Characterization of ion contents and metabolic responses to salt stress of different arabidopsis AtHKT1;1 genotypes and their parental strains

Camilla B. Hill, Deepa Jha, Antony Bacic, Mark Tester, Ute Roessner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

Plants employ several strategies to maintain cellular ion homeostasis under salinity stress, including mediating ion fluxes by transmembrane transport proteins and adjusting osmotic pressure by accumulating osmolytes. The HKT (high-affinity potassium transporter) gene family comprises Na+ and Na+/K+ transporters in diverse plant species, with HKT1;1 as the only member in Arabidopsis thaliana. Cell-type-specific overexpression of AtHKT1;1 has been shown to prevent shoot Na+ overaccumulation under salinity stress. Here, we analyzed a broad range of metabolites and elements in shoots and roots of different AtHKT1;1 genotypes and their parental strains before and after salinity stress, revealing a reciprocal relationship of metabolite differences between an AtHKT1;1 knockout line (hkt1;1) and the AtHKT1;1 overexpressing lines (E2586 UASGAL4:HKT1;1 and J2731*UASGAL4:HKT1;1). Although levels of root sugars were increased after salt stress in both AtHKT1;1 overexpressing lines, E2586 UASGAL4:HKT1;1 showed higher accumulation of the osmoprotectants trehalose, gentiobiose, and melibiose, whereas J2731*UAS GAL4:HKT1;1 showed higher levels of sucrose and raffinose, compared with their parental lines, respectively. In contrast, the knockout line hkt1;1 showed strong increases in the levels of the tricarboxylic acid (TCA) cycle intermediates in the shoots after salt treatment. This coincided with a significant depletion of sugars, suggesting that there is an increased rate of carbon influx into the TCA cycle at a constant rate of C-efflux from the cycle, which might be needed to support plant survival during salt stress. Using correlation analysis, we identified associations between the Na+ content and several sugars, suggesting that regulation of sugar metabolism is important in plant responses to salinity stress.

Original languageEnglish (US)
Pages (from-to)350-368
Number of pages19
JournalMolecular plant
Volume6
Issue number2
DOIs
StatePublished - Mar 2013

Bibliographical note

Funding Information:
This work was funded by grants to the Australian Centre for Plant Functional Genomics (ACPFG) from the Australian Research Council (ARC) and the Grains Research and Development Corporation (GRDC), the South Australian Government, and the University of Adelaide, the University of Queensland, and the University of Melbourne. C.B.H. is a recipient of the Melbourne International Fee Remission Scholarship (MIFRS), Melbourne International Research Scholarship (MIRS), and the University of Melbourne Special Postgraduate Studentship.

Keywords

  • Abiotic stress
  • HKT
  • enhancer trap system
  • salinity
  • salt tolerance
  • sodium transporter, metabolomics

ASJC Scopus subject areas

  • Molecular Biology
  • Plant Science

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