPs by MALDI-TOF-TOF could be classified into 14 and 12 function groups in leaves androots respectively, such as photosynthesis, carbon metabolism, detoxification and defense. We also analyzed the sub-cellular localization of these DEPs, and the results showed that most of the DEPs in leaves were localized in chloroplast(33.67%), cytoplasm(29.59%), mitochondria(19.39%) and nucleus(14.29%). For root proteins, most of the DEPs were localized in cytoplasm(36.47%) and mitochondria(49.41%). 5. To confirm reliability of the DEPs identified in 2-DE analysis, ten DEPs(Five from leaves and five from roots), were selected randomly to conducted Western bloting analysis with protein samples of the three time point(0, 24 and 48 h). The result indicated that the protein level of these DEPs were consistent with the 2-DE results. The Western bloting results seemed to agree well with the proteomic results. 6. Molecular function and Metabolic pathways analysis results showed that the signal transduction-involved proteins were greatly up-regulated in roots, indicating enhanced stress-responsive signaling pathways in the roots of the wild wheat seedlings exposure to short-term drought treatment; the ROS scavenge capability and pathogenesis defensive network were enhaced both in leaves and roots as well. The glycolytic pathway were inhibited, while the pentose phosphate pathway was enhanced in roots under drought stress. Photosynthesis and carbon fixation pathways were suppressed in the leaves of wild wheat plants exposure to short-term drought, while tricarboxylic acid cycle(TCA) pathway were enhanced. Consequently resulted in the complicated change of energy metabolism, and a new homeostasis was established. The amino acid and protein metabolism were suppressed in roots, while enhanced in leaves. Totally, there are some common character in leaves and roots in response to drought stress, as well as the existence of tissue specific mechanism.