Comparative Peoteome Analysis Of Early Senescence In Gossypium Hirsutum Leaves

Cotton is one of the most importance ecnomomic crops and it is strategic goods which have a close relationship with our country's economy and people's life. However, our country has so much people while only has limited land, the contradictory between cotton and grains is very severe. An effective method to solve this problem is to promot the short-seasoned cotton. But short-seasoned cotton always has the problem of early-senescence which has negative influence on the cotton yield,fiber length,fiber strength and quality of cotton. Therefore, to improve cotton production and cotton fiber quality, the study of cotton premature aging mechanism is significant.A great number of genes specifically expressed in cotton leaves have been isolated during leaves senescence, and mechanisms of leaves senescence have eluted in functional genomics, but proteins participated in this process are still unknown. In recently years , Comparative proteomic has become an powerful tool to identify protein changes during various developmental processes including leaf senescence, fruit ripening, and early flower development. In this study, we took a proteomic approach that two-dimensional electrophoresis combined with mass spectrometry proteomics method, to identify proteins that potentially involved in cotton leaves during senescence. Total protein was extracted and separated by TCA-acetone. High quality 2D gel maps are essential for detailed quantitative analysis and protein identification. Protein spots from all the replicate gels were compared and quantified using the ImageMaster 2D Platinum Software Version 7.0. The normalized percentage volumes (% Vol) of protein spots from triplicate biological samples were subjected to statistical analysis using means standard errors. The protein spots which exhibited reproducible and significant changes (>1.5 fold and p-value < 0.05) were included for further analysis. After a spot-to-spot comparison and statistical analysis, a total of 92 stained spots were found to have significant changes. Of these, 52 spots were up-regulated, and 40 spots were down-regulated in senescence leaves. All identified proteins were annotated and were classified into functional classes according to the COG pathway database: carbohydrate transport and metabolism in the total identification of protein 47.44%; posttranslational modifications, protein turnover and molecular chaperone 19.23%, energy production and conversion 12.82 %, inorganic ion transport and metabolism 10.26% and amino acid transport and metabolism 2.56%, there are some proteins involved in other metabolic processes and functions of unknown proteins. Gene expression was determined by real time -polymerase chain reaction, althought the results of RT-PCR is just partly consistent whih the performance of the protein. These results suggest that proteomics is an effective method to study of different proteins during leaf senescence, and comparative proteomic analysis provides new insights into the regulation of leaf senescence in cototn.