Similarities and differences in the physiological adaptation to water salinity between two life forms of aquatic plants in alpine and arid wetlands

Aquatic plants play a crucial role in freshwater ecosystems as primary producers, but their survival is threatened by salinization. Understanding the physiological responses of aquatic plants to increasing water salinity is important for predicting their adaptive strategies under future climate change scenarios. In this study, we measured 15 physiological traits of 49 aquatic plant species along a large environmental gradient in alpine and arid regions of western China to explore their physiological adaptations and compare the similarities and differences in adaptive strategies between emergent and submerged life forms. We found that water salinity and low temperature were key factors affecting aquatic plants in these regions. Aquatic plants adapted to saline habitats by accumulating proline and sulfur (S) concentrations, and to cold habitats by increasing ascorbate peroxidase activity. Plant trait network analysis revealed that S was the hub trait in emergent plants, while proline was the hub trait in submerged plants, indicating that emergent plants balanced osmoregulation and reactive oxygen metabolism through S-containing compounds, while submerged plants prioritized the regulation of osmotic balance through proline.