High Nitrogen Insensitive 9 (HNI9)-mediated systemic repression of root NO 3- uptake is associated with changes in histone methylation

Thomas Widiez, El Sayed El Kafafi, Thomas Girin, Alexandre Berr, Sandrine Ruffel, Gabriel Krouk, Alice Vayssières, Wen Hui Shen, Gloria M. Coruzzi, Alain Gojon, Marc Lepetit

Research output: Contribution to journalArticlepeer-review


In plants, root nitrate uptake systems are under systemic feedback repression by the N satiety of the whole organism, thus adjusting the N acquisition capacity to the N demand for growth; however, the underlying molecular mechanisms are largely unknown. We previously isolated the Arabidopsis high nitrogen-insensitive 9-1 (hni9-1) mutant, impaired in the systemic feedback repression of the root nitrate transporter NRT2.1 by high N supply. Here, we show that HNI9 encodes Arabidopsis INTERACT WITH SPT6 (AtIWS1), an evolutionary conserved component of the RNA polymerase II complex. HNI9/AtIWS1 acts in roots to repress NRT2.1 transcription in response to high N supply. At a genomic level, HNI9/AtIWS1 is shown to play a broader role in N signaling by regulating several hundred N-responsive genes in roots. Repression of NRT2.1 transcription by high N supply is associated with an HNI9/AtIWS1-dependent increase in histone H3 lysine 27 trimethylation at the NRT2.1 locus. Our findings highlight the hypothesis that posttranslational chromatin modifications control nutrient acquisition in plants.

Original languageEnglish (US)
Pages (from-to)13329-13334
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number32
StatePublished - Aug 9 2011


  • Arabidopsis genetics
  • Nitrogen signaling
  • Nutrient uptake
  • Plant chromatin

ASJC Scopus subject areas

  • General

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