Abstract
The roles of sulfate transporters in the initial uptake, inter-organ transport, and intracellular transport of sulfate in Arabidopsis will be presented in this symposium. The isoforms of sulfate transporter gene family show different kinetic properties and cell-type specific expression. The initial uptake of sulfate in Arabidopsis root involves Sultr1;1 and Sultr1;2 high-affinity transporters expressed in the epidermis, cortex and root hairs. T-DNA insertions in Sultr1;1 and Sultr1;2 significantly restricted the growth, suggesting contribution of these transporters to the acquisition of sulfate in roots. DNA chip analysis of the sultr1;2 mutant showed general symptoms of sulfur deficiencies, indicating that Sultr1;2 is the major component of the sulfate uptake system in roots. Within the cell, sulfate mostly accumulates in the vacuole as an internal pool of sulfur. Sultr4;1 and Sultr4;2 localized at the tonoplast membranes, and disruption of these transporters suggested that they are involved in unloading of sulfate from the vacuole.
