Plants show varied cellular responses to salinity that are partly associated with maintaining low cytosolic Na+ levels and a high K+/Na+ ratio. Plant metabolites change with elevated Na+, some changes are likely to help restore osmotic balance while others protect Na+-sensitive proteins. Metabolic responses to salt stress are described for two barley (Hordeum vulgare L.) cultivars, Sahara and Clipper, which differed in salinity tolerance under the experimental conditions used. After 3 weeks of salt treatment, Clipper ceased growing whereas Sahara resumed growth similar to the control plants. Compared with Clipper, Sahara had significantly higher leaf Na+ levels and less leaf necrosis, suggesting they are more tolerant to accumulated Na+. Metabolite changes in response to the salt treatment also differed between the two cultivars. Clipper plants had elevated levels of amino acids, including proline and GABA, and the polyamine putrescine, consistent with earlier suggestions that such accumulation may be correlated with slower growth and/or leaf necrosis rather than being an adaptive response to salinity. It is suggested that these metabolites may be an indicator of general cellular damage in plants. By contrast, in the more tolerant Sahara plants, the levels of the hexose phosphates, TCA cycle intermediates, and metabolites involved in cellular protection increased in response to salt. These solutes remain unchanged in the more sensitive Clipper plants. It is proposed that these responses in the more tolerant Sahara are involved in cellular protection in the leaves and are involved in the tolerance of Sahara leaves to high Na+.
Bibliographical noteFunding 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. The authors would like to thank to Dr Tim Sutton for the barley seeds, and Megan Forbes and Suganthi Suren for assistance on GC-MS. Widodo was a recipient of the Melbourne International Fee Remission Scholarship (MIFRS) and Islamic Development Bank Merit Scholarship Program for High Technology (IDB-MSP).
- Salt stress
- Tissue tolerance
ASJC Scopus subject areas
- Plant Science