Novel insecticidal toxins from Culicinomyces clavisporus for next-generation pest control

Overview

This research program focuses on identifying and validating novel insecticidal toxins produced by the entomopathogenic fungus Culicinomyces clavisporus. Unlike most fungal insect pathogens that infect through the cuticle, this fungus initiates infection through ingestion, suggesting its genome encodes macromolecules specifically toxic when consumed by insect hosts. Transcriptome sequencing has revealed multiple candidate toxin genes, including a fully validated sequence predicted to encode a 162-amino-acid ribotoxin with homology to the known insecticidal protein Hirsutellin A. The goal is to translate these fungal toxins into plant-incorporated protectants (PIPs) that provide robust protection against major agricultural pests such as fall armyworm and diamondback moth.

Technical specifications

• Validated candidate toxin: A 162-amino-acid protein containing a signal peptide and a ribotoxin domain similar to Hirsutellin A, confirmed through PacBio transcriptome sequencing, RACE-PCR, and Sanger resequencing.
• Additional candidates: Multiple insecticidal toxin-related genes identified through homology searches, with open reading frames still being completed.
• Expression strategy: Candidate genes will be produced in protein expression systems as standalone toxins or in synergistic combinations, with Bt Cry toxins used as benchmarks and potential co-toxins.
• Bioinformatics pipeline: High-throughput PacBio reads (3,000,000+) analyzed to identify candidate genes, followed by ORF validation and domain prediction.
• Proteomics integration: Planned post-translational modification analysis to account for functional impacts on toxin activity.
• Target pests: Fall armyworm (Spodoptera frugiperda) and diamondback moth (Plutella xylostella), with extensibility to other lepidopteran pests.

Technology readiness level

The project is at an early-to-mid discovery stage (TRL 2–3). The fungal strain (ARSEF 582) has been cultured, and one candidate toxin gene has been fully validated at the sequence level. The next phase involves heterologous protein expression and bioassay validation against target pests. Additional candidate genes require completion of their open reading frames before expression testing. A longer-term objective includes completing the full fungal genome to identify the complete suite of insect-active macromolecules, followed by proteomics-based functional characterization.