Abstract

The subgroup 9 gene family of R2R3 MYB transcription factors is an ancient gene lineage that arose prior to the origin of the land plants. They have been functionally characterised only within the flowering plants, where they regulate diverse epidermal structures including petal epidermal cell outgrowths, trichome development, and the initiation and elongation of cotton fibres. Broadly, my PhD seeks to understand the ancestral function of these genes, and their subsequent diversification in the mediation of epidermal structures across different land plant lineages. I will first present data on the function of subgroup 9 homologs in the early land plant model Marchantia polymorpha, using semi-quantitative PCR , overexpression and amiRNA knock-down. I will then explore the role of subgroup 9 genes in floral evolution in Nicotiana, where I have used sister species to determine if changes to subgroup 9 gene sequence or expression are associated with shifts in petal cell shape.