title: RAB5 activation is required for multiple steps in Arabidopsis thaliana root development.
abstract: Rab GTPases regulate the tethering and fusion of transport vesicles to target membranes in membrane trafficking by acting as a molecular switch, cycling between GDP- and GTP-bound states. RAB5 is a member of the Rab GTPase family, the members of which have been shown to perform various functions in the endocytic pathway, including the regulation of endosomal fusion and motility in animal cells. RAB5-mediated endosomal trafficking has also been found to play important roles in various higher order plant functions, which include the regulation of the polar transport of auxin and responses to environmental conditions. The regulatory mechanisms and functions of plant RAB5 have also been investigated at the molecular and cellular levels. However, the significance of RAB5 activity at the tissue and organ levels has hardly been investigated thus far. In the present study, we examined the effect of a mutation in VPS9a, which encodes the sole guanine nucleotide exchange factor for all RAB5s in the vegetative stages of Arabidopsis thaliana. We found that multiple developmental processes were impaired in the mutant plants, including the growth and pattern formation of the roots and establishment of auxin maxima. Our results indicate that RAB5 plays distinctive pivotal roles in the development of plants.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Inoue
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kondo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naramoto
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000235:genetics; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D020662:Guanine Nucleotide Exchange Factors; D008164:Luminescent Proteins; C556142:Vps9a protein, Arabidopsis; D020696:rab5 GTP-Binding Proteins
keywords: Arabidosis thaliana; Development; Endosomal traffic; Guanine nucleotide exchange factor; RAB5