Light at the end of the tunnel: FRAP assays combined with super resolution microscopy confirm the presence of a tubular vacuole network in meristematic plant cells.

Plant vacuoles play key roles in cellular homeostasis, performing catabolic and storage functions, and regulating pH and ion balance. Despite their essential role, there is still no consensus on how vacuoles are established. A model proposing that the endoplasmic reticulum is the main contributor of membrane for growing vacuoles in meristematic cells has been challenged by a study proposing that plant vacuoles are formed de novo by homotypic fusion of multivesicular bodies (MVBs).

The Arabidopsis V-ATPase is localized to the TGN/EE via a seed plant-specific motif.

The V-ATPase is a versatile proton-pump found in a range of endomembrane compartments yet the mechanisms governing its differential targeting remain to be determined. In Arabidopsis, VHA-a1 targets the V-ATPase to the TGN/EE whereas VHA-a2 and VHA-a3 are localized to the tonoplast. We report here that the VHA-a1 targeting domain serves as both an ER-exit and as a TGN/EE-retention motif and is conserved among seed plants.

The endoplasmic reticulum is the main membrane source for biogenesis of the lytic vacuole in Arabidopsis.

Vacuoles are multifunctional organelles essential for the sessile lifestyle of plants. Despite their central functions in cell growth, storage, and detoxification, knowledge about mechanisms underlying their biogenesis and associated protein trafficking pathways remains limited. Here, we show that in meristematic cells of the Arabidopsis thaliana root, biogenesis of vacuoles as well as the trafficking of sterols and of two major tonoplast proteins, the vacuolar H(+)-pyrophosphatase and the vacuolar H(+)-adenosinetriphosphatase, occurs independently of endoplasmic reticulum (ER)-Golgi and post-Golgi trafficking.