Na+/H+antiporter (NHX1) positively enhances cadmium (Cd) resistance and decreases Cd accumulation in tobacco plants cultivated in Cd-containing soil

Aims Na+/H(+)antiporter (NHX1) was reported to be induced by NaCl in plants and NaCl can alleviate the toxic effect in plants caused by cadmium (Cd). However, it is unknown whether theNHX1gene is involved in Cd adaptation in plants. This study aimed to explore the relationship between Cd resistance and NHX1 in plants. Methods SseNHX1gene obtained by shuffling usingSsNHX1fromSuaeda salsaandSeNHX1fromSalicornia europaeaas sequence templates in our previous work, conferred higher salt tolerance to yeast thanSsNHX1andSeNHX1. The overexpression ofSsNHX1,SeNHX1, orSseNHX1genes in tobacco was performed to explore the relationship between Cd resistance andNHX1gene expression in plants. The NHX1 inhibitor amiloride was also used to assess the relationship between Cd resistance and NHX1 in plants. Results Under Cd stress treatment, transgenic tobacco exhibited better growth status, increased chlorophyll content, improved photosynthesis capacity and enhanced content of Na(+)and K(+)compared to wildtype plants. Moreover, transgenic tobacco showed less ROS accumulation, reduced MDA production, and decreased Cd(2+)accumulation compared to WT plants. More importantly, transgenic tobaccos overexpressingSseNHX1gene showed a greater resistance to Cd stress and less Cd accumulation than the transgenic tobaccos overexpressingSsNHX1orSeNHX1genes. Conclusions Cd resistance and Cd accumulation in transgenic tobacco plants was closely correlated with the expression ofNHX1gene.