Peg6000, Simulated Drought Stress On Rice Proteome, And Differences In Protein Function Analysis

In the experiment, the responses of rice (Oryza sativa L., cv. Zhong Han3, ShanYou 63 and AiZaizhan) to drought stress (simulated by 10%PEG6000) were investigated by proteomic analysis,physiological and biochemical determination, and protein methylation assay. Conclutions presented in the thesis can be summarized as follow:1. The physiological and biochemical effects of PEG6000 stress in rice seedlingsPEG6000 could lead to water deficit in rice seedlings ,decreased the relative water content. PEG6000 increased significantly the MDA content in rice leaves and roots, which indicated that PEG6000 caused lipid-peroxidation, hence, the structure and physiological functions of membrance were damaged. PEG6000 influenced the protein content in rice seedlings. Protein content in leaves have a slight increase during the initial stage (1 days) in the drought treatment period, and protein content decreased rapidly with treatment time extension. Whereas, the protein content in the roots showed a slight increase after the first drop and then a downward trend with treatment time extension.Comparing the physiological damage among the tested three rice varieties, the conclusion can be drawn that the sensitivity of the tested rice varieties to drought stress was AaiZaizhan>ShanYou63>ZhongHan3.2. Effects of PEG6000 on proteome in rice leavesPEG6000 stress had significant effect on global proteome in rice leaves. PEG6000 stress inhibited the protein expression in AiZaizhan leaves. Both inhibitory and inhibiting effect on the protein expression in ShanYou63 leaves, and only inhibiting effect on the protein expression in ZhongHan3 leaves treated by PEG6000 was observed. It may be one of the important mechanisms for the tested varieties have different sensitivity to drought stress.The analysis of the category and function of stress inducible and inhibitory proteins showed that different proteins in Shanyou 63 leaves were inhibitived in response to PEG6000 stress. They are chloroplast Ferritin 1 , ribulose- 1,5-bisphosphate carboxylase activase,microtubule binding protein,sucrose synthase,ribulose bisphosphate carboxylase large chain,chloroplast inner envelope protein,plastid-specific ribosomal protein. Furthermore, most inhibitory proteins were localized in chloroplast, which indicated that photosynthesis system was the most sensitive in Shanyou 63 leaves to drought stress.Meanwhile, different group of proteins in ShanYou63 leaves were induced in response to PEG6000 stress. They were the substance and energy metabolism-related enzymes (such as , glyceraldehyde-3-phosphate dehydro- genase, ATP synthase alpha chain, H+-transporting two-sector ATPase, UDP-glucose pyrophosphorylase), protein translation regulative protein (such as, mRNA-binding protein), activity methyl cycle and transfer related enzyme (such as , 5-methyltetrahydropteroyltriglutam ate-homocysteine methyltransferase), and antioxidant-related enzyme (such as, monodehydroascorbate reductase). In addition, the ribulose bisphosphate carboxylase large chain and monodehydroascorbate reductase in ZhongHan3 leaves were also induced in response to PEG6000 stress.3. Effects of PEG6000 stress on protein and DNA methylation .PEG6000 stress elevated protein and DNA methylation rates, and also promoted methylation of Rubsico large and small subunit in the rice leaves.