Secdin is a small-molecule inhibitor of Arabidopsis thaliana ADP-ribosylation factor (ARF)-guanine nucleotide exchange factors (GEFs), impaires both hypocotyl and root growth in young Arabidopsis seedlings with IC50 of 4 uM.
Secdin (50 µM) did not affect seed germination.
Secdin application causes aberrant retention of plasma membrane (PM) proteins in late endosomal compartments, enhances vacuolar degradation, impaires protein recycling, and delays secretion and endocytosis.
Combined treatments with Secdin and the known ARF-GEF inhibitor Brefeldin A (BFA) prevents the BFA-induced PM stabilization of the ARF-GEF GNOM, impaires its translocation from the Golgi to the trans-Golgi network/early endosomes, and lead to the formation of hybrid endomembrane compartments reminiscent of those in ARF-GEF-deficient mutants.
Secdin impaires the intracellular transport of PM-localized proteins without directly affecting general aspects of the plant cell homeostasis.