PLoS Genetics (Sep 2016)

Nuclear Localised MORE SULPHUR ACCUMULATION1 Epigenetically Regulates Sulphur Homeostasis in Arabidopsis thaliana.

  • Xin-Yuan Huang,
  • Dai-Yin Chao,
  • Anna Koprivova,
  • John Danku,
  • Markus Wirtz,
  • Steffen Müller,
  • Francisco J Sandoval,
  • Hermann Bauwe,
  • Sanja Roje,
  • Brian Dilkes,
  • Rüdiger Hell,
  • Stanislav Kopriva,
  • David E Salt

DOI
https://doi.org/10.1371/journal.pgen.1006298
Journal volume & issue
Vol. 12, no. 9
p. e1006298

Abstract

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Sulphur (S) is an essential element for all living organisms. The uptake, assimilation and metabolism of S in plants are well studied. However, the regulation of S homeostasis remains largely unknown. Here, we report on the identification and characterisation of the more sulphur accumulation1 (msa1-1) mutant. The MSA1 protein is localized to the nucleus and is required for both S-adenosylmethionine (SAM) production and DNA methylation. Loss of function of the nuclear localised MSA1 leads to a reduction in SAM in roots and a strong S-deficiency response even at ample S supply, causing an over-accumulation of sulphate, sulphite, cysteine and glutathione. Supplementation with SAM suppresses this high S phenotype. Furthermore, mutation of MSA1 affects genome-wide DNA methylation, including the methylation of S-deficiency responsive genes. Elevated S accumulation in msa1-1 requires the increased expression of the sulphate transporter genes SULTR1;1 and SULTR1;2 which are also differentially methylated in msa1-1. Our results suggest a novel function for MSA1 in the nucleus in regulating SAM biosynthesis and maintaining S homeostasis epigenetically via DNA methylation.