Abstract
Sulfur is an essential macro-nutrient required for the synthesis of amino acids, proteins and lipids in primary metabolisms. It is usually taken up from soil in the form of sulfate. Uptake and internal transport of major nutrients, such as nitrogen, sulfur and phosphorus, are organized by multiple forms of transporter proteins bearing diversified functions in specific cell-type and organelles. Recent molecular physiological studies have identified the functional properties of plant sulfate transporter family proteins though the aid of functional genomics tools in Arabidopsis. SULTR1;1 and SULTR1;2 were the two essential components of the high-affinity sulfate uptake system at the root surface. The low-affinity subtype, SULTR2;1, was co-localized with SULTR3;5 in the root vasculature, and was functional for root-to-shoot transport. SULTR4;1 and SULTR4;2 facilitate release of sulfate from the vacuoles, controlling sulfate reserve in the root tissues. The function of SULTR1;3 was relevant to the phloem transport of sulfate.
