An Exo2 Derivative Affects ER and Golgi Morphology and Vacuolar Sorting in a Tissue‐Specific Manner in Arabidopsis

• Published in: Traffic (Copenhagen, Denmark) Denmark), 2011-11, Vol.12 (11), p.1552-1562
• Main Authors: Sorieul, Mathias, Langhans, Markus, Guetzoyan, Lucie, Hillmer, Stefan, Clarkson, Guy, Lord, John Michael, Roberts, Lynne M., Robinson, David G., Spooner, Robert A., Frigerio, Lorenzo
• Format: Article
• Language: English
• Subjects: ADP-Ribosylation Factors - metabolism; Arabidopsis - drug effects; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Benzaldehydes - pharmacology; brefeldin A; Brefeldin A - pharmacology; BRI1; Cell Membrane - drug effects; Cell Membrane - metabolism; chemical genomics; Dinitrobenzenes - pharmacology; endocytosis; endoplasmic reticulum; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum - ultrastructure; endosome; Endosomes - drug effects; Endosomes - metabolism; Exo2; Golgi; Golgi Apparatus - drug effects; Golgi Apparatus - metabolism; Golgi Apparatus - ultrastructure; Plant Roots - drug effects; Plant Roots - metabolism; plant secretory pathway; Protein Kinases - metabolism; Protein Transport; Pyridinium Compounds - metabolism; Pyrimidines - pharmacology; Quaternary Ammonium Compounds - metabolism; Secretory Pathway - drug effects; Sulfanilamides - pharmacology; trans-Golgi Network - drug effects; trans-Golgi Network - metabolism; vacuole; Vacuoles - drug effects; Vacuoles - metabolism
• ISSN: 1398-9219; 1600-0854
• DOI: 10.1111/j.1600-0854.2011.01258.x

We screened a panel of compounds derived from Exo2—a drug that perturbs post‐Golgi compartments and trafficking in mammalian cells—for their effect on the secretory pathway in Arabidopsis root epidermal cells. While Exo2 and most related compounds had no significant effect, one Exo2 derivative, named LG8, induced severe morphological alterations in both the Golgi (at high concentrations) and the endoplasmic reticulum (ER). LG8 causes the ER to form foci of interconnecting tubules, which at the ultrastructural level appear similar to those previously reported in Arabidopsis roots after treatment with the herbicide oryzalin. In cotyledonary leaves, LG8 causes redistribution of a trans Golgi network (TGN) marker to the vacuole. LG8 affects the anterograde secretory pathway by inducing secretion of vacuolar cargo and preventing the brassinosteroid receptor BRI1 from reaching the plasma membrane. Uptake and arrival at the TGN of the endocytic marker FM4‐64 is not affected. Unlike the ADP ribosylation factor‐GTP exchange factor (ARF‐GEF) inhibitor brefeldin A (BFA), LG8 affects these post‐Golgi events without causing the formation of BFA bodies. Up to concentrations of 50 µm, the effects of LG8 are reversible.