Toxicological responses in halophyte Suaeda salsa to mercury under environmentally relevant salinity

Mercury is a highly risky heavy metal contaminant in intertidal zones in the Yellow River Delta (YRD). Suaeda salsa is a native halophyte in the YRD. In this work, we investigated the toxicological effects of mercury (20 μg L−1) in S. salsa under environmentally relevant salinity (500 mM). The metabolic responses included the increased amino acids and decreased succinate, fructose, glucose, fumarate and ferulate in above-ground part of S. salsa exposed to mercury. The expression levels of INPS, CMO, BADH, CAT and GPx were elevated in above-ground part of S. salsa after combined Hg and salinity exposure. Increased activities of antioxidant enzymes including SOD, POD and CAT were uniquely observed in salinity-treated samples. Our results indicated potential oxidative stresses and disturbances in protein bio-degradation and energy metabolism induced by mercury in S. salsa. Additionally, both synergistic and antagonistic effects were observed in S. salsa exposed to combined mercury and salinity.

► Mercury induced oxidative stresses in S. salsa.
► Mercury disturbed protein bio-degradation and energy metabolism in S. salsa.
► Salinity influenced toxicological responses induced by mercury in S. salsa.
► Both synergistic and antagonistic effects were found between mercury and salinity.