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Differing structures of galactoglucomannan in eudicots and non-eudicot angiosperms.

Published version
Peer-reviewed

Repository DOI


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Authors

Ishida, Konan 
Ohba, Yusuke 
Echevarría-Poza, Alberto 

Abstract

The structures of cell wall mannan hemicelluloses have changed during plant evolution. Recently, a new structure called β-galactoglucomannan (β-GGM) was discovered in eudicot plants. This galactoglucomannan has β-(1,2)-Gal-α-(1,6)-Gal disaccharide branches on some mannosyl residues of the strictly alternating Glc-Man backbone. Studies in Arabidopsis revealed β-GGM is related in structure, biosynthesis and function to xyloglucan. However, when and how plants acquired β-GGM remains elusive. Here, we studied mannan structures in many sister groups of eudicots. All glucomannan structures were distinct from β-GGM. In addition, we searched for candidate mannan β-galactosyltransferases (MBGT) in non-eudicot angiosperms. Candidate AtMBGT1 orthologues from rice (OsGT47A-VII) and Amborella (AtrGT47A-VII) did not show MBGT activity in vivo. However, the AtMBGT1 orthologue from rice showed MUR3-like xyloglucan galactosyltransferase activity in complementation analysis using Arabidopsis. Further, reverse genetic analysis revealed that the enzyme (OsGT47A-VII) contributes to proper root growth in rice. Together, gene duplication and diversification of GT47A-VII in eudicot evolution may have been involved in the acquisition of mannan β-galactosyltransferase activity. Our results indicate that β-GGM is likely to be a eudicot-specific mannan.

Description

Acknowledgements: We would like to thank the University of Cambridge Botanic Garden for providing monocots and ANA-grade samples. We also thank Ryo Yoshida for drawing beautiful plant illustrations and waiving their copyright.

Keywords

Humans, Mannans, Arabidopsis, Magnoliopsida, Galactosyltransferases, Plants, Phylogeny

Journal Title

PLoS One

Conference Name

Journal ISSN

1932-6203
1932-6203

Volume Title

18

Publisher

Public Library of Science (PLoS)
Sponsorship
UK Research and Innovation (EP/X027120/1)
EPSRC (1796471)
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