WGCNA reveals dosedependent responses and molecular regulatory networks of strigolactonemediated drought mitigation in Astragalus membranaceus mongholicus
Astragalus membranaceus var. mongholicus (Astragalus) is an economically vital medicinal plant whose productivity is severely hindered by drought. This study investigated the concentration dependent effects of strigolactone (0.1, 1, and 10 mol/L) on drought stressed seedlings through integrated physiological and transcriptomic analyses. Results showed that drought induced oxidative damage and inhibited photosynthesis while strigolactone exhibited distinct concentration dependent mitigation. The 0.1 mol/L concentration yielded weak effects due to insufficient signal intensity whereas the high concentration of 10 mol/L strengthened osmotic protection and antioxidant capacity through the Purple module but restricted rapid regeneration by inhibiting protein synthesis and repair. In contrast 1 mol/L strigolactone emerged as the appropriate concentration significantly restoring biomass and photosynthetic efficiency. Mechanistically 1 mol/L strigolactone specifically activated the Turquoise module which is predominantly enriched in ribosome biogenesis and protein processing pathways. The molecular reconstruction of the protein translation machinery was coordinated by a core regulatory cascade involving 12 hub transcription factors, with a notable representation from the WRKY, NAC, and bZIP families. This molecular transition from a stress responsive to a repair growth state effectively blocked damage signals and prioritized functional restoration. These findings validate that appropriate strigolactone levels mitigate drought by restoring protein biosynthetic homeostasis providing a theoretical framework for high quality Astragalus cultivation in arid environments.