Infection mechanisms of Pochonia chlamydosporia: A breakthrough in Fasciola hepatica egg control

Traditional parasite management has long been plagued by issues such as drug resistance and environmental pollution. Biological control using Pochonia chlamydosporia has emerged as a sustainable alternative, yet the underlying infection mechanisms remain elusive. This study aimed to comprehensively elucidate these mechanisms, with a particular focus on the role of gene editing. Employing optical, SEM, and TEM microscopy, we observed that P. chlamydosporia infects Fasciola hepatica eggs in three distinct stages. TEM analysis first visualized unique infection pegs crucial for initial eggshell penetration. Using 4D-DIA mass spectrometry, proteomics identified 208 differentially expressed proteins between normal and nematode - egg - induced mycelium, of which 93 were downregulated and 115 were upregulated. Through comprehensive protein sequencing and subsequent bioinformatics analyses, we successfully identified a key gene, designated p1. To understand p1's function, we used RNA interference (RNAi) and overexpression. We constructed pSilent-1-p1 (RNAi vector) and pBARGPE1-p1 (overexpression vector). The overexpression strain pBARGPE-p1 demonstrated a remarkable increase in serine protease activity (0.63 U/mL), indicating an enhanced ability to degrade host tissues. Conversely, the deletion strain pSilent-1-p1 had lower activity, indicating the crucial role of the p1 gene in protease production. When assessing the infection efficiency against three types of nematode eggs, both the overexpressed and silenced strains exhibited a downward trend. The silenced strain had a significantly reduced infection rate, with an average of 45.22 %, highlighting the importance of the p1 gene in the fungus's parasitic ability. Notably, no significant differences were observed among strains with respect to spore concentration, mycelial biomass, and growth rate. These findings, centered on the p1 gene provide comprehensive insights into the biological control mechanisms of P. chlamydosporia, establishing a solid theoretical foundation for the development of more efficient and environmentally friendly parasite management strategies.