title: Over-expression of OsAGAP, an ARF-GAP, interferes with auxin influx, vesicle trafficking and root development.
abstract: Development and organogenesis in both dicot and monocot plants are highly dependent on polar auxin transport (PAT), which requires the proper asymmetric localization of both auxin influx and efflux carriers. In the model dicot plant Arabidopsis thaliana, the trafficking and localization of auxin efflux facilitators such as PIN-FORMED1 (PIN1) are mediated by GNOM, a guanine-nucleotide exchange factor (GEF) for the ADP-ribosylation factor (ARF) family of small GTPases, but molecular regulators of the auxin influx facilitators remain unknown. Here, we show that over-expression of OsAGAP, an ARF-GTPase-activating protein (ARF-GAP) in rice, impaired PAT and interfered with both primary and lateral root development. The lateral root phenotype could be rescued by the membrane-permeable auxin 1-naphthyl acetic acid, but not by indole 3-acetic acid (IAA) or by 2,4-dichloro-phenoxyacetic acid, which require influx facilitators to enter the cells. OsAGAP-over-expressing plants had alterations in vesicle trafficking and localization of the presumptive A. thaliana auxin-influx carrier AUX1, but not in the localization of the auxin efflux facilitators. Together, our data suggest that OsAGAP has a specific role in regulating vesicle trafficking pathways such as the auxin influx pathway, which in turn controls auxin-dependent root growth in plants.
authors.affiliation: Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Zhuang
authors.forename: Jiafu
authors.initials: J
authors.lastname: Jiang
authors.forename: Junhua
authors.initials: J
authors.lastname: Li
authors.forename: Qibin
authors.initials: Q
authors.lastname: Ma
authors.forename: Yunyuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Yongbiao
authors.initials: Y
authors.lastname: Xue
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Xu
authors.forename: Kang
authors.initials: K
authors.lastname: Chong
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified
chemical_list: D020690:GTPase-Activating Proteins; D007210:Indoleacetic Acids; D010940:Plant Proteins