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

Abstract

ABSTRACT 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 Vanilla planifolia, which is an important orchid that is commercially exploited by the food industry for a highly valued flavour, vanillin. V. planifolia 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 VpMADS 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 V. planifolia and paves the path for functional characterisation of selected VpMADS genes in planta and in a heterologous system for managing the commercially important traits in this orchid.