Proteomic Analysis Of Wheat Leaves Under Low Temperature Stress

The low temperature is one of the major abiotic stress factors in the growth and development of plants.It severely restricts the crop production,stable production such as spikes,grain number,grain weight.Recently years,with the frequency increaseing of spring freeze stress in Huang Huai area,the Wheat suffered from more and more serious damage under low temperature stress.Therefore,it is of great significance to study the mechanism of damage and to cultivate new varieties with strong resistance to reduce the injuried under low temperature.In this study,Zheng Hua 0840-3(LT sensitive)and Ai kang 58(LT insensitive)were studied as experiment materials.Using the method of hydroponics,the changes of(MDA)content,relative electrical conductivity,soluble sugar content,superoxide dismutase(SOD)activity were studied under low temperature stress for 72 h at-5 ? in different wheat varieties leaves.Meanwhile,the changes of proteomes with Zheng Hua 0840-3(low temperature sensitive materials)and Ai kang 58(low temperature insensitive materials)at room temperature and under low temperature for 72 h at-5 ? were analyzed by two-dimensional gel electrophoresis and mass spectrometry electrophoresis.The main results were showed as follows:1.With the extension of stress time,they both appeared wilting phenomenon in different degrees,while Zheng Hua 0840-3 seemed more serious than Ai kang 58,we can directly see cold hardiness of the two varieties of wheat.The content of MDA was increased in Zheng Hua 0840-3(LT sensitive)and Ai kang 58(LT insensitive),while the changes trend of MDA content is higher in Zheng Hua 0840-3(LT sensitive).It showed that low tempature induced antioxidant protein expression to improve the tolerance of wheat under low temperature environment.The soluble sugar content and SOD activity trend was also increased in both varieties,howerer,Ai kang 58((LT insensitive)increased more than Zheng Hua 0840-3(LT sensitive),It showed that low temperature stimulated metabolism in plants to adapt to the pressure of environment's change.The relative conductivity was both increased in Zheng Hua 0840-3(LT sensitive)and Ai kang 58(LT insensitive),while the changes trend of relative conductivity is higher in Zheng Hua 0840-3(LT sensitive).It indicated the extent of low temperature damage on LT sensitive wheat leaf cells was more seriousthan LT insensitive,the leakage of intracellular electrolyte was more in Zheng Hua 0840-3,it also reflected the differences in cold hardiness.2.Two varieties Zheng Hua 0840-3(LT sensitive)and Ai kang 58(LT insensitive)were used to analyze the total protein profile under low temperature at 72 h at-5 by? two-dimensional electrophoresis and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry method.While using the spike of under normal growth temperature condition as control the results show that there are 1100 to 1200 protein spots for each variety within the range of to p H 4 to 7.After 72 h of low temperature,we selected 87 proteins spots which were significantly expressed and the expression ratio>1 under 2 temperatures stress condition.There were 59 protein spots identified by mass spectrometry analysis.17 up-regulated and 27 down-regulated protein spots were found in Zheng Hua 0840-3,4 new protein spots appeared and 3 protein spots decreased.while 4 up-regulated and 24 down-regulated protein spots in Ai kang 58,5 new protein spots appeared and 8 protein spots decreased.Using protein Blast methods,the identified cold stress responsive proteins were classified into 9 groups including protein metabolic process,energy metabolism,TCA pathway,glycolysis,carbohydrate and energy metabolism,nucleic acid metabolism,photosynthesis,stress/defenseand other unknown function.Some of the expressed proteins were enhanced significantly in LT insensitive varieties while they were not expressed in LT sensitive.These proteins maybe related to metabolic regulation or response characteristics of wheat spike under low temperature stress.Quantitative PCR was used to analyze the expression of 17 genes involved in the response to low temperature stress.The results showed that m RNA was not consistent with the protein level.In this study,the mechanism of low temperature stress response of wheat was explained from the protein level.