High-affinity H(+)/sulfate cotransporter that mediates the loading of sulfate into the sieve tube. Plays a central role in the regulation of sulfate assimilation. Expressed in the phloem of cotyledons, hypocotyls and roots. In roots and leaves by sulfate starvation. Loss-of-function mutation of the gene result in an attenuation of the source-to-sink transport of sulfate. Belongs to the SLC26A/SulP transporter (TC 2.A.53) family.