Root-to-shoot transport of sulfate in Arabidopsis. Evidence for the role of SULTR3;5 as a component of low-affinity sulfate transport system in the root vasculature

Plant Physiol. 2004 Dec;136(4):4198-204. doi: 10.1104/pp.104.045625. Epub 2004 Nov 5.

Abstract

Xylem transport of sulfate regulates distribution of sulfur in vascular plants. Here, we describe SULTR3;5 as an essential component of the sulfate transport system that facilitates the root-to-shoot transport of sulfate in the vasculature. In Arabidopsis (Arabidopsis thaliana), SULTR3;5 was colocalized with the SULTR2;1 low-affinity sulfate transporter in xylem parenchyma and pericycle cells in roots. In a yeast (Saccharomyces cerevisiae) expression system, sulfate uptake was hardly detectable with SULTR3;5 expression alone; however, cells coexpressing both SULTR3;5 and SULTR2;1 showed substantial uptake activity that was considerably higher than with SULTR2;1 expression alone. The V(max) value of sulfate uptake activity with SULTR3;5-SULTR2;1 coexpression was approximately 3 times higher than with SULTR2;1 alone. In Arabidopsis, the root-to-shoot transport of sulfate was restricted in the sultr3;5 mutants, under conditions of high SULTR2;1 expression in the roots after sulfur limitation. These results suggested that SULTR3;5 is constitutively expressed in the root vasculature, but its function to reinforce the capacity of the SULTR2;1 low-affinity transporter is only essential when SULTR2;1 mRNA is induced by sulfur limitation. Consequently, coexpression of SULTR3;5 and SULTR2;1 provides maximum capacity of sulfate transport activity, which facilitates retrieval of apoplastic sulfate to the xylem parenchyma cells in the vasculature of Arabidopsis roots and may contribute to the root-to-shoot transport of sulfate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anion Transport Proteins / physiology*
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / physiology*
  • Biological Transport
  • Gene Expression Regulation, Plant
  • Molecular Sequence Data
  • Organisms, Genetically Modified
  • Plant Roots / metabolism*
  • Plant Shoots / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Sulfates / metabolism*

Substances

  • Anion Transport Proteins
  • Arabidopsis Proteins
  • SULTR3;5 protein, Arabidopsis
  • Sulfates

Associated data

  • GENBANK/AB003591
  • GENBANK/AB061739