| Low temperature is one of the most serious environmental stresses affecting the grain yields and quality of rice. Accompanied by frequent extreme weather events such as cold snaps, research on mechanism of cold tolerance in rice and breeding for cold resistant varieties is imminent. Based on two dimensional electrophoresis (2-DE) and bioinformatics analysis of mass spectrometry data, we preliminary surveyed the cold tolerance of cold sensitive variety9311and cold resistance variety Fujisaka5under cold stress.The main results of the study were as follows:(1) Established2-DE map of9311and Fujisaka5. From the93112-DE map,36proteins were found presenting more than twofold difference with2up-expressed and34down-expressed, and28proteins were successfully identified as27ones. From the Fujisaka2-DE map,43proteins were showed more than twofold difference with24un-expressed and19down-expressed, and35proteins were successfully identified as32ones.(2) Through bioinformatic analysis, it was found that the differentially expressed proteins mainly contained chaperones, antioxidant enzymes, ascorbic acid enzyme, glutathiones peptidyltransferase enzyme Ⅱ, heat shock protein GrpE protein, protein kinases, enzymes of the photosynthetic system, mature enzyme K, ATP-dependent zinc metalloprotease FTSH2etc. Function of these proteins involved in many aspects. As for the biological process, the largest kind of proteins responding to cold stress was metabolic, the second and third kind were cell process and response to stress, with the averages of70%,65%,40%. As for molecular function, it mainly involved in binding, catalysis, and transport, with the proportions of approximately50%,55%,10%. As for cell component, it were mainly the content of cell, organelles and capsular, with the percents of about78%,75%,30%. In addition,4unknown function proteins from9311and3unknown function proteins from Fujisaka5were also found. Further analysis showed that the ways taken part in by differently expressed protein mainly contained metabolism, biotic and abiotic stress, protein metabolism and modification, carbohydrate metabolism, metabolism of the base compound, precursor metabolism and energy production, photosynthesis and transportation. These results suggested that it should be a very complex process for rice to resist to low-temperature damage.(3) By comparing the two varies of rice, it can be found that cold stress-related protein from9311most down-regulated and that from Fujisaka5most up-regulated. The proteins involved in the pathway of metabolism accounted for the largest proportion of both9311and Fujisaka5,which is more than60%. The percent of stress-responsive protein of9311was much higher than that of Fujisaka5, they were up-regulated except ATP synthase. The proportions of differently expressed protein involved in the pathway of energy and photosynthetic from9311was lower than that of Fujisaka5, and most of them down-regulated.The above results show that under the cold stimulation, as the membrane composition and structure were damaged, metabolism has been changed dramatically and rice defense system was activated.For Fujisaka5,the activities of proteins related to biotic and abiotic stress,energy metabolism and photosynthesis were enhanced in order to protect plants under cold stress. There are59proteins related to the resistance of cold stress were identified in our study, and we have investigated and classified all of their biological functions. The importance of our study are providing some conduct for the research of rice resistant to cold stress, supporting auxiliary technique for rice varieties and widening the search field of cold tolerance in plants. |
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