In silico identification, characterization and expression profile of WUSCHEL-related homeobox (WOX) gene family in Vanilla planifolia

Vanilla planifolia is an economically important orchid, which is being commercially exploited by the food industry for the highly valued secondary metabolite vanillin. WUSCHEL-related homeobox (WOX) gene family encodes for WUSCHEL-related homeobox (WOX) transcription factors that participate in embryogenesis, organogenesis and florigenesis and in diverse plant developmental processes as well. In the present study, we analysed V. planifolia transcriptome and identified 6 WOX (VpWOX) transcripts, that encode putative WOX (VpWOX) transcription factor proteins. Domain analysis was done which indicates the presence of helix-loop-helix-turn-helix which is identifying feature of WOX gene family proteins. We executed phylogenetic clustering for the VpWOX proteins with their counterpart from the model plant Arabidopsis thaliana (AtWOX) and other closely related orchid species, Phalaenopsis equestris (PeWOX), Dendrobium catenatum (DcWOX) and Apostasia shenzhenica (AsWOX) and established their clade specific grouping. Spatio-temporal expression profile for VpWOX genes was analysed for different plant developmental stages which shows that VpWOX13 is expressing uniformly in all the developmental stages whereas, other genes have tissue specific expression. Based on gene expression patterns, we selected four VpWOX proteins and carried out secondary and tertiary structural analysis which indicates the presence of alpha helix and beta turn in the protein structure. The present study provides basic understanding of the functioning of WOX gene family in V. planifolia and paves the path for functional characterization of selected VpWOX genes in planta and in heterologous system in future for commercial utilization.