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.
Liljegren
Sarah J
SJ
Department of Biology and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA. liljegren@unc.edu
Leslie
Michelle E
ME
Darnielle
Lalitree
L
Lewis
Michael W
MW
Taylor
Sarah M
SM
Luo
Ruibai
R
Geldner
Niko
N
Chory
Joanne
J
Randazzo
Paul A
PA
Yanofsky
Martin F
MF
Ecker
Joseph R
JR
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