Physiological and transcriptome characterization provides new insights into mitigation of NaCl stress by strigolactone GR24 in Lycium ruthenicum Murr.

Abstract

Main conclusion: Exogenous strigolactone GR24 effectively alleviates salt stress and enhances the salt tolerance of Lycium ruthenicum Murr. seedlings by improving growth parameters, leaf structure, and chloroplast structural stability, enhancing cell activity, chlorophyll fluorescence, AsA-GSH cycle activity, and activating expression of genes involved in metabolism, signal transduction, and stress resistance pathways. Strigolactones (SLs), a group of carotenoid-derived plant hormones, regulate plant stress tolerance. Lycium ruthenicum Murr., a key native halophyte in northwestern China's arid oasis-desert ecotone with rich nutritional and medicinal value, faces compromised seedling survival under high-salinity alkali conditions despite its role in ameliorating salinized soils and boosting rural economies via artificial cultivation. However, the specific effects and mechanisms of exogenous strigolactone GR24 on L. ruthenicum seedlings under salt stress remain underexplored, representing a critical research gap in stress adaptation. This study utilized hydroponic cultivation to assess the influence of GR24 on L. ruthenicum seedlings exposed to high salinity (250 mM), with a focus on growth parameters, leaf structure, and the AsA-GSH cycle. Results showed that 5 μM exogenous GR24 treatment effectively alleviated salt stress, with significant increases in plant morphological traits, cell activity, and chlorophyll fluorescence compared to untreated seedlings. In addition, GR24 treatment enhanced the activity of the AsA-GSH cycle, effectively scavenging free radicals. Furthermore, 5 μM GR24 treatment improved chloroplast ultrastructure, thereby enhancing subcellular stability and the functionality of the photosynthetic apparatus. Transcriptomic analysis indicated the amount of DEGs of L. ruthenicum by GR24 treatment was enriched in metabolic processes, signal transduction, metabolism, synthesis and resistance. In conclusion, the data offer critical insights into the physiological and molecular mechanisms underlying GR24's role in alleviating salt stress, emphasizing its potential to bolster the salt tolerance of L. ruthenicum.