The transcription factor SiROCX coordinates a stage-specific xylan- and cellulose-degrading secretome during immune-compatible colonization of monocot roots by Serendipita indica.

Authors

Laura Armbruster, Mathias Brands, Leo Baumgart, Frederic Dreesmann, Lisa Leson, Natalie Peltz, Vicente Ramírez, Yu Zhang, Taim Nassr, Gregor Langen, Markus Pauly, Alga Zuccaro

Published in

Plant communications. Pages 102181. Nov 05, 2026. Epub Nov 05, 2026.

Abstract

Intracellular accommodation of beneficial fungi requires controlled remodelling of host cell walls while avoiding excessive activation of plant immune responses. During colonization of monocot roots, the endophytic fungus Serendipita indica induces a suite of carbohydrate-active enzymes (CAZymes) targeting xylan and cellulose, but how this program is transcriptionally controlled in basidiomycetes is unknown. Here, we combined co-expression network analysis of time-resolved colonization transcriptomes with DNA affinity purification sequencing (DAP-seq) of module-associated transcription factors. This identified SiROCX, a Zn₂Cys₆ transcription factor of an Agaricomycetes-specific Roc1/ROCX lineage, whose DAP-seq-defined regulon is enriched in CAZyme genes. Inducible overexpression of SiROCX activated representative targets, enriched the secretome in CAZymes and enhanced xylanase and cellulase activities on xylan and delignified alcohol-insoluble residue (dAIR) of barley roots under in vitro conditions. Premature activation of this program during barley colonization was associated with early induction of a host immune marker despite comparable fungal biomass, consistent with a role for temporal control in maintaining symbiotic compatibility. Together, these findings identify SiROCX as a major regulator of a host-adapted cell wall-degrading secretome and reveal an Agaricomycetes-specific regulatory module that coordinates host cell wall remodelling with immune-compatible symbiotic colonization.

PMID:
42989722
Bibliographic data and abstract were imported from PubMed on 06 Nov 2026.

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