Cloning And Functional Analysis Of OsCOA Related To Rice Root Nematode Resistance Gene In Rice

Rice(Oryza sativa)is an important grain crop in China.It is of great significance tomaintain a stable sown area,a steady increase in yield,and further improvement in quality and safety.And it is beneficial toincrease farmers’ income,continuously consolidate the achievements in overcoming poverty,ensure national food security,and promote the modernization of agriculture and rural areas.Plant diseases are one of the main limiting factors for the production of food crops,the realization of food security and food safety.Among a variety of plant pathogens,plant nematodes cause a reduction in grain crop yields of about 5-20%.As an important component of rice,lignin plays an essential role in mechanical support,water conduction and disease resistance.A large number of studies have shown that when plants are attacked by external organisms or non-organisms,they will induce the increase of lignin content,thereby promoting the lignification of plant cell walls and forming a mechanical barrier.Caffeoyl-coenzyme 3-O-methyltransfer(CCoAOMT)is a vital methyl enzyme in lignin biosynthesis.CCoAOMT gene has been cloned from many plants and verified that the content of CCoAOMT can affect the changes of lignin composition and content.There are alsomany studies that have confirmed the CCoAOMT participated in plant stress response.In this study,an up-regulated gene,CCoAOMT,was selected from the transcriptome data of rice varieties with resistance torice root nematodes.For further research on the mechanism and function of this gene.The CCoAOMT gene was cloned from total RNA in root of O.sativa,which was named as Os COA gene(Gen Bank: MW812350).The preliminary structural and conservative domain analysis of the gene using bioinformatics confirmed that it belonged tothe CCoAOMT family.The prokaryotic expression vector of Os COA was constructed toexpress Os COA recombinant protein.And a large amount of soluble Os COA protein was successfully induced in vitroat 18°C for 8 hours with the 0.1m M IPTG,which made a base for continuing tofind the protein interacting with it and analyzing the function of Os COA gene in anti-nematode.The expression vector and the interference vector were successfully constructed,and the corresponding transgenic plants were obtained.q RT-PCR analysis showed that the expression of Os COA gene increased significantly in the over-expressed rice.And there were differences in expression in different tissues,with the highest expression in roots,followed by stems.In order toexplore the anti-nematode mechanism of transgenic rice expressing the gene,rice was infected with rice root nematodes for one week.The expression level of over-expression rice roots showed a sharp increase,which was extremely significantly higher than that of other tissues.Furthermore,the infection level of rice root nematode in over-expression plants dropped by 18%.According tothe difference in the expression of rice Os COA gene,we speculated that it played an important role in the prevention and control of rice root nematode disease.And it is expected toprovide an important basis for the prevention and control of rice root nematodes and the in-depth study on the resistance mechanism.