Ethylene regulates differential growth via BIG ARF-GEF-dependent post-Golgi secretory trafficking in Arabidopsis

Regulated movement to and from the plasma membrane (PM) has emerged as an important strategy for controlling the activity of plasma membrane proteins such as transporters and receptors. Jonsson et al. investigated the cellular machinery required for the insertion of the auxin-transport protein AUX1 into the plasma membrane from the trans-Golgi network. AUX1 is necessary for the ethylene-induced enhancement of the apical hook that protects the shoot as seedlings emerge from the soil. The authors address the contributions of ARFs and ARF-GEFs, proteins previously shown to be required for movement of vesicles from the trans-Golgi network. The authors found that different subtypes of ARF-GEFs (GNOMs and BIGs) act non-redundantly in apical hook formation. They also showed that BIGs and another protein, ECHIDNA (ECH) are both required for trafficking of AUX1 to the plasma membrane and maintenance of the apical hook. Plant Cell 10.​1105/​tpc.​16.​00743