Strigolactone and salicylic acid simultaneously enhance the resilience of common bean against salt stress by strengthening the antioxidant defense system

Salinity is a major abiotic stress that greatly reduces crop yields worldwide. The common bean is especially vulnerable to damage from salinity. In this study, we examined the physiological and molecular responses of salt-stressed common bean plants to foliar applications of salicylic acid (SA) and the synthetic strigolactone analogue GR24. Salt stress increased electrolyte leakage and proline levels while decreasing relative water content, total protein, and photosynthetic pigments. Applying either SA or GR24 alone improved tolerance, but using both together provided even greater protection, mainly by reducing electrolyte leakage. Both treatments boosted antioxidant enzyme activities, such as ascorbate peroxidase, superoxide dismutase, and catalase, by promoting protein synthesis or preventing degradation. The combined use of SA and GR24 partially restored photosynthetic pigment levels under salinity. The expression of SOD, CAT, APX, and GPX genes was upregulated in plants treated with both SA and GR24 under salt stress, emphasizing the role of these enzymes in maintaining redox balance and stress tolerance. Overall, SA and GR24 (1 mM SA + 10 µM GR24) worked together to enhance bio-physiological and metabolic functions under salinity, offering a promising strategy to support plant recovery.