Differential responses to salinity stress in seedlings of three Eucalyptus Species

Ascorbate and foliar contents of proline, glycine betaine and abscisic acid (ABA) along with lipid peroxidation rates, electrolytic leakage were determined in three different Eucalyptus species, viz. E. camaldulensis Dehn., E. citriodora Hook., E. tereticornis Sm., subjected to salinity stress (Mixed salts: NaCl, MgSO₄ and CaCl₂) of different concentrations (0, 50, 100, 150mM). Sampling was done after 35 days of treatments in leaves. The contents of ascorbate and monodehydroascorbate in the leaf extracts of all Eucalyptus species showed variations to salinity stressed conditions. Lower rates of membrane lipid peroxidation and electrolytic leakage were noticed in the leaves of E. camaldulensis under salinity stress. Quantitative differences were also noticed in foliar proline, glycine betaine and ABA contents among Eucalyptus species in response to salinity. The leaves of E. camaldulensis accumulated more proline, glycine betaine and ABA under salinity stress compared to E. tereticornis and E. citriodora. Our data demonstrate that E. camaldulensis have efficient antioxidative characteristics and ABA accumulation which could provide better protection against oxidative stress in leaves under salinity stress conditions.