Abstract:The effects of endogenous ethylene on plant salt tolerance in Arabidopsis seedlings in exposure to salinity were investigated in the present work. The results showed that 100 mmol·L-1 NaCl significantly decreased seedling root elongation and root fresh weight. Application of exogenous ethephon obviously alleviated salt-induced inhibition of root length and biomass accumulation. Comparatively, exogenous ACC had a positive effect merely on alleviating root weight inhibition caused by salt stress. The root ROS level in salt-stressed seedlings was also increased drastically, and both ethephon and ACC could keep the root ROS level at a low level as control under NaCl stress conditions. It was proposed that improvement of Arabidopsis salt tolerance induced by ethylene is tightly related to root redox state.