A WRKY transcription factor WRKY184 from Brassica napus L. is involved in flowering and secondary wall development in transgenic Arabidopsis thaliana

Flowering is one of the important developmental processes, and the timing of flowering can affect seed yield. Lignin is one of the main components of plant cell walls. Lack of lignin in crops will reduce its resistance to stress, which in turn threatens the production of crops. The WRKY transcription factor family is a large family in higher plants and is widely involved in various biological processes. In this study, we isolated the WRKY transcription factorWRKY184fromBrassica napusL. that can simultaneously regulate the development of stems and flowers.BnWRKY184is a member of the IIc subfamily, localized in the nucleus and has no transcriptional activation capability. The tissue expression analysis showed thatBnWRKY184had the highest expression level in stems. Overexpression ofBnWRKY184inArabidopsis thalianaled to early flowering and weaker stem phenotypes. The expression levels of the flowering-related genesFLOWERING LOCUS T,SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1,LEAFYandFRUITFULLwere up-regulated in transgenic plants. The gene expression levels of secondary wall synthesis-related genes, such asNAC SECONDARY WALL THICKENING PROMOTING FACTOR 2,CELLULOSE SYNTHASE 7andCELLLOSE SYNTHASE 8, were down-regulated in transgenic plants. Yeast one-hybrid and promoter-LUC showed thatBnWRKY184can directly bind to the promoter region ofAtNST2and inhibit its expression. Thus,BnWRKY184simultaneously affected plant flowering and secondary wall development by regulating the transcriptional levels of genes involved in both processes, andBnWRKY184can directly regulate the expression ofAtFULandAtNST2, suggesting thatBnWRKY184play roles in certain signaling pathways during plant development.