Regulation of ethylene biosynthesis

The biosynthesis of the gaseous phytohormone ethylene is a highly regulated process. A major point of regulation occurs at the generally rate-limiting step in biosynthesis, catalyzed by the enzyme ACC synthase (ACS). ACS is encoded by a multigene family, and different members show distinct patterns of expression during growth and development, and in response to various external cues. In addition to this transcriptional control, the stability of the ACS protein is also highly regulated. Here we review these two distinct regulatory inputs that control the spatial and temporal patterns of ethylene biosynthesis.