title: Suppression of xylan endotransglycosylase PtxtXyn10A affects cellulose microfibril angle in secondary wall in aspen wood.
abstract: Certain xylanases from family GH10 are highly expressed during secondary wall deposition, but their function is unknown. We carried out functional analyses of the secondary-wall specific PtxtXyn10A in hybrid aspen (Populus tremula × tremuloides). PtxtXyn10A function was analysed by expression studies, overexpression in Arabidopsis protoplasts and by downregulation in aspen. PtxtXyn10A overexpression in Arabidopsis protoplasts resulted in increased xylan endotransglycosylation rather than hydrolysis. In aspen, the enzyme was found to be proteolytically processed to a 68 kDa peptide and residing in cell walls. Its downregulation resulted in a corresponding decrease in xylan endotransglycosylase activity and no change in xylanase activity. This did not alter xylan molecular weight or its branching pattern but affected the cellulose-microfibril angle in wood fibres, increased primary growth (stem elongation, leaf formation and enlargement) and reduced the tendency to form tension wood. Transcriptomes of transgenic plants showed downregulation of tension wood related genes and changes in stress-responsive genes. The data indicate that PtxtXyn10A acts as a xylan endotransglycosylase and its main function is to release tensional stresses arising during secondary wall deposition. Furthermore, they suggest that regulation of stresses in secondary walls plays a vital role in plant development.
authors.affiliation: Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden.
authors.forename: Marta
authors.initials: M
authors.lastname: Derba-Maceluch
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Awano
authors.forename: Junko
authors.initials: J
authors.lastname: Takahashi
authors.forename: Jessica
authors.initials: J
authors.lastname: Lucenius
authors.forename: Christine
authors.initials: C
authors.lastname: Ratke
authors.forename: Inkeri
authors.initials: I
authors.lastname: Kontro
authors.forename: Marta
authors.initials: M
authors.lastname: Busse-Wicher
authors.forename: Ondrej
authors.initials: O
authors.lastname: Kosik
authors.forename: Ryo
authors.initials: R
authors.lastname: Tanaka
authors.forename: Anders
authors.initials: A
authors.lastname: Winzéll
authors.forename: Åsa
authors.initials: Å
authors.lastname: Kallas
authors.forename: Joanna
authors.initials: J
authors.lastname: Leśniewska
authors.forename: Fredrik
authors.initials: F
authors.lastname: Berthold
authors.forename: Peter
authors.initials: P
authors.lastname: Immerzeel
authors.forename: Tuula T
authors.initials: TT
authors.lastname: Teeri
authors.forename: Ines
authors.initials: I
authors.lastname: Ezcurra
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.forename: Ritva
authors.initials: R
authors.lastname: Serimaa
authors.forename: Ewa J
authors.initials: EJ
authors.lastname: Mellerowicz
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D002678:Chimera; D018506:Gene Expression Regulation, Plant; D006868:Hydrolysis; D020894:Microfibrils; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D014934:Wood / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology; D014990:Xylans / Q000378:metabolism; D052584:Xylem / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014990:Xylans; D002482:Cellulose; D014995:Xylosidases
keywords: Populus; endotransglycosylase; growth stresses; hybrid aspen; secondary cell wall; wood formation; xylan; xylanase