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Research article - Peer-reviewed, 2022

Laccaria bicolor pectin methylesterases are involved in ectomycorrhiza development with Populus tremula x Populus tremuloides

Chowdhury, Jamil; Kemppainen, Minna; Delhomme, Nicolas; Shutava, Iryna; Zhou, Jingjing; Takahashi, Junko; Pardo, Alejandro G.; Lundberg-Felten, Judith;

Abstract

The development of ectomycorrhizal (ECM) symbioses between soil fungi and tree roots requires modification of root cell walls. The pectin-mediated adhesion between adjacent root cells loosens to accommodate fungal hyphae in the Hartig net, facilitating nutrient exchange between partners. We investigated the role of fungal pectin modifying enzymes in Laccaria bicolor for ECM formation with Populus tremula x Populus tremuloides. We combine transcriptomics of cell-wall-related enzymes in both partners during ECM formation, immunolocalisation of pectin (Homogalacturonan, HG) epitopes in different methylesterification states, pectin methylesterase (PME) activity assays and functional analyses of transgenic L. bicolor to uncover pectin modification mechanisms and the requirement of fungal pectin methylesterases (LbPMEs) for ECM formation. Immunolocalisation identified remodelling of pectin towards de-esterified HG during ECM formation, which was accompanied by increased LbPME1 expression and PME activity. Overexpression or RNAi of the ECM-induced LbPME1 in transgenic L. bicolor lines led to reduced ECM formation. Hartig Nets formed with LbPME1 RNAi lines were shallower, whereas those formed with LbPME1 overexpressors were deeper. This suggests that LbPME1 plays a role in ECM formation potentially through HG de-esterification, which initiates loosening of adjacent root cells to facilitate Hartig net formation.

Keywords

cell wall; cell-wall remodelling; cell-wall-modifying enzymes; ectomycorrhiza; Laccaria bicolor; pectin; pectin methylesterase; Populus

Published in

New Phytologist

2022, volume: 236, number: 2, pages: 639-655
Publisher: WILEY

Authors' information

Chowdhury, Jamil (Chowdhury, Jamil)
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Chowdhury, Jamil (Chowdhury, Jamil)
Umeå University
Kemppainen, Minna
Centro Nacional Patagonico (CENPAT)
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Shutava, Iryna
Umea University
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Umeå University
Pardo, Alejandro G.
Centro Nacional Patagonico (CENPAT)

UKÄ Subject classification

Forest Science

Publication Identifiers

DOI: https://doi.org/10.1111/nph.18358

URI (permanent link to this page)

https://res.slu.se/id/publ/118531