EvSec22, a SNARE Protein, Regulates Hyphal Growth, Stress Tolerance, and Nematicidal Pathogenicity in Esteya vermicola

TL;DR

This study shows that the SNARE protein EvSec22 is crucial for the fungus Esteya vermicola to control the pinewood nematode and tolerate stress.

Contribution

The study identifies EvSec22 as a key SNARE protein involved in fungal pathogenicity and stress tolerance in E. vermicola.

Findings

EvSec22 deletion reduces E. vermicola's pathogenicity against B. xylophilus.

The mutant shows impaired hyphal growth, conidiation, and stress tolerance.

EvSec22 is linked to virulence and abiotic stress responses in E. vermicola.

Abstract

Bursaphelenchus xylophilus, the causative agent of pine wilt disease (PWD), poses a severe global threat to coniferous forests. Esteya vermicola, an endoparasitic nematophagous fungus, exhibits promising biocontrol potential against this pinewood nematode. The vesicular transport system, evolutionarily conserved in eukaryotes, is essential for fungal pathogenicity. Based on our genome sequence of E. vermicola CBS115803, we identified EvSec22, a gene encoding a SNARE protein implicated in vesicular transport process. This study investigates the role of EvSec22 in E. vermicola during nematode infection, utilizing our optimized gene knockout methodology. Infection assays revealed that EvSec22 deletion significantly impaired the pathogenicity of E. vermicola against B. xylophilus. Phenotypic analyses revealed that the ΔEvSec22 mutant exhibited suppressed hyphal growth, reduced conidiation, and abnormal septal spacing. Furthermore, the mutant showed significantly diminished tolerance to osmotic stress (sorbitol) and oxidative stress (hydrogen peroxide). Overall, the EvSec22 gene is associated with the virulence of E. vermicola CBS115803 against B. xylophilus, and its deletion also affects the normal growth of E. vermicola and its tolerance to abiotic stress. This study providing new insights into SNARE protein functions in fungal biocontrol agents.

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