Cysteine-rich peptide biofungicides for crop protection

Overview

This research program develops spray-on biofungicides based on small cysteine-rich cationic peptides derived from plant defensins. The core innovation involves sequence-modified peptide variants that demonstrate potent broad-spectrum antifungal activity at low micromolar concentrations against several fungal and oomycete crop pathogens. These variants are stable, cost-effective to produce, and exhibit both preventative and curative activity when applied to plants.

The lead candidate, PD30.6, is a 17-amino acid variant that inhibits the growth of five crop pathogens, including Botrytis cinerea, at submicromolar to low micromolar concentrations. A second peptide, PD50.1 (15 amino acids), also shows strong antifungal potential. Preliminary in planta testing in tomato against B. cinerea has produced promising preventative and curative results. The technology represents a novel biological alternative to conventional small-molecule fungicides, addressing growing concerns about resistance and regulatory restrictions.

Technical specifications

Key features:

• Small cationic peptides (15–17 amino acids) derived from plant defensins
• Sequence-optimized variants with enhanced antifungal potency compared to wild-type peptides
• Broad-spectrum activity against multiple fungal and oomycete crop pathogens
• Dual mechanism of action: fungal plasma membrane permeabilization and disruption of intracellular targets
• Cell wall binding and internalization by fungal cells
• Demonstrated preventative and curative in planta antifungal activity in tomato
• Stable molecular structure enabling cost-effective production
• Compatible with spray-on application methods

Research approach:

• Systematic sequential modification of wild-type peptides to identify efficacy-enhancing changes
• High-resolution live cell imaging using confocal and super-resolution microscopy to characterize mechanisms of internalization, subcellular dynamics, and peptide mobility
• Organelle-specific fluorescent labeling to identify multiple cellular targets in B. cinerea
• Comprehensive in vitro and in planta antifungal activity profiling across peptide variants

Technology readiness level

The technology is at an early-to-mid stage of development. The lead peptide PD30.6 has been characterized for antifungal activity in vitro and has shown promising preventative and curative results in preliminary tomato plant trials against B. cinerea. Collaborative validation with a major agricultural company has confirmed broad-spectrum activity against five crop pathogens. Future work will further elucidate structure-function relationships, mechanism of action, and expand in planta validation across additional peptide variants and crop-pathogen systems before advancing toward commercial development.