Salt-alkali tolerant growth-promoting Streptomyces sp. Jrh8-9 enhances alfalfa growth and resilience under saline-alkali stress through an integrative modulation of photosynthesis, antioxidant defense, and hormone response

This study evaluated the effects of Streptomyces sp. Jrh8-9 on alfalfa growth and responses to saline-alkali stress. Jrh8-9 inoculation significantly promoted growth and root nodule formation of stressed alfalfa. It also improved chlorophyll content, maximum photochemical efficiency of photosystem II, and net photosynthetic rate.Transcriptomic profiling identified key differentially expressed genes associated with auxin, jasmonic acid, and abscisic acid signaling in response to Jrh8-9 inoculation, with auxin- and jasmonic acid-related genes linked to antioxidant pathways. These findings highlight the multifaceted mechanisms underlying Streptomyces-induced saline-alkali tolerance.