Proteomic Analysis Of Cottonleaf During Drought Stress

With remarkable changes of the global climate, more and more frequent and serious drought stresshas become one of the most leading elements limiting the global agricultural production. Cotton, one ofthe most important economic crops in China, is limited planting almost in arid or semi-arid regionalareas for its drought stress sustainable ability. Drought stress influences significantly cotton productionin our country. Protein is the ultimate performer in life activities, and proteomics research is becomingmore concerned by scientists all over the world. Now the proteomics methods have been used toidentify plant drought stress protein on some main crops for further research on drought-resistantmechanism in plants. But on cotton, the proteomics research of drought stress hasn’t yet been reportedand the mechanism influencing drought stress was still unclear by now. In this paper, to study thevariations among protein paterns under drought stress,16accessions were chosen at first from fourcotton speices of Gossypium germplasm, and then two of which were finally chosen for proteomicsindentification.First，the study of variations of protein components was conducted under drought stress. We choose16cotton accessions with drought-tolerant and drought-sensitive accessions from the four cultivatedspecies. On the tri-leaf stage of seedlings, the protein extracted method of cotton leaves was optimized,to determine four kinds of protein under the stress of the control, mild drought and heavy drought. Theresults indicated that there was remarkably different of protein levels in different materials, Glutenin isthe most, Albumin, Globin and Prolamin are relatively lower. The content of protein component inleaves was greatly different in different cotton cultivars, the protein content in G.hirsutum andG.barbadense was relatively hight, among which the content of Albumin and Globin is higher thanDiploid cotton, but Globin and Prolamin in Diploid cotton was relatively high, the variation of proteincontents in different cultivars. The studies also showed that different drought resistance level changedgreatly after drought stress, which showed the diversity of protein metabolism.Second, drought-resistant upland cotton （Gossypium hirsutum L.） variety, Zhong H177anddrought-sensitive variety, Zhong s9612, were choen and used as materials by setting the different watersupply （and the control） at seeding stage by setting the normal water supply and water controlcomparison test at tri-leaf stage of seedlings, stress-induced proteome changes were conducted bytwo-dimensional gel electrophoresis. The result indicated that there were total30differentiallyexpressed proteins discovered in Zhong H177under stress, among which15up-regulated,10down-regulated,1newly-appeared, and3disappeared protein spots reproducibly presented differentialexpression patterns on2-DE maps.49differential proteins were discovered under stress, among which31up-regulated,13down-regulated,4newly-appeared, and1disappeared protein spots reproduciblypresented differential expression patterns on2-DE maps.43differential proteins were identified andconfirmed by MALDI-TOF-TOF MS, Functional classification analysis indicated that drought stressproteins were related in photosynthesis, metabolism, tress tolerance, and solute translocation. The stability of photosynthesis, the efficiently of metabolism system, the excellent of antioxidase system andthe strong of ion transport system, had been found preliminary important roles in maintaining thegrowth of cotton under drought conditions.Through the above analysis, protein changed in cotton leaves under drought stress was discovered,mainly by albumin, globulin and gliadin content changes, and the differences in drought-resistant waseasier to observe than the drought-sensitive materials. Mass spectrometry had identified a group ofproteins, closely relating to drought stress, including Rubisco enzyme and ATP synthetase, whcich wasvery different in drought tolerance between drought-resistant materials. The results could be used as apreliminary screening for drought resistance germplasm. These studies could give us a deeperunderstanding of cotton in response to drought stress mechanism, providing the basis for the genecloning related to drought stress, which could lay sound foundation for the future breeding indrought-resistant cotton.