Regulation of membrane trafficking and organ separation by the NEVERSHED ARF-GAP protein.
Cell separation, or abscission, is a highly specialized process in plants that facilitates remodeling of their architecture and reproductive success. Because few genes are known to be essential for organ abscission, we conducted a screen for mutations that alter floral organ shedding in Arabidopsis. Nine recessive mutations that block shedding were found to disrupt the function of an ADP-ribosylation factor-GTPase-activating protein (ARF-GAP) we have named NEVERSHED (NEV). As predicted by its homology to the yeast Age2 ARF-GAP and transcriptional profile, NEV influences other aspects of plant development, including fruit growth. Co-localization experiments carried out with NEV-specific antiserum and a set of plant endomembrane markers revealed that NEV localizes to the trans-Golgi network and endosomes in Arabidopsis root epidermal cells. Interestingly, transmission electron micrographs of abscission zone regions from wild-type and nev flowers reveal defects in the structure of the Golgi apparatus and extensive accumulation of vesicles adjacent to the cell walls. Our results suggest that NEV ARF-GAP activity at the trans-Golgi network and distinct endosomal compartments is required for the proper trafficking of cargo molecules required for cell separation.
Department of Biology and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA. liljegren@unc.edu
Sarah J
SJ
Liljegren
Michelle E
ME
Leslie
Lalitree
L
Darnielle
Michael W
MW
Lewis
Sarah M
SM
Taylor
Ruibai
R
Luo
Niko
N
Geldner
Joanne
J
Chory
Paul A
PA
Randazzo
Martin F
MF
Yanofsky
Joseph R
JR
Ecker
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000502:physiology* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001692:Biological Transport; D011992:Endosomes / Q000502:physiology*; D035264:Flowers / Q000502:physiology* / Q000648:ultrastructure; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000502:physiology*; D006056:Golgi Apparatus / Q000502:physiology* / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation
D029681:Arabidopsis Proteins; D020690:GTPase-Activating Proteins; C544765:NEV protein, Arabidopsis