title: Kinesin-4 Functions in Vesicular Transport on Cortical Microtubules and Regulates Cell Wall Mechanics during Cell Elongation in Plants.
abstract: In plants, anisotropic cell expansion depends on cortical microtubules that serve as tracks along which macromolecules and vesicles are transported by the motor kinesins of unknown identities. We used cotton (Gossypium hirsutum) fibers that underwent robust elongation to discover kinesins that are involved in cell elongation and found Gh KINESIN-4A expressed abundantly. The motor was detected by immunofluorescence on vesicle-like structures that were associated with cortical microtubules. In Arabidopsis thaliana, the orthologous motor At KINESIN-4A/FRA1, previously implicated in cellulose deposition during secondary growth in fiber cells, was examined by live-cell imaging in cells expressing the fluorescently tagged functional protein. The motor decorated vesicle-like particles that exhibit a linear movement along cortical microtubules with an average velocity of 0.89 μm/min, which was significantly different from those linked to cellulose biosynthesis. We also discovered that At KINESIN-4A/FRA1 and the related At KINESIN-4C play redundant roles in cell wall mechanics, cell elongation, and the axial growth of various vegetative and reproductive organs, as the loss of At KINESIN-4C greatly enhanced the defects caused by a null mutation at the KINESIN-4A/FRA1 locus. The double mutant displayed a lack of cell wall softening at normal stages of rapid cell elongation. Furthermore, enhanced deposition of arabinose-containing carbohydrate was detected in the kinesin-4 mutants. Our findings established a connection between the Kinesin-4-based transport of cargoes containing non-cellulosic components along cortical microtubules and cell wall mechanics and cell elongation in flowering plants.
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA; State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Zhaosheng
authors.initials: Z
authors.lastname: Kong
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA.
authors.forename: Motohide
authors.initials: M
authors.lastname: Ioki
authors.affiliation: Sainsbury Laboratory Cambridge, University of Cambridge, Cambridge CB2 1LR, UK.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Braybrook
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, PA 16802, USA.
authors.forename: Shundai
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Plant Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Zheng-Hua
authors.initials: ZH
authors.lastname: Ye
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA.
authors.forename: Yuh-Ru
authors.initials: YR
authors.lastname: Julie Lee
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hotta
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA.
authors.forename: Anny
authors.initials: A
authors.lastname: Chang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Guangda
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Plant Biology, University of California, Davis, CA 95616, USA. Electronic address: bliu@ucdavis.edu.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002473:Cell Wall / Q000378:metabolism*; D004548:Elasticity; D003368:Gossypium / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation; D021381:Protein Transport; D012639:Seeds / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D016547:Kinesins
keywords: Arabidopsis; cotton; cytoskeleton; cytoskeleton–cell wall interactions; leaf/vegetative development