Regulatory mechanisms underlying florigenesis in <i>Vanilla planifolia</i> Andrews: A study of MADS-box gene family

Orchid flowers have unique floral organisation which make them indispensable to the floral industry. The MADS-box gene family encodes for transcription factors that are involved mainly in floral organisation. This study was conducted on <i>Vanilla planifolia</i>, which is an important orchid that is commercially exploited by the food industry for a highly valued flavour, vanillin. <i>V. planifolia</i> transcriptome was analysed and 33 MADS-box transcripts that encode putative MADS-box proteins, were identified. Phylogenetic analysis of the VpMADS proteins with other closely related plant species showed clear clustering into type I and type II. Protein characterisation, duplication events, and their evolutionary analysis were performed. The spatio-temporal expression profile for <i>VpMADS</i> genes at different plant developmental stages showed high expression of these genes in specific floral tissues. Secondary and tertiary structural analyses was also done for 13 MADS-box proteins representing each sub-class and their 3D structures were deduced. This study provides a basic understanding of the functioning of MADS-box gene family in <i>V. planifolia</i> and paves the path for functional characterisation of selected <i>VpMADS</i> genes <i>in planta</i> and in a heterologous system for managing the commercially important traits in this orchid.