Cloning And Functional Analysis Of CsWRKY50 In Cucumber

Cucumber downy mildew is the most devastating worldwide disease in the production of melon vegetables,which causes very serious losses.Therefore,study of the mechanisms of resistance to downy mildew and resistant gene expression in cucumber is important.In this study,the differential expression gene CsWRKY50 was discovered through the induction of downy mildew and transcriptome data.The defense mechanism of the gene to cucumber downy mildew was studied in order to enrich the theoretical basis of cucumber downy mildew resistance mechanism.The main findings are as follows:A differentially expressed gene was identified by the induction of downy mildew fungus and transcriptome data,and the relationship between the gene structure and other species related genes was clarified through the analysis of evolutionary tree and gene sequence comparison.It was found that it has high homology with AtWRKY50,the gene was named CsWRKY50.Subcellular localization test showed that the gene encoded nuclear localization protein.It was found that the expression of the gene was higher in female flowers,leaves and roots.Real-time fluorescence quantitative PCR assay showed that the expression of CsWRKY50 was affected by adversity stresses,3 h was induced and 6 h to the highest value under drought induction;salt induction,6 h was induced and the expression of 12h was the highest;and other hormones MeJA,SA,ABA and BR were processed,1 h began to be expressed,and the expression levels changed correspondingly at the later stage.The results suggested that CsWRKY50 may play an important role in stress response.The genetic transformation of cucumber was carried out,the results showed that compared with WT,the lesion area of the transgenic strain was significantly decreased after inoculation with downy mildew.After the detection of H₂O₂ or O₂^-content,some active oxidase and the expression of oxidase transcription factor,the expression of CsWRKY50 has been found to improve the scavenging ability of reactive oxygen species.It was found that both SA and JA-mediated Mark and synthetic gene expression pathways were changed,and SA synthetic genes were significantly upregulated,such as PAL and PR1 expression was significantly higher than WT after the inoculation of downy mildew.In addition,the expression of some defense-related genes increased significantly,indicating that the expression CsWRKY50 induce SA synthesis and defense gene expression to enhance the resistance of cucumber to downy mildew.