Arabidopsis thaliana is a small flowering plant that is widely used as a model organism in plant biology. We describe here the Ethylene-Response Pathway (Ethylene- Pathway) whose is belong to the signal transduction pathways. The knowledge of the signaling pathways are still incomplete and discrete modelling has been shown to help a better understanding of the underlying mechanisms. In this paper we provide a brief introduction to the Ethylene- Pathway and describe two approaches - UML-Statecharts and Life Sequence Charts (LSC) - in discrete modelling of the signaling pathway.