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 tremulaxtremuloides).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 68kDa 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.

Keywords

endotransglycosylase; growth stresses; hybrid aspen; Populus; secondary cell wall; wood formation; xylan; xylanase

Published in

New Phytologist
2015, volume: 205, number: 2, pages: 666-681
Publisher: WILEY-BLACKWELL

SLU Authors

• Derba-Maceluch, Marta

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Takahashi Schmidt, Junko

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Ratke, Christine

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Lesniewska, Joanna

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    
  • University of Białystok

• Immerzeel, Peter

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Mellerowicz, Ewa

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Botany

Publication identifier

• DOI: https://doi.org/10.1111/nph.13099

Permanent link to this page (URI)

https://res.slu.se/id/publ/77121