Analysis of WRKY Resistance Gene Family in (L.) Gaudich: Crosstalk Mechanisms of Secondary Cell Wall Thickening and Cadmium Stress.

A total of 60 WRKY family genes of ramie were identified in the ramie. The genes were unevenly distributed across 14 chromosomes in the specie and highly concentrated (72%) in the distal telomeric region. Phylogenetic analysis placed these genes into seven distinct subfamilies groups: I, II (a, b, c, d, e), and III, with group IIc containing only the variant of heptapetide sequence (WRKYGKK). Segmental duplication events (41.7%) was found to be the main driver of BnGWRKY evolution. Thirty eight from among the genes showed collinear relationships with WRKY genes from , , and . The number and density of stress and hormone responsives -acting elements were comparably higher than other elements, with abundant ARE and rare LTR -acting elements indicating the long-standing adaptability of ramie to its natural environment. GO and KEGG enrichment analysis of the WRKY target genes revealed their involvement in response to stimuli, immune system processes, transporter protein activity and antioxidant activity. Expression analysis show that most WRKYs were activated by the cadmium stress, more especially the , , BnGWRKY20, and . Combining transcriptome, orthologous gene relationships and qPCR result, we established the possible involvement of and in crosstalk mechanism between secondary cell wall thickening and Cd stress. This provided information into the role of BnGWRKY proteins in ramie secondary wall development and cadmium stress response to, and could serve as basis for improvement of the ramie.