Proteomic Study Of Leaf Senescence In Short-season Cotton Varieties

With the completion of whole genome sequencing in several species, proteomicapproaches were increasingly used in researching complex samples in large scale. Currently,proteomic studies based on various MS techniques have successfully identified large numberof proteins matching to50%-70%of the predicted gene models of various species.Two-dimensional electrophoresis (2-DE) is routinely used in proteomic research, and thistechnique has its own advantage in that it allows effective separation of hundreds of proteinsin one gel simultaneously and further acquisition of quantitative information of each proteinspots.Thus,2-DE technology has been widely applied for the profiling of plant development,the deciphering of biotic or abiotic stress such as water deficit, the characterization of plantmutants. To dissect the molecular mechanism underlying early leaf senescence in cotton andmine the potential target gene for related transgenic study, a comparative proteomic strategywas employed to investigate cotton leaf senescence using CCRI10as the experimentalmaterial, and differentially expressed protein spots were detected for further MS analysis.Bioinformatics study of these identified proteins could help us better understand thecomplicated process in cotton. Our results are as follows:1. Chlorophyll content assay was performed at30d、40d、50d cotton leaves sampledunder natural condition. Our results indicate chlorophyll content decreased sharply from30d-40d by50%, while chlorophyll content was only16%relative to the control at50d.2. Total protein were extracted from leaves at30d、40d、50d and were used forsubsequent2-DE analysis. The gel images were collected and Image Master2D was used forspot selection, calibration and quantization, and33protein spots were found to havesignificant changes.3. These protein spots were then excised from gels for MALDI-TOF-TOF analysis, and12protein spots were successfully identified.4. Bioinformatics study combined with quantitative information gained from ImageMaster2D analysis was conducted for these12protein spots, and the results show that6proteins involved in disease defense were significantly down regulated while only1proteinupregulated;2proteins involved in photosynthesis were up regulated while1protein downregulated;2proteins involved in signal transduction were down regulated.