Study On Genetic Characteristics And Physiological Characteristics Of Transgenic Hybrids Of OsSRT Gene In Rice

Structure unit of nucleosome chromosome is consisted of DNA and histones in eukaryotes. Histone of chromatin plays an important role as alkaline protein in the cell nucleus. Protein modification has become a hot research spot in recent years, which including methylation, glycosylation and acetylation. There are few researches about the acetylation of histones at present. Histone acetylation is completed by histone acetyltransferase, and histone deacetylation is completed by histone deacetylase, both of them play an important role in chromosomes structure modification and gene expression regulation by influencing the transcription process in the cell, and keep dynamic balance. Histone acetylation enzyme exists in all eukaryotes, it can make the cell transcription can’t proceed, thus plays an important role in chromosome structure modification and gene expression regulation. But what kind of effect on the growth and development of plants is not very clear, which is the focus of this experimental study.Histone deacetylase could be divided into three subfamilies: RPD3/HDA1, HD2 and SIR2. In this study, gene OsSRT1（ID: Ak069000.1） is homologous gene with gene SIR2 in rice. Engineering strain with target gene OsSRT1 is used to infect Arabidopsis thaliana and rice by agrobacterium-mediated method to cultivate OsSRT1 over-expression Arabidopsis thaliana and rice plants. Callus of rice is infected and transformed by Agrobacterium-mediated transformation, then infected callus is screened to be regeneration of differentiation and differentiate into seedlings eventually. Total RNA Of transgenic rice is extracted, and transgenic rice is obtained by Rt-pcr screening finally. This test compares the physiological and biochemical data of T₂, OsSRT1-16 over-expression Arabidopsis thaliana and RNAi-Ossrt1 Arabidopsis thaliana（Ossrt1-1, Ossrt-2） to reveal the gene functions in rice to study the function of gene OsSRT1 and its relationship with the stress. To understand the purpose of the role of genes in plant stress mechanism, and it has important scientific significance in improving the ability of plants under the stress.Genetic performance results were as follows: there was great differences between the growth situation of over-expression T₂-OsSRT1-16 and T₂-Ossrt1 Arabidopsis thaliana. At normal cultivation conditions, T₂-OsSRT1-16 Arabidopsis thaliana had the best growth situation compared with the other three groups, its leaf was larger and root system was relatively flourishing, while T₂-Ossrt1 Arabidopsis thaliana had the worst growth situation: the stem and leaf was smaller, the color was yellow-green and the root was short. Obvious differences were observed with the stress treatment of 100mmol/L NaCl: fresh weight and root length of T₂-OsSRT1-16 were apparently better than that of T₂-Ossrt1 and control group Arabidopsis thaliana; differences were obvious when the concentration of NaHCO3 was 10 mmol/L: fresh weight and root length of T₂-OsSRT1-16 were better than that of control group Arabidopsis thaliana, and fresh weight and root length of T₂-Ossrt1 were worse than that of control group Arabidopsis thaliana.Arabidopsis T₂-OsSRT1-16 and T₂-Ossrt1 was under stress conditions of different concentration of NaCl and NaHCO3. Praline content, soluble protein content, conductivity, chlorophyll and hydrogen peroxide enzyme activity of Arabidopsis thaliana were determined under different concentration. The result showed that the physiological and biochemical indexes of transgenic and over-expression Arabidopsis thaliana were better than the control group and RNAi Arabidopsis thaliana.Through the study of rice mature embryo callus regeneration method, rice callus were induced and differentiation and growth of plantlets were filtrated, and had genetically modified rice. Extracted the rice total RNA and used RT-RCR method to test genetically modified molecules, the results showed that OsSRT1 genes can integrated into the rice successfully, and can be normal transcription. With the saline-alkali stress to the better transgenic rice of T0-OsSRT1-2 and control group, the results showed that under the stress of NaCl and NaHCO3, the proline content and hydrogen peroxide enzyme activity had an obvious rise after cultivating for 3 days to 7 days, and the increase rate of proline with T0-OsSRT1-2 was higher than control group. The speed of hoist with T0-OsSRT1-2 rice was higher than control group.Through this research, by contrasted gene OsSRT1 transgenic Arabidopsis and rice with control group and RNAi plant in genetic and physiological performance, gene OsSRT1 function and relationship between OsSRT1 transgenic offspring and the stress were more clearly. It has important scientific significance to understand the purpose of the role of genes in plant stress mechanism and improve the ability of plants under stress.