Ethylene signaling in plants

• Published in: The Journal of biological chemistry Vol. 295; no. 22; pp. 7710 - 7725
• Main Author: Binder, Brad M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 29.05.2020; American Society for Biochemistry and Molecular Biology
• Subjects: Arabidopsis thaliana; bioengineering; constitutive triple response 1 (CTR1); Endoplasmic Reticulum - genetics; Endoplasmic Reticulum - metabolism; ethylene; ethylene-insensitive 2 (EIN2); Ethylenes - metabolism; Gene Expression Regulation, Plant - physiology; hormone receptor; Intracellular Membranes - metabolism; JBC Reviews; phytohormone; Plant Growth Regulators - metabolism; plant hormone; Plant Proteins - genetics; Plant Proteins - metabolism; Plants - genetics; Plants - metabolism; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Response Elements - physiology; signal transduction; Signal Transduction - physiology; signaling; Transcription Factors - genetics; Transcription Factors - metabolism; Arabidopsis thaliana; plant hormone; ethylene-insensitive 2 (EIN2); signaling; signal transduction; constitutive triple response 1 (CTR1); hormone receptor; ethylene; bioengineering; phytohormone
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.REV120.010854

Ethylene is a gaseous phytohormone and the first of this hormone class to be discovered. It is the simplest olefin gas and is biosynthesized by plants to regulate plant development, growth, and stress responses via a well-studied signaling pathway. One of the earliest reported responses to ethylene is the triple response. This response is common in eudicot seedlings grown in the dark and is characterized by reduced growth of the root and hypocotyl, an exaggerated apical hook, and a thickening of the hypocotyl. This proved a useful assay for genetic screens and enabled the identification of many components of the ethylene-signaling pathway. These components include a family of ethylene receptors in the membrane of the endoplasmic reticulum (ER); a protein kinase, called constitutive triple response 1 (CTR1); an ER-localized transmembrane protein of unknown biochemical activity, called ethylene-insensitive 2 (EIN2); and transcription factors such as EIN3, EIN3-like (EIL), and ethylene response factors (ERFs). These studies led to a linear model, according to which in the absence of ethylene, its cognate receptors signal to CTR1, which inhibits EIN2 and prevents downstream signaling. Ethylene acts as an inverse agonist by inhibiting its receptors, resulting in lower CTR1 activity, which releases EIN2 inhibition. EIN2 alters transcription and translation, leading to most ethylene responses. Although this canonical pathway is the predominant signaling cascade, alternative pathways also affect ethylene responses. This review summarizes our current understanding of ethylene signaling, including these alternative pathways, and discusses how ethylene signaling has been manipulated for agricultural and horticultural applications.