ABSTRACT
WRKY, a class of conserved transcription factors in plants, plays important roles in plant growth, development and secondary metabolism. In the present study, 65 WRKY members were identified from de novo transcriptome sequencing data of three different tissues (root, stems and leaves) of Baphicacanthus cusia. BcWRKY proteins contained from 221 to 706 amino acids and the isoelectric point is from 4.68 to 9.68. Molecular weights range from 25 711.8 to 75 475 Da. The main secondary structures of BcWRKYs protein are random coil. A subcellular localization prediction indicated that the putative BcWRKY proteins were enriched in the nuclear region. Phylogenetic analysis showed that BcWRKYs could be categorized into three groups and five subgroups (Group IIa, Group IIb, Group IIc, Group IId and Group IIe) in Group II. Structural analysis found that all BcWRKY proteins contained a highly conserved motif WRKYGQK. Finally, the transcriptional profiles of ten BcWRKY genes highly expressed in root, stem and leaf tissues under abscisic acid (ABA), methyl jasmonate (MeJA), or salicylic acid (SA) treatment were systematically investigated using qRT-PCR analysis. Results showed that a total of ten BcWRKY genes were differentially expressed in response to ABA, MeJA, and SA treatment. This work would be provided a basis for further elucidating the molecular mechanism of WRKY transcription factors in the biosynthesis of indole alkaloids in B. cusia.