Antibiosis and transcriptomic analysis of inhibitory effect of the endophytic fungus Simplicillium lamellicola against phytopathogenic fungi

Abstract

Endophytic fungus such as Simplicillium lamellicola exhibit pronounced antagonistic activity against a broad spectrum of plant pathogens. However, the molecular mechanisms underlying their fungal-fungal interactions remain insufficiently understood. In this study, we investigated the antagonistic effects of S. lamellicola against two necrotrophic pathogens, Thielaviopsis paradoxa and Heterobasidion annosum, through dual-culture assays integrated with comparative transcriptomic analyses. S. lamellicola significantly inhibited by antibiosis the growth of both pathogens, inducing conspicuous morphological alterations including hyphal distortion, hyper-branching, and cellular lysis at the interaction interfaces. Transcriptomic profiling revealed extensive transcriptional reprogramming, identifying 1336 differentially expressed genes (DEGs) in T. paradoxa (TpSl) and 441 in H. annosum (HaSl), with a predominance of downregulated genes (66.2 % and 56.2 %, respectively). Functional annotation indicated shared stress-adaptive responses encompassing oxidative stress defense, detoxification processes, and nutrient competition, accompanied by distinct species-specific strategies: T. paradoxa exhibited enhanced membrane restructuring, efflux-mediated transport, and structural reinforcement, whereas H. annosum activated chemically mediated defense pathways and oxidative stress mitigation mechanisms. Collectively, these findings demonstrate that S. lamellicola functions as a potent mycoparasitic biocontrol agent capable of eliciting complex defense responses in phytopathogenic fungi, thereby providing a molecular framework for its application in sustainable plant disease management.Peer reviewe