title: Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour in Populus.
abstract: Cortical microtubules are integral to plant morphogenesis, cell wall synthesis, and stomatal behaviour, presumably by governing cellulose microfibril orientation. Genetic manipulation of tubulins often leads to abnormal plant development, making it difficult to probe additional roles of cortical microtubules in cell wall biogenesis. Here, it is shown that expressing post-translational C-terminal modification mimics of α-tubulin altered cell wall characteristics and guard cell dynamics in transgenic Populus tremula x alba that otherwise appear normal. 35S promoter-driven transgene expression was high in leaves but unusually low in xylem, suggesting high levels of tubulin transgene expression were not tolerated in wood-forming tissues during regeneration of transformants. Cellulose, hemicellulose, and lignin contents were unaffected in transgenic wood, but expression of cell wall-modifying enzymes, and extractability of lignin-bound pectin and xylan polysaccharides were increased in developing xylem. The results suggest that pectin and xylan polysaccharides deposited early during cell wall biogenesis are more sensitive to subtle tubulin perturbation than cellulose and matrix polysaccharides deposited later. Tubulin perturbation also affected guard cell behaviour, delaying drought-induced stomatal closure as well as light-induced stomatal opening in leaves. Pectins have been shown to confer cell wall flexibility critical for reversible stomatal movement, and results presented here are consistent with microtubule involvement in this process. Taken together, the data show the value of growth-compatible tubulin perturbations for discerning microtubule functions, and add to the growing body of evidence for microtubule involvement in non-cellulosic polysaccharide assembly during cell wall biogenesis.
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA.
authors.forename: Prashant S
authors.initials: PS
authors.lastname: Swamy
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Hu
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Pattathil
authors.affiliation: Department of Wood Science, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Maloney
authors.affiliation: Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiao
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Liang-Jiao
authors.initials: LJ
authors.lastname: Xue
authors.affiliation: Division of Silviculture, Taiwan Forestry Research Institute, Taipei 10066, Taiwan.
authors.forename: Jeng-Der
authors.initials: JD
authors.lastname: Chung
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Virgil E
authors.initials: VE
authors.lastname: Johnson
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Gary F
authors.initials: GF
authors.lastname: Peter
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hahn
authors.affiliation: Department of Wood Science, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Mansfield
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Harding
authors.affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA cjtsai@uga.edu.
authors.forename: Chung-Jui
authors.initials: CJ
authors.lastname: Tsai
mesh_terms: D002473:Cell Wall / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology; D032107:Populus / Q000235:genetics / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014404:Tubulin
keywords: Cell wall; detyrosination; guard cell; microtubule; polysaccharide; tubulin post translational modification.