Gibberellin DELLA signaling targets the retromer complex to redirect protein trafficking to the plasma membrane (PNAS)

Gibberellins including gibberellic acid (GA) are plant hormones required for growth and development. GA has been reported to regulate tropic responses by modulating plasma membrane localization of PIN auxin transporters. In this study, Salanenka et al. focused on the mechanism of GA-mediated protein trafficking to the plasma membrane. They showed that low levels of GA promote delivery of PIN proteins to the vacuole for degradation. In contrast, high levels of GA promote the recycling of PIN proteins to the plasma membrane. This GA-mediated effect requires SNX1 (Sorting Nexin 1) and CLASP1 (Cytoplasmic Linker-Associated Protein 1). This study provides evidence that DELLA proteins function non-transcriptionally by regulating microtubule and retromer complexes through their interacting partners Prefoldins (PFDs), and that GA has the capacity to redirect auxin transporters to the plasma membrane and regulate PIN-dependent auxin fluxes. (Summary by Arif Ashraf) PNAS: 10.1073/pnas.1721760115