Eco-physiological adaptations of Salsola drummondii to soil salinity: role of reactive oxygen species, ion homeostasis, carbon isotope signatures and anti-oxidant feedback

Physiological and biochemical traits for Salsola drummondii, a habitat-indifferent xerohalophyte, were compared in plants collected from two habitats differing in soil salinity (saline habitat, SH and non-saline habitat, NSH) to understand possible mechanisms of salt tolerance. Samples from different plant organs and soils were collected from the two habitats to assess average leaf fresh and dry weights, leaf succulence (SWC), chlorophyll pigments (Chl a, b, carotenoids), lipid peroxidation (MDA), H2O2 content, antioxidant enzymes activity (catalase, CAT; ascorbate peroxidase, APX and guaiacol peroxidase, GPX), stable carbon isotope composition (delta C-13) and elemental composition. No significant reduction in the leaf biomass and leaf succulence was observed in plants from the two habitat types. We found an increase in activities of antioxidant enzymes (CAT, APX) that would enhance the stress tolerance in plants from the SH. Na+ accumulation in the leaves was significantly greater in plants from SH than in those from NSH. The hyper-accumulation of Na+ didn't impact the concentrations of other essential nutrients. Hydrogen peroxide accumulation was significantly greater in roots than in shoots of plants from SH than in NSH, but there was no difference in shoots. delta C-13 was less negative in SH as compared to NSH. We concluded that S. drummondii is a sodium accumulator and this does not disturb much its normal plant growth. For osmotic adjustment, plants of SH rely more on Na+, but those of NSH rely on proline as osmoregulator. Therefore, S. drummondii may be useful for restoring degraded sodium-affected lands.