Lipid Droplet Inhibitors as Novel Fungicides Targeting Perylenequinone Toxin Production in Plant Pathogens

Overview

Plant pathogenic fungi cause significant crop losses worldwide, partly through the production of light-activated perylenequinone toxins such as cercosporin. These toxins generate reactive oxygen species (ROS) that damage plant cells and release nutrients the fungi feed on. A central mystery is how toxin-producing fungi avoid destroying themselves with their own toxins. This research proposes that fungi sequester these dangerous toxins inside lipid droplets (LDs), specialized cellular storage compartments, to keep them away from sensitive cellular machinery. If validated, disrupting LD formation or stability could reduce toxin production and provide a completely new mode of action for agricultural fungicides, addressing a critical need for novel crop protection chemistries.

Technical specifications

Core scientific findings:

• Light-activated perylenequinone toxins (e.g., cercosporin) produce ROS that damage plant cells but must be sequestered to protect the fungus itself
• Confocal microscopy of Cercospora cf. flagellaris revealed active cercosporin localized in vesicle-like structures, unlike inactive (reduced) cercosporin which was distributed uniformly in the cytoplasm
• High cercosporin-producing isolates showed numerically higher total lipid content compared to low-producing isolates

Planned validation activities:

• Use of LD-specific fluorescent dyes to confirm co-localization of cercosporin within lipid droplets via confocal microscopy
• Expanded testing across additional Cercospora species and isolates with quantitative LD measurement methods
• Pharmacological inhibition of LDs using cerulenin (a fatty acid synthase inhibitor) to measure effects on both LD abundance and cercosporin production
• Screening for additional fungal LD inhibitors with potential agricultural applications

Technology readiness level

This research is at an early discovery stage (TRL 2–3). The hypothesis is supported by preliminary microscopy evidence in one Cercospora species, with active toxin observed sequestered in vesicle-like structures. Key validation steps remain, including definitive co-localization studies, broader species testing, and pharmacological proof-of-concept experiments demonstrating that LD inhibition reduces toxin production. The research team seeks a one-year partnership to identify complementary LD inhibitors and support personnel and supplies, representing an opportunity for collaborators to engage at the foundational stage of a potentially novel fungicide development pathway.