title: TNO1, a TGN-localized SNARE-interacting protein, modulates root skewing in Arabidopsis thaliana.
abstract: The movement of plant roots within the soil is key to their ability to interact with the environment and maximize anchorage and nutrient acquisition. Directional growth of roots occurs by a combination of sensing external cues, hormonal signaling and cytoskeletal changes in the root cells. Roots growing on slanted, impenetrable growth medium display a characteristic waving and skewing, and mutants with deviations in these phenotypes assist in identifying genes required for root movement. Our study identifies a role for a trans-Golgi network-localized protein in root skewing.
  
  
  
  We found that Arabidopsis thaliana TNO1 (TGN-localized SYP41-interacting protein), a putative tethering factor localized at the trans-Golgi network, affects root skewing. tno1 knockout mutants display enhanced root skewing and epidermal cell file rotation. Skewing of tno1 roots increases upon microtubule stabilization, but is insensitive to microtubule destabilization. Microtubule destabilization leads to severe defects in cell morphology in tno1 seedlings. Microtubule array orientation is unaffected in the mutant roots, suggesting that the increase in cell file rotation is independent of the orientation of microtubule arrays.
  
  
  
  We conclude that TNO1 modulates root skewing in a mechanism that is dependent on microtubules but is not linked to disruption of the orientation of microtubule arrays. In addition, TNO1 is required for maintenance of cell morphology in mature regions of roots and the base of hypocotyls. The TGN-localized SNARE machinery might therefore be important for appropriate epidermal cell file rotation and cell expansion during root growth.
authors.affiliation: Department of Genetics, Development and Cell Biology, 1035B Roy J Carver Co-Lab, 1111 WOI Rd, Iowa State University, Ames, IA, 50011, USA.|Interdepartmental Genetics Program, Iowa State University, Ames, IA, USA.|Current Address: Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, MN 55108, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Roy
authors.affiliation: Department of Genetics, Development and Cell Biology, 1035B Roy J Carver Co-Lab, 1111 WOI Rd, Iowa State University, Ames, IA, 50011, USA. bassham@iastate.edu.|Interdepartmental Genetics Program, Iowa State University, Ames, IA, USA. bassham@iastate.edu.|Plant Sciences Institute, Iowa State University, Ames, IA, USA. bassham@iastate.edu.
authors.forename: Diane C
authors.initials: DC
authors.lastname: Bassham
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001549:Benzamides / Q000494:pharmacology; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D001549:Benzamides; D050600:SNARE Proteins; C561281:TGN-localized SYP41-interacting protein, Arabidopsis; D033921:Vesicular Transport Proteins; C001059:pronamide
keywords: Cell file rotation; Microtubules; Root movement; Tethering factor; trans-Golgi network