Responses of Puccinellia distans to salinity stress: stress tolerance mechanisms and ecosystem restoration potential.

backgroundSalinity is a major abiotic stressor threatening global agricultural productivity and ecological balance. Understanding the salt tolerance mechanisms in halophytic species can help develop strategies for restoring saline soils and improving crop resilience. Puccinellia distans, a halophytic grass species, serves as a model for exploring adaptive responses to salinity. This study aimed to evaluate the physiological, morphological, and biochemical responses of P. distans to varying salinity levels, assessing its tolerance capacity and potential for use in saline habitat restoration.

resultsSeeds and seedlings of P. distans were exposed to six NaCl concentrations (0, 100, 150, 200, 300, and 400 mM). Increasing salinity significantly reduced germination percentage, germination index, seedling biomass, and shoot and root lengths. At later growth stages, traits such as leaf area, specific leaf area, leaf dry weight, and total biomass exhibited a biphasic response, increasing at 200 mM NaCl and declining thereafter. Photosynthetic pigments, including chlorophylls and carotenoids, increased at 200 mM NaCl, but decreased at 400 mM, reflecting salt stress. Oxidative stress markers, such as malondialdehyde and hydrogen peroxide, peaked at 400 mM NaCl, indicating membrane damage and the accumulation of reactive oxygen species. Osmolytes, such as proline and soluble carbohydrates, accumulated significantly at 200 mM NaCl but declined under extreme salinity, suggesting that stress tolerance mechanisms were overwhelmed. Antioxidant enzyme activities, particularly catalase and ascorbate peroxidase, peaked at moderate salinity, indicating a well-coordinated oxidative defense. Non-Metric Multidimensional Scaling revealed optimal physiological and biochemical adjustments at 150-200 mM NaCl.

conclusionsP. distans demonstrates strong adaptability to salinity at levels of 150-200 mM NaCl through enhanced photosynthetic pigments content, osmotic adjustment, and antioxidant activity. However, extreme salinity imposes significant physiological and biochemical constraints. These findings highlight the species' potential for ecological restoration in saline environments and offer valuable insights into halophyte-based strategies for improving plant performance under salt stress. Future research should focus on elucidating the molecular pathways governing ion transport, osmolyte biosynthesis, and oxidative stress regulation to enhance the species' resilience. Integrating Puccinellia distans into land management practices provides a sustainable approach to enhancing soil stability, productivity, and biodiversity in saline environments.