Preliminary Study On Drought Resistance Mechanism Of Transcription Factor OsbHLH120 In Rice

Drought severely affected the growth of rice,restricting the sustainable development of rice production.Discovering rice drought resistance genes had important implications to resolve rice drought resistance mechanism and solve the water shortage problem.To further study the funtion of Osb HLH120 gene,the experiment constructed Osb HLHL120 overexpressed transgenic plants and investigated root traits of these plants at 5-6 leaf stage,using PEG6000 to simulate drought stress,investigating physiological changes of plants after PEG stress,combining with transcriptome sequencing data,the results of the study were as follows:1?Under the normal hydroponic conditions,using roots scanner scans root surface area,total root length,root volume,the Maximum root length and average root diameter of each transgenic line in the 5-6 leaf stage,the results showed that the root volume,root length and the longest root volume of transgenic plants generally increase,the results suggested that Osb HLH120 gene was related to these root traits.2?Under the normal hydroponic conditions,using nutrient solution that contains PEG6000 to simulate drought stress,roots were taken at different treatment times of each plant,measuring the expression of Osb HLH120 gene and the content of antioxidant enzymes SOD,POD,CAT of each root,the results showed that the expression of Osb HLH120 gene and the content of antioxidant enzymes both have an increasing trend with the extension of treatment time,and the transgenic plants were higher than the control.Under PEG stress,WT were coerced more seriously,expressing poor performance of plant growth and faster wilt of leaf.The results showed that higher Osb HLH120 gene expression can increase the content of root antioxidant enzyme and strength drought resistance of rice.3?Under the normal conditions,the germination of transgenetic seeds and WT had no difference.But under PEG,salt stress,the germination,root and shoot length of transgenic seeds were significantly higher than the control,the results indicated Osb HLH120 was related to the salt and drought resistance.4?By transcriptome sequencing data analysis,we found that with the higher expression of Osb HLH120 gene,the expression of 408 genes significantly changed in the genome,including 310 upregulated,98 downregulated.In Go gene function annotation,the results showed that the expression of genes that related to antioxidant activity significantly changed in molecular function.analysing the function of the most significant up-and down-regulated 30 genes,the results showed that these genes were most related to the abiotic stress and external stimuli in biological processes,there were some genes involved in root development.By RT-PCR validation of some critical gene,the RT-PCR results were consistent with the results of transcriptome sequencing,Osb HLH120 significantly regulated these gene expression.The results suggested Osb HLH120 may affect the metabolic pathway of rice by regulate the expression of these genes,thus affect the rice root development and drought resistance.5?In order to further clarify the function of the gene Osb HLH120,we constructed RNAi vectors.The Osb HLH120 gene fragment were amplified from the rice genomic DNA.The 400 bp length of interference fragment were connected with the p TCK303 carrier by both directions,from promoters,terminators and Rice Intron structure of p TCK303,we designed two pairs of primers for detecting whether the recombinant vector was successfully constructed.By Agrobacterium-mediated transformation,we got five strains 17 positive Nipponbare transgenic seedlings and detected the expression of Osb HLH120 gene by RT-PCR.The results showed that the expression of Osb HLH120 in three strains had different degrees of decline,indicating that the transgenic plants of Osb HLH120 RNAi interference were successfully constructed,can be used for further experiments.In summary,Osb HLH120 improves rice root length,root diameter by regulating the expression of genes involved in root development.Improving rice drought resistance by regulating the expression of genes related to water transport and synthesis of antioxidant enzymes.