Studies On The Expression Pattern Of PagLEA51 Gene In Response To Salt Stress In Populus Alba×P.glandulosa

LEA（late embryogenesis abundant）protein,since it was first discovered in cotton,has been found in the plant kingdom from simple algae,mosses,ferns to angiosperms.LEA protein may contain many deembryoprotectants and plays a key role in plant resistance to stress environment,but the mechanism of its stress response in poplar was seldom studied.In this study,Populus alba×P.glandulosa was used as the experimental material,the PagLEA51 gene was cloned,and its expression pattern in response to abiotic stress was analyzed.To lay the foundation for elucidating the function of PagLEA51 protein and the mechanism of defense response,the specific results are as follows:The cDNA fragment of PagLEA51 gene was cloned from Populus alba×P.glandulosa,which was 714bp in length and encoded 237 amino acid residues.After analysis,it was found that the theoretical isoelectric point of PagLEA51 protein was 5.11,the relative molecular mass was 60.06803ku;the grand average of hydropathicity was 0.886,and the instability index was47.86.The protein was considered to be an unstable hydrophobin.The PBI121-PagLEA51-GFP expression vector was constructed and injected into tobacco cells by the method of transient transformation of tobacco.It was found that the protein was located in the nucleus.The fusion vector p GBKT7-PagLEA51 was constructed and transferred into yeast competent cells,and it was found that the gene did not have transcriptional activation activity.The results of RT-q PCR showed that the expression of PagLEA51 gene was tissue-specific,and its expression level was the highest in roots,and the gene was induced by salt stress.The expression levels in each tissue showed a trend of increasing first and then decreasing,and the expression level in leaves was the highest.The promoter sequence upstream of the PagLEA51 gene was cloned,and it was found that the promoter sequence contained a variety of cis-acting elements,such as salt stress drought stress response elements,gibberellin response elements and so on.The PagLEA51 gene overexpression vector was constructed,and the Populus alba×P.glandulosa was genetically transformed by the methods of genetic transformation,and the overexpression line was cultivated.Under the treatment of salt stress,the lines overexpressing the PagLEA51 gene showed good resistance,and the growth state was significantly better than that of the wild-type plants.The POD,SOD activity and proline content of the transgenic plants were higher than those of the wild type;The contents of MDA and H₂O₂ were lower than those of the wild type.It shows that the transgenic plants can enhance the stress resistance ability of transgenic plants by enhancing the scavenging ability of reactive oxygen species and the accumulation of proline.