Abstract
The Arabidopsis genome contains 14 genes encoding sulfate transporters. Sulfate transporter, Sultr1;3 belongs to the family of high-affinity transporters, and was able to complement the sulfate uptake capacity of the yeast sulfate transporter mutant. Cell-type specificity of Sultr1;3 was studied in transgenic Arabidopsis expressing the fusion protein of Sultr1;3 and green fluorescent protein (GFP) under the control of Sultr1;3 promoter. Sultr1;3-GFP specifically localized in the phloem of cotyledons, hypocotyls and roots. Sultr1;3 mRNA accumulated under low-sulfur conditions. Inter-organ movement of 35S sulfate was determined in the T-DNA insertion mutant of Sultr1;3. In this mutant, the efficiency of the movement of sulfate from cotyledons to the other organs was approximately 30 % of the wild type. These results suggest that Sultr1;3 participates in the loading of sulfate to the sieve element-companion cell complex and controls the inter-organ movement of sulfate in Arabidopsis.
