A Preliminary Study Of The Mechanism Of Rna Editing In Rice In Response To H₂O₂ Stress

For most Chinese, rice is a very important food and is considered to be a strategic commodity in China. From a historical perspective, it plays a very important role in ensuring food safety. As a land area of one fourth of the world, water resources of China is only 2200m3 per capita and rice is the main water resource consumption, in more than 65% of the paddy field in China, drought is one of the important factors constrainting to rice production.The study of water-saving and drought-resistant rice(WDR) is particularly important, and anti ROS is one of the important part in drought resistance in rice.Huhan 1A and Huhan 1B,The water-saving and drought-resistant rice, were used as the research object,in the stress condition of H2O2. The physiological phenotype was investigated, and related physiological indexes were detected. With the RNA editing as the breakthrough point, to investigate the differences of RNA editing of mitochondrial genes in Huhan 1A and Huhan 1B under stress conditions, and to analyze the expression of mitochondrial genes. The main results and conclusions of this study are as follows:1、Under the 50 m M H2O2 stress treatment, the growth and development of the Huhan 1A and Huhan 1B were seriously affected, growth stagnation and yellow leaves appeared,chlorophyll concentration decreased.After 3 days in sresss condition, the chlorophyll concentration of Huhan 1A was significantly higher than that of Huhan 1b.Fixed fluorescence(F0) decreased significantly,Huhan 1A was significantly higher than that of Huhan 1B.The primary light energy conversion efficiency(Fv / FM) in Huhan 1A decreased significantly, but Huhan 1B did not change.2、After 3 days Stress treatment, H2O2、CAT、SOD、AOC、GPX、SP indexes in Huhan 1A and Huhan 1B appeared significant or extremely significant changes. The SP in Huhan 1A was significantly higher than that of Huhan 1B, and other indicators were Huhan 1B higher than Huhan 1A. APX and AOX did not change significantly after stress treatment, while the MDA content in Huhan 1A and Huhan 1B were the trend of first increased then decreased.3、RNA editing was found in the 8 genes of mitochondrial in Huhan 1A and Huhan 1B,87 editing sites were detected, all of which were found in the base substitution type of C-U, and the changes of amino acids to hydrophobic amino acids were detected. In Huhan 1A,nad7 has 1 site, ccm B has 10 sites, ccm C has 4 sites edited under H2O2 stress treatment, there are significant differences. nad2 has 3 sites, nad5 has 1 site, nad7 has 1 site, nad9 has 7 sites, ccm B has 20 sites, ccm C has 6 sites edited under H2O2 stress treatment, there are significant differences. In addition, The editing sites of ccm B-392308, ccm B-391917, ccm C-60565, ccm C-60508 in Huhan 1A just appear after the stress treatment,while the other 83 RNA editing sites already exist before stress treatment,only the editing frequency change.4、The gene expression of nad5 and Cox1 already exist differences in Huhan 1A and Huhan 1B.After stress treatment,the gene expression of ccm C、ccm B、nad2、nad7、atp9 exist significant differences.In Huhan 1A,the gene expression of ccm C、Cox1、nad5 were increased after stress treatment,ccm C and nad7 were decreased,nad2 was not changed.In Huhan 1B,the gene expression of ccm C and nad2 were decreased, ccm B、atp9、Cox1、nad5 were first increased then decreased,nad7 was increased.5、The content and enzyme activity of cytochrome c、NADH dehydrogenase、 ATP synthase were detected, after the stress treatment, in Huhan 1A, the content and enzyme activity of NADH dehydrogenase did not change significantly, the enzyme activity of ATP synthase was increased,the content was decreased,the content of cytochrome C were unchanged. In Huhan 1B, the content of NADH dehydrogenase and cytochrome C were unchanged, but the enzyme activity of ATP synthase was unchanged, the content decreased, and the enzyme activity of NADH dehydrogenase was increased first and then decreased. At the same time point, the enzyme activity and content were not significantly different in Huhan 1A and Huhan 1B.6、After stress treatment, the gene expression of Emp5-like, OGR1 and MPR25 had a significant change, and the change trend in Huhan 1A and Huhan 1B was consistent.Among them, the gene expression of Emp5-like and OGR1 were first increased and then decreased after stress treatment, while the MPR25 gene appeared a trend of decline after stress treatment. Before stress, the gene expression of Emp5-like was significantly higher in Huhan 1A than in Huhan 1B. After 3 days stress treatment, the gene expression of MPR25 was significantly higher in Huhan1 A than that of in Huhan 1B. In addition, the level of PPR gene expression may not directly affect the RNA editing frequency.In conclusion, this study has the following findings: 1 、Under exogenous H2O2 stress treatment, the phenotypes of Huhan 1A and Huhan 1B exist significant difference; 2、RNA editing involved in rice response to H2O2 stress; 3、A part of editing sites in Huhan 1A and Huhan 1b exist significant differences; 4、RNA editing may be plays an important role in rice response to adversity stress; 5、The editing type of RNA editing detected in this study are cto-u, meanwhile, RNA editing in amino acid propensity to form hydrophobic amino acids, speculated that RNA editing may alter protein structure, thus affecting the protein function.