Involvement of polyamines, abscisic acid and anti-oxidative enzymes in adaptation of Blue Panicgrass (Panicum antidotale Retz.) to saline environments

A hydroponic experiment was conducted to assess the possible involvement of polyamines (PAs), abscisic acid (ABA) and anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in adaptation of six populations of Panicum antidotale Retz. to selection pressure (soil salinity) of a wide range of habitats. Plants of six populations were collected from six different habitats with ECe ranging from 3.39 to 19.23 dS m⁻¹ and pH from 7.65 to 5.86. Young tillers from 6-month-old plants were transplanted in plastic containers each containing 10 l of half strength Hoagland's nutrient solution alone or with 150 mol m⁻³ NaCl. After 42 days growth, contents of polyamines (Put, Spd and Spm) and ABA, and the activities of anti-oxidative enzymes (SOD, POD and CAT) of all populations generally increased under salt stress. The populations collected from highly saline habitats showed a greater accumulation of polyamines and ABA and the activities of anti-oxidative enzymes as compared to those from mild or non-saline habitats. Moreover, Spm/Spd and Put/(Spd + Spm) ratios generally increased under salt stress. However, the populations from highly saline environments had significantly higher Spm/Spd and Put/(Spd + Spm) ratios as compared to those from mild or non-saline environments. Similarly, the populations adapted to high salinity accumulated less Na⁺ and Cl⁻ in culm and leaves, and showed less decrease in leaf K⁺ and Ca²⁺ under salinity stress. Higher activities of anti-oxidative enzymes and accumulation of polyamines and ABA, and increased Spm/Spd and Put/(Spm + Spd) ratios were found to be highly correlated with the degree of adaptability of Panicum to saline environment.