Diversification and Evolution of Membrane Trafficking Pathways in Plants - How did plants acquire new organelles?

The membrane trafficking system responsible for transporting proteins, lipids, and polysaccharides plays pivotal roles in various plant functions including development, defense responses, intercellular communication, and cell wall biogenesis. This system involves evolutionarily conserved machinery components such as RAB GTPases and SNARE proteins, which regulate tethering and membrane fusion, respectively, between transport vesicles and destination membranes. It is reported that the numbers of genes for these machinery components have been increased during land plant evolution, which could be associated with diversification of membrane trafficking pathways and neofunctionalization and/or acquisition of organelles. For insights into diversification of the membrane trafficking system during land plant evolution, we are conducting comparative analyses of membrane trafficking pathways between Arabidopsis and Marchantia polymorpha. We have systematically identified RAB GTPases and SNARE proteins in M. polymorpha, whose expression patterns, subcellular localizations, and molecular functions are now being investigated. Our latest results on the regulation and functions of RAB GTPases and SNARE proteins will be presented, with special focus on acquisition of novel organelles during evolution.