Structure And Functional Analysis Of OsLRK2 In Rice

OsNox2(NADPH oxidase,Nox)is related to the metabolic regulation of reactive oxygen species(ROS).Previously,we have identified two genes,which were co-expressed with Os Nox2.The genes were named OsLRK2(Leucine-rich repeat kinase,LRK)and Os RLCK267(receptor-like cytoplasmic kinase,RLCK).This paper researched the biological functions of OsLRK2 through a series of methods.The main results are as follows:1)Structure and evolution analysis of OsLRK2: Genes close to the OsLRK2 were similar to the structure of OsLRK2,we find that they were homologous genes and very close to evolution,proving that OsLRK2 is located in a gene cluster containing 8 genes.It was found that 36 proteins were homologous to OsLRK2,and a phylogenetic trees was built.The OsLRK2 was highly homologous with arabidopsis thaliana At FRK1(FLG22-INDUCED RECEPTOR-LIKE KINASE 1)and At IOS1(IMPAIRED OOMYCETE SUSCEPTIBILITY1).Both At FRK1 and At IOS are LRK locate on the plasma membrane,and both participate in the defense process of plants.Then,the secondary structure of OsLRK2 was plotted,a relatively definite ATP binding site in the intracellular domain of OsLRK2 was found,and there are only one LRR motif was contained outside the plasmalemma.The tertiary structure prediction of the OsLRK2 showed that it is similar with the protein model ‘2qkw.1.B’,and the interactive key sites of the OsLRK2 were predicted at the 251-255 position amino acids2)OsLRK2’s biological function analysis: Multiple hormones and stress treatments were applied to rice seedlings,and the expression of OsLRK2 gene was analyzed by q RT-PCR.The results showed that the OsLRK2 expression was significantly up-regulated at 6or 9 hours,indicating that OsLRK2 may be involved in ABA,drought resistance and GA-related regulatory processes.Through the identification of OsLRK2 and Os RLCK267 transgenic plants and the quantitative analysis of Os RLCK267 and OsLRK2,the experiment indicates that the expression of OsLRK2 is not affected by the up-regulated and down-regulated Os RLCK267 expression,while Os RLCK267 is strongly influenced by the down-regulated OsLRK2 expression.The phenotypic analysis of the OsLRK2 silencing transgenic plant was found that the silencing of the OsLRK2 resulted in short plant,reduced germination percentage,shorter leaves,reduced leaf area,internodes shorter and slow internodes differentiation.The OsLRK2 silenced transgenic plants’ survival rate were lower after drought stress.The OsLRK2 silenced plants were more sensitive to drought response.DAB,NBT results and hydrogen peroxide measure results showed that the silencing of the OsLRK2 would result in a lack of response to the drought.The results of hormone treatment phenotype experiments showed that OsLRK2 silencing plants were sensitive to GA treatment at 20 mg/L concentration.OsLRK2 silencing plants have a more blunt sense to BR treatment,and the BR of 0.005 mg/L may promote the second stem segment differentiation of the plant.To summaries,the analysis of the bioinformatics survey,gene quantitative analysis and the phenotypic analysis of the OsLRK2 and OsLRK2 silencing transgenic plant indicted that the OsLRK2 is a leucine-rich protein kinase that is involved in the development of rice development with close relationship in the GA,ABA regulation drought responses.