T-DNA tagging-based gain-of-function of OsHKT1;4 reinforces Na exclusion from leaves and stems but triggers Na toxicity in roots of rice under salt stress

Yuuka Oda, Natsuko I. Kobayashi, Keitaro Tanoi, Jian Feng Ma, Yukiko Itou, Maki Katsuhara, Takashi Itou, Tomoaki Horie

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The high affinity K+ transporter 1;4 (HKT1;4) in rice (Oryza sativa), which shows Na+ selective transport with little K+ transport activity, has been suggested to be involved in reducing Na in leaves and stems under salt stress. However, detailed physiological roles of OsHKT1;4 remain unknown. Here, we have characterized a transfer DNA (T-DNA) insertion mutant line of rice, which overexpresses OsHKT1;4, owing to enhancer elements in the T-DNA, to gain an insight into the impact of OsHKT1;4 on salt tolerance of rice. The homozygous mutant (the O/E line) accumulated significantly lower concentrations of Na in young leaves, stems, and seeds than the sibling WT line under salt stress. Interestingly, however, the mutation rendered the O/E plants more salt sensitive than WT plants. Together with the evaluation of biomass of rice lines, rhizosphere acidification assays using a pH indicator bromocresol purple and22NaCl tracer experiments have led to an assumption that roots of O/E plants suffered heavier damages from Na which excessively accumulated in the root due to increased activity of Na+ uptake and Na+ exclusion in the vasculature. Implications toward the application of the HKT1-mediated Na+ exclusion system to the breeding of salt tolerant crop cultivars will be discussed.

Original languageEnglish
Article number235
JournalInternational Journal of Molecular Sciences
Volume19
Issue number1
DOIs
Publication statusPublished - Jan 12 2018

Keywords

  • High affinity K transporter (HKT)
  • Na exclusion
  • Rice
  • Salt stress

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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