The Response Of Water Stress On Physiological And Proteomic Levels In Cerasus Humilis Seedlings

Under drought stress, the plant cell regulates gene expression and protein changes by drought signal perception and transmission, causing the change in the levels of morphology, physiology, photosynthesis, respiration, and antioxidant system.Two years’Cerasus humilis (Huairou) seedlings was used in this study. We set three treatments, normal water supply (control), mild drought, moderate drought stress, and measured the parameters of photosynthetic, respiratory and antioxidant system. Especially, we analyzed and identified the different protein expression between the water stress and controls.Also.14genes involved in photosynthesis and respiration were selected to test the reliability of protein results by RT-PCR.The main results were as follows:1Under drought stress, peroxidase (POD) activity was increased in C. humilis seedlings, which might contribute to the adaption of plants exposed to water stress. However, the superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) activity were reduced to some extents. We found the changed of total respiratory, cytochrome and alternative respiration in C. humilis seedlings under water stress.. Rate of alternative respiration increased over time while cytochrome respiration g showed a trend of decline in C. humilis seedlings under water stress, which may be related to the lack of water in the plant cells. But The accumulation of soluble sugar content after water stress protect the plant against drought by osmotic regulation.2C. humilis protein with high stability was extracted and the system of two-dimensional (2-D) electrophoresis with high resolution, high repeatability was established.by optimizing pH range, load of strip, strip isoelectric focusing and electrophoresis time for SDS-PAGE.We compared the pH3-10and pH4-7range of strip, and found that the protein in the range of pH4-7is the most clear and reliable.3We identified76significant difference protein points (variation more than2times, P≤0.05) for C. humilis seedlings after water stress. Of76proteins,14proteins were up-expressed, while62were down-expressed, by the method of MALDI-TOFMS and Q TOFMS.4According to the protein function classification,48proteins were divided into11functional groups, which included photosynthesis, carbon and energy metabolism, protein hydrolysis, protein synthesis, protein folding and transport, transcription, intimidation and defense, membrane and transhipment, apoptosis, and other related proteins. On contrast to the already published known protein function, we also found that the two proteins of unknown function, which might provide new possibility to elucidate molecular mechanism in new ways.5We selected14protein from69, most of the which were involved in energy metabolism, sugar metabolism, stress defense related protein, to identified the reliability by RT-PCR. The results showed that these genes expression followed similar pattern with the changed of protein levels on the whole, indicating that proteins identification results were reliable.