Mechanism Analysis Of Receptor-like Kinases Gene OsBAK1L Involved In Regulation Cell Death Response Of Rice(Oryza Sativa L.)

Plant receptor-like kinase(RLK)BAK1(BRI1-associated kinase1), a member of SERK(Somaticembryogenesis receptor kinase) protein kinase family, in Arabidopsis involved in regulation of thediverse physiological processes, including development, responses to microbial signals. There are alarge number of OsSERKs in rice, and many of which are inducible expression by defense signalmolecule abscisic acid(ABA) and pathogen infection. However, few have difinite functions. Xu find ahomologous geneLOC_Os03g49620.4(BRASSINOSTEROID INSENSITIVE1-associated receptorkinase1precursor), which is upregulated expression when inocubated with Xanthomonas oryzaepv.oryzicola (Xoc)Rs105, in a bacterial leaf streak(BLS) disease resistance rice,9804-Rxo1.In the study: we tentatively named LOC_Os03g49620.4as OsBAK1L, and We analyse the aminosequence by using MEGA5.0for multiple sequence alignment, and BioEdit7.1.6.0for sequenceannotation. Then we amplify the coding sequence of the target gene1815bp,according to the sequenceof the LOC_Os03g49620.4, to construct the green fluorescent protein(GFP) vector for subcellularlocation.We choose the specific sequence of the cDNA as the RNAi targer fragment, and construct the RNAivector pB7GWIWG2(II)-OsBAK1L. Transformation to Agrobacterium EHA105by heat shock and thentransform to the9804-Rxo1and get the transgenic rice plant by the select positive calli by herbicide. Weplant the transgenic rice plant,9804-Rxo1and9804, as the positive and negative controls, respectively.We inoculate the plant during the booting stage of rice by pin-prick. And record the change of symptomlast for two weeks. After inoculation to24h,48h,72h,96h,120h sampling to identification theresistance of the transgenic rice plant and foranalysing the expression of HR associated geneOsMPK13(Mitogen activated protein kinase13).OsBAK1L has the similar with the AtSERK family members’ structure, however OsBAK1L is not belongto the OsSERK’ family, due to lack of the SPP motif. OsBAK1L and OsSERL8has the same DNAsequence, but the peptides are different in the exon combinations, they are the different forms ofLOC_Os03g49620’s transcription. In addition, the results of subcellular location indicates thatOsBAK1L is location in the cell membrane, which is the same as the family members of SERKå'ŒSERL.In the study we select OsMPK13gene for expression analysis after the rice plants are inocubated withthe Xanthomonas oryzae pv.oryzicola Rs105. The expression pattern is in a relatively low level in thesusceptible material, and there is almost with little change. When a resistant line,9804-Rxo1, and aOsBAK1L-RNAi transgenic plant, derived from the same9804-Rxo1were inoculate with theXanthomonas oryzae pv.oryzicola Rs105, hypersensibility response (HR) is observed in both of the lines, except that the HR response was slightly delayed in the OsBAK1L-suppresed line. Expressionpattern of a known HR associated gene, OsMPK13(Mitogen activated protein kinase13) was monitoredthat OsMPK13induction was delayed in the OsBAK1L-suppresed line, in the same pattern as the HRresponse.These results suggest that OsBAK1L might control HR in9804-Rxo1through the regulation ofOsMPK13expression.The results of structure analysis indicate that the OsBAK1L protein is a member of SERL (Somaticembryogenesis receptor kinase Like) protein family and located in the cell membrane. RNA expressionshown OsBAK1L is down regulated in OsBAK1L-RNAi transgenic rice plants.