Contribution of Rhizobium–Legume Symbiosis in Salt Stress Tolerance in Medicago truncatula Evaluated through Photosynthesis, Antioxidant Enzymes, and Compatible Solutes Accumulation

The effects of salt stress on the growth, nodulation, and nitrogen (N) fixation legumes are well known, but relationship between symbiotic (SNF) driven by rhizobium–legume symbiosis tolerance in Medicago truncatula is not studied. active nodulation process were evaluated quantifying compatible solutes, soluble sugars, antioxidants enzymes, as growth survival rate plants. Eight weeks old plants, divided three groups: (i) no nodules (NN), (ii) inactive (IN), (iii) (AN), exposed to 150 mM NaCl for 0, 8, 16, 24, 32, 40, 48 h hydroponic system. AN plants showed a higher (30.83% 38.35%), chlorophyll contents (37.18% 44.51%), photosynthesis compared IN NN respectively. Improved was linked with activities enzymatic nonenzymatic K+ (20.45% 39.21%) lower Na+ accumulations (17.54% 24.51%) when Additionally, generation reactive oxygen species (ROS) indicative stress, causing membrane damage revealed electrolyte leakage lipid peroxidation. All such significantly ameliorated showing solutes (proline, free amino acids, glycine betaine, proteins) maintaining relative water (61.34%). This study advocates positive role Rhizobium meliloti inoculation against through upregulation antioxidant system concentration solutes.