| Gossypium hirsutumis an important salt tolerance crop which is one of the most important economic crops in the world.While soil salinity isan important limiting factorto the development of agricultural productionand the improvement ofecological environment. Salt resistantof plants involved in many physiological and biochemical factors, which is controlled by multiple genes. The presentation states and adaptation mechanisms of plants with different varieties under salt stressmay exist differences. Cotton genotype CCRI 69 was selected as the material to analyze the changes in physiological and proteome under salt stress in this study. The aims are to explore the molecular mechanism of cotton seedlingsresponse to salt stress and to lay the foundation for further research on the related gene function of cottonunder salt stress. The main results are as follows:1. The morphological index of cotton seedlings under different salt stresslevels were studied. The cotton hypocotyls beceme yellow in the germination period under salt stress;the seedling leaves were wilted in the growth period;the edge of leaves appeared yellow;the cotyledon stretched irregularly; the primary roots became slender and the seedling roots became brown from milky white.2.Physiological and biochemical analysis of cotton under salt stress. The resultsshowed that: with the increase of salt concentration, chlorophyll content, superoxide dismutase(SOD) activity and root activity decreased gradually in leaves ofcottonseedlings while the accumulation of proline was increased with the increase of salt concentration; the peroxidase(POD) activitywas not significantly different. The chlorophyll content between untreated and Na Cl-treated seedlings was very close in low salt concentration, but decreased sharplywhen the salt concentration was increased to 1%; when salt concentration was over 1%, SOD activity no longer; the root activity less decreasedwhen salt concentrations less than 0.5%, however, it obviously declined when the salt concentrations was over 1%.3.Optimization of the extraction method of cotton protein. The separation method of thetwo-dimensional gel electrophoresis(2D-PAGE) based O’Farrell’s method was established. The extraction of leaf proteins was used the combinationof liquid nitrogen grind with TCA-acetone method, and the extraction of root proteins was used the method of the combination of phosphate buffergrindwith TCA-acetone method;7 M urea lysis buffer was used to lysis proteins, and the suitable loading quantity was 300μg for 2D-PAGE separation.4. The root proteins from cottonseedling under salt stress were extreated and seperated by 2D-PAGE.The protein expression maps which had high protein abundance, clear background, high resolution was obtained. The gels were resolved by PDQuest8.0.1 software and the results showed that: 185 protein spots were successfully matched, andthe expression levels of 36 proteins were fluctuated response to salt stress. Of them, 16 proteins were significantly up-regulated, 20 proteins were significantly down-regulated.5. Ten differential protein spots were chosen to identify by MALDI-TOF-MS/MS. The homologous identification of the cotton root proteins indicated that these proteins were ascorbate peroxidase(APX), enolase, glutathione-S-transferase, quinone oxidoreductase, annexin Anx Gb3, chloroplast Rubiso enzyme subunit binding protein alpha subunit, P23, fructokinase, alcohol dehydrogenase, adenine phosphoribosyl transferase-1-subtype-1.6. The possible mechanisms of resistance to stress were analyzed. Thepreparation of samples to 2D-PAGE was also discussed, which provide certain basis for the further researches. |
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