Dual RNA-seq reveals transcriptome changes during Fusarium virguliforme-Trichoderma afroharzianum interactions

Area of Science:

• Mycology
• Plant Pathology
• Molecular Biology

Background:

• Trichoderma spp. are vital biocontrol agents, but their pathogen recognition mechanisms and intra-species variability require further study.
• Understanding these interactions is key to optimizing biological control programs.
• Phenotypic differences in Trichoderma afroharzianum (T. afroharzianum) isolates during pathogen confrontation are well-documented but poorly understood.

Purpose of the Study:

• To investigate the transcriptomic differences between two T. afroharzianum isolates (Th19A and Th4) when interacting with Fusarium virguliforme (F. virguliforme).
• To elucidate the molecular mechanisms underlying the observed phenotypic variations in biocontrol efficacy.
• To identify pathogen recognition pathways, including potential volatile-mediated signaling.

Main Methods:

• Dual plate assays were used to compare the antagonistic activity of T. afroharzianum isolates against F. virguliforme.
• RNA sequencing was performed to analyze the transcriptomes of both F. virguliforme and T. afroharzianum at different interaction stages.
• Gene Ontology (GO) enrichment analysis was employed to identify differentially expressed genes and pathways.

Main Results:

• Th19A overgrew F. virguliforme, while Th4 exhibited an inhibition zone, indicating distinct interaction outcomes.
• Significant transcriptomic differences were observed in F. virguliforme when interacting with Th19A versus Th4, and across different time points.
• Both F. virguliforme and T. afroharzianum exhibited significant transcriptome changes, with distinct GO-enriched categories between isolates and interaction stages.
• Upregulation of secreted proteins, including carbohydrate-active enzymes (CAZymes) and CBM1-domain proteins, was observed in both T. afroharzianum isolates even before physical contact, suggesting volatile-mediated recognition.

Conclusions:

• The study reveals significant transcriptomic plasticity in F. virguliforme and T. afroharzianum during their interaction.
• Differential gene expression, particularly of secreted proteins, suggests complex recognition mechanisms, including volatile signaling.
• These findings are crucial for developing more effective and targeted biocontrol strategies using specific Trichoderma isolates.