The regulation of ACC synthase protein turnover: a rapid route for modulating plant development and stress responses

The phytohormone ethylene regulates plant growth, development, and stress responses. The strict fine-tuning of the regulation of ethylene biosynthesis contributes to the diverse roles of ethylene in plants. Pyridoxal 5′-phosphate–dependent 1-aminocyclopropane-1-carboxylic acid synthase, a rate-limiting enzyme in ethylene biosynthesis, is central and often rate-limiting to regulate ethylene concentration in plants. The post-translational regulation of ACS is a major pathway controlling ethylene biosynthesis in response to various stimuli. We conclude that the regulation of ACS turnover may serve as a central hub for the rapid integration of developmental, environmental, and hormonal signals, all of which influence plant growth and stress responses. •Homodimerization and heterodimerization of ACS regulate not only ACS activity but also the stability of ACS proteins.•ACS turnover is controlled by a complex regulation of type-specific phosphorylation, dephosphorylation, and ubiquitination.•ACS turnover regulation influences various developmental processes.•The MPK signaling pathway appears to play a central role in ACS turnover-mediated stress responses.•Most phytohormones control ACS turnover with a distinct effect on different ACS isoforms.