title: Deficient sucrose synthase activity in developing wood does not specifically affect cellulose biosynthesis, but causes an overall decrease in cell wall polymers.
abstract: The biosynthesis of wood in aspen (Populus) depends on the metabolism of sucrose, which is the main transported form of carbon from source tissues. The largest fraction of the wood biomass is cellulose, which is synthesized from UDP-glucose. Sucrose synthase (SUS) has been proposed previously to interact directly with cellulose synthase complexes and specifically supply UDP-glucose for cellulose biosynthesis. To investigate the role of SUS in wood biosynthesis, we characterized transgenic lines of hybrid aspen with strongly reduced SUS activity in developing wood. No dramatic growth phenotypes in glasshouse-grown trees were observed, but chemical fingerprinting with pyrolysis-GC/MS, together with micromechanical analysis, showed notable changes in chemistry and ultrastructure of the wood in the transgenic lines. Wet chemical analysis showed that the dry weight percentage composition of wood polymers was not changed significantly. However, a decrease in wood density was observed and, consequently, the content of lignin, hemicellulose and cellulose was decreased per wood volume. The decrease in density was explained by a looser structure of fibre cell walls as shown by increased wall shrinkage on drying. The results show that SUS is not essential for cellulose biosynthesis, but plays a role in defining the total carbon incorporation to wood cell walls.
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Gerber
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, DE 144 24, Potsdam, Germany.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Melissa
authors.initials: M
authors.lastname: Roach
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Umut
authors.initials: U
authors.lastname: Rende
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: András
authors.initials: A
authors.lastname: Gorzsás
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, DE 144 24, Potsdam, Germany.|Institute for Building Materials, ETH Zurich, 8093, Zurich, Switzerland.|Empa - Swiss Federal Laboratories for Material Testing and Research, Applied Wood Materials Laboratory, 8600, Dübendorf, Switzerland.
authors.forename: Ingo
authors.initials: I
authors.lastname: Burgert
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Totte
authors.initials: T
authors.lastname: Niittylä
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
mesh_terms: D017360:Arabidopsis / Q000201:enzymology; D001696:Biomechanical Phenomena; D002473:Cell Wall / Q000378:metabolism*; D002482:Cellulose / Q000096:biosynthesis*; D003433:Crosses, Genetic; D018506:Gene Expression Regulation, Plant; D005964:Glucosyltransferases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D034622:RNA Interference; D012995:Solubility; D059467:Transcriptome / Q000235:genetics; D014934:Wood / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*
chemical_list: D002482:Cellulose; D005964:Glucosyltransferases; C022699:sucrose synthase
keywords: Populus; aspen; cell wall; cellulose; sucrose synthase (SUS); wood