Investigation of the effect of melatonin and endofithic bacteria administration on salt stress tolerance in gazal neck (lotus corniculatus) plants in vitro conditions

The use of natural antioxidants such as melatonin and plant growth-promoting endophytic bacteria in improving plant stress responses is among the promising strategies for sustainable agriculture. This study aimed to investigate the effects of combined application of melatonin and endophytic bacteria on salt (NaCl) stress tolerance in Lotus corniculatus (bird's-foot trefoil) under in vitro conditions. L. corniculatus plants, grown under sterile conditions, were subjected to treatments including 1 and 5 mM melatonin, 75 and 100 mM NaCl, endophytic bacteria isolated from cacti, and combinations of these treatments. Morphological and physiological parameters (root and shoot length, fresh and dry biomass) as well as biochemical responses (malondialdehyde, reducing sugar, H₂O₂, and proline levels) were analyzed. In addition, the expression levels of stress-related NAC and SOS genes were determined using real-time PCR (RT-PCR). The combined application of melatonin and endophytic bacteria enhanced plant growth and strengthened antioxidant defense mechanisms. The findings suggest that the combination of melatonin and endophytic bacteria may serve as an effective biological protection strategy against salt stress in forage crops such as L. corniculatus.