The universal and divergent roles of ethylene in rice and some other crop plants under salt stress

Soil salinization severely hinders plant growth and decreases crop yield, and is increasingly an obstacle for the sustainability of agriculture. As a stress hormone, ethylene is known to function as a signal molecule to coordinate plant growth and stress response in the dicotyledonous model plant Arabidopsis. However, the roles of ethylene in most crop plants under salinity have received less attention, and underlying mechanisms are still undefined. According to reported results, the functions of ethylene as a stress signal in some crop species like the semiaquatic monocotyledonous plant rice turn out to be much different. Moreover, there exist some contradictions between ethylene production and signaling in salt response. Therefore, in this review, besides making a summary of the universal roles, we also focus on the divergent roles of ethylene under salinity in rice and some other crop species, in terms of ethylene biosynthesis and signal transduction. In addition, the discrepancies between ethylene production and signaling in salt response are discussed.