An Initial Study Of Methionine Sulfoxide Reductase Function In Stress Resistance In Oryza Sativa L.

Methionine (Met) is a important sulfur-containing amino acid residues in polypeptides and proteins. Met is susceptible to ozone, peroxide of hydrogen and hydroxyl radicals and other reactive oxygen oxidation of methionine-R, S-sulfoxide (Met-R, S-SO), which can lead to reduced or loss of the biological activity of the protein. Methionine sulfoxide reductase (MSR) can be in vivo of methionine-R, S-sulfoxide reduction of methionine, for which it resume protein activity. Three types of MSR, MSRA, MSRB and fRMSR, are identified for the moment. MSRA and MSRB selectively reduce the two MetSO epimers, either the free or the peptidyl methionine-S-sulfoxide and methionine-R-sulfoxide respectively, while fRMSR only reduce free methionine-R-sulfoxide.The hazard of heavy metal on plants has aroused wide concern, heavy metal accumulation affects plant growth and development in plants. Plants gradually formed a series of adaptive mechanism in the process of adaptation to the environment. As a kind of heavy metals with redox properties of heavy metals, Copper (Cu) easily lead to excessive accumulation of plant oxidative stress and reactive oxygen species (ROS). We found a significant increase in the expression of rice methionine sulfoxide reductase (OsMSR) under copper stress used by 2D-PAGE technology in our laboratory. This description OsMSRs of rice showed that OsMSRs may be involved in responding to copper stress in rice.Seven MSR genes were identified in Oryza sativa and we cloned OsMSRA2.1 and OsMSRBS genes from rice, with 564 and 411bp open reading frames, encoding 187 and 136 amino acids, respectively. Their bioinformatics analysis showed that the amino acid sequence encoded by the two genes are highly conserved and both have high homology with SbMSR and ZmMSR..On this basis, tissue expression and induced expression by Copper of the members of rice MSR family were analyzed by Semi RT-PCR. The tissue expression found that OsMSRA2.1 expression was higher in the roots, stems, leaves, and at a low expression level in the seeds. OsMSRA4, OsMSRB1.1 and OsMSRB1.2 expression was higher in stems, leaves, roots and lower in seeds. OsMSRA5 gene expression level was the highest in root while OsMSRB5 was at the highest expression level in leaves. The induced expression by copper indicated that short time Cu stress decreased the expression of OsMSRs, but as stress time went by, the expression of the OsMSRs gene gradually recovered. Moreover, we found that methyl viologen can induce increased expression of OsMSRA2.1 and OsMSRB5 in rice tissues, especially in the roots.Objective to study the growth of transgenic E. coli under Cu and MV stress, we cloned two genes OsMSRA2.1 and OsMSRB5 coding region into the prokaryotic expression vector pET-30a. The recombinant plasmid pET-30a-OsMSRA2.1 and pET-30a-OsMSRB3 were transformed into E. coli BL21 and then induced to express. The recombinant strains was found superior to the control strain, indicating that they gained enhanced tolerance to Cu and MV.For further study of the differences of function between wild type and mutants of OsMSRA2.1 and OsMSRB5, we perchased 1E-01019.L and 3D-00669.R, the mutant of OsMSRA2.1 and OsMSRB5, respectively. Via genotyping of 1E-01019.L and 3D-00669.R, we found that both of the two mutants containing wild. type, heterozygotes and homozygotes, with 3 and 4 homozygotes, respectively. After the identification we moved mutant seedings into the field for better growth and reproduction.