Actin-bundling protein fimbrin serves as a new auxin biosynthesis orchestrator in Arabidopsis root tips.

Plants delicately regulate endogenous auxin levels through the coordination of transport, biosynthesis, and inactivation, which is crucial for growth and development. While it is well-established that the actin cytoskeleton can regulate auxin levels by affecting polar transport, its potential role in auxin biosynthesis has remained largely unexplored. Using LC-MS/MS-based methods combined with fluorescent auxin marker detection, we observed a significant increase in root auxin levels upon deletion of the actin bundling proteins AtFIM4 and AtFIM5.

Conserved mechanism for vacuolar magnesium sequestration in yeast and plant cells.

Magnesium (Mg) is an essential nutrient for all life forms. In fungal and plant cells, the majority of Mg is stored in the vacuole but mechanisms for Mg transport into the vacuolar store are not fully understood. Here we demonstrate that members of ancient conserved domain proteins (ACDPs) from Saccharomyces cerevisiae and Arabidopsis thaliana function in vacuolar Mg sequestration that enables plant and yeast cells to cope with high levels of external Mg.

Four plasma membrane-localized MGR transporters mediate xylem Mg loading for root-to-shoot Mg translocation in Arabidopsis.

Magnesium (Mg), an essential structural component of chlorophyll, is absorbed from the soil by roots and transported to shoots to support photosynthesis in plants. However, the molecular mechanisms underlying root-to-shoot Mg translocation remain largely unknown. We describe here the identification of four plasma membrane (PM)-localized transporters, named Mg release transporters (MGRs), that are critical for root-to-shoot Mg transport in Arabidopsis.

Plant Membrane Transport Research in the Post-genomic Era.

Membrane transport processes are indispensable for many aspects of plant physiology including mineral nutrition, solute storage, cell metabolism, cell signaling, osmoregulation, cell growth, and stress responses. Completion of genome sequencing in diverse plant species and the development of multiple genomic tools have marked a new era in understanding plant membrane transport at the mechanistic level. Genes coding for a galaxy of pumps, channels, and carriers that facilitate various membrane transport processes have been identified while multiple approaches are developed to dissect the physiological roles as well as to define the transport capacities of these transport systems.