Membrane Delivery to the Vacuole and the Multifunctional Roles of Vacuoles

The vacuole is the largest organelle in plants and provides various crucial functions to plant cells. This book chapter recapitulates the multifunctional roles of plant vacuoles and mainly focuses on the highly dynamic vacuolar morphology. Vacuolar appearance and function differ depending on the cell type and its developmental stage. Lytic vacuoles (LVs) are the most common vacuoles in vegetative tissues. They display an acidic pH and contain proteinases as well as nucleases to fulfil their function as a part of the degradation machinery. The so-called protein storage vacuoles (PSVs) mainly occur in seed tissues and can be converted into LVs during development. Besides discussing the multiple roles of the vacuoleVacuoles, we review how distinct vesicleVesicles traffickingTrafficking routes define the identity and, thereby, function of the vacuolar membraneMembrane (also called tonoplast). Sorting signals and receptors define the specific delivery of cargo vesiclesVesicles, which require a complex interplay of vesicleVesicles coats, tethering factors, as well as membrane fusion machinery. Vacuolar size and the overall size of the cell are coordinated, which plays a pivotal role in cell size determination. The vacuolar volume increases during cellular elongationElongation and thereby allows the cytosolic volume of the cell to remain relatively constant. Here we highlight that plant cells use a complex network of vesicleVesicles traffickingTrafficking routes to precisely coordinate cargo delivery to the tonoplast, as well as, the overall size of the vacuoleVacuoles.