Ethylene as a gas phytohormone plays significant roles in the whole life cycle of plant, ranging from growth and development to stress responses. A linear ethylene signaling pathway has been established in dicotyledonous model plant Arabidopsis. However, the ethylene signaling mechanism in monocotyledonous plants such as rice is largely unclear. In this review, we compared the ethylene-response phenotypes of dark-grown seedlings of Arabidopsis, rice and other monocotyledonous plants (maize, wheat, sorghum andBrachypodium distachyon), and found that rice had a distinct phenotype of root inhibition but coleoptile promotion in etiolated seedlings upon ethylene treatment. We further summarized the homologous genes ofArabidopsis ethylene signaling components in these monocotyledonous plants and evaluated the recent progresses involved. Though conserved in most aspects, ethylene signaling in rice has new features compared with that in Arabidopsis. These analyses provide novel insights into the understanding of ethylene signaling in dicotyledonous Arabidopsis and the monocotyledonous plants, particularly rice. Further characterization of rice ethylene-response mutants and their corresponding genes will help to clarify the whole picture of ethylene signaling mechanisms in plants.

Key words:Ethylene response; signaling; Arabidopsis; rice; monocotyledonous plants; crosstalk