Complementary protective effects of autophagy and antioxidative activity on salt tolerance in Suaeda salsa seedlings

Soil salinity is a major concern for agricultural productivity worldwide. The halophyte Suaeda salsa can survive in saline environments, and the timely removal of reactive oxygen species (ROS) by plants is critical for enhancing salt tolerance. However, the mechanisms underlying salt tolerance in S. salsa remain unclear. In this study, we investigated the relationships among autophagy, antioxidant enzyme activity, and ROS accumulation in S. salsa under salt stress. The root/shoot ratio of S. salsa desreased as salt concentration increased, whereas dry weight and polysaccharide content remained relatively high under saline conditions. Under 200 mM sodium chloride treatment, S. salsa exhibited the strongest superoxide anion radical and hydroxyl radical scavenging capacities, along with the lowest H 2 O 2 content. Transmission electron microscopy revealed basal autophagy under 200 mM sodium chlorid. Superoxide dismutase activity remained high under salt stress, while the activities of catalase and peroxidase were highest in the salt-free control. Transcriptome analysis showed that the expression profiles of key genes were broadly consistent with changes in enzyme activity and autophagy. Correlation analysis further indicated that both antioxidant enzyme activity and autophagy were associated with free radical scavenging. Superoxide anion radical scavenging ability was negatively correlated with Atg8 , Pod , and Cat ; hydroxyl radical scavenging ability was positively correlated with Sod , and H 2 O 2 content was positively correlated with Cwm . Our findings suggest that autophagy and antioxidative enzymes act in a coorrdinated protective network during S. salsa adaptation to salt stress, providing a theoretical foundation for future work on regulating salt tolerance.