# SNARE Protein CfSec22 Mediates Vesicular Trafficking to Regulate Growth, Conidiogenesis, and Pathogenesis of Ceratocystis fimbriata

## TL;DR

A SNARE protein called CfSec22 helps control growth, spore production, and infection in a plant-damaging fungus.

## Contribution

This study identifies CfSec22 as a key regulator of vesicle trafficking in the fungal pathogen Ceratocystis fimbriata.

## Key findings

- CfSec22 deletion causes abnormal vacuole morphology and endocytosis defects.
- CfSec22 is essential for virulence-associated protein secretion and ipomeamarone induction in infected plants.
- The protein localizes to the endoplasmic reticulum and is sensitive to multiple stress conditions.

## Abstract

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins play evolutionarily conserved roles in intracellular vesicle trafficking and membrane fusion across eukaryotes. In pathogenic fungi, various SNARE homologs have been shown to critically regulate host infection processes. Here, we characterize the functional roles of CfSec22 in the sweet potato black rot pathogen Ceratocystis fimbriata. Phylogenetic and domain analyses demonstrate that CfSec22 shares homology with Sec22 proteins from Saccharomyces cerevisiae (ScSec22), Magnaporthe oryzae (MoSec22), and other fungi, containing both the characteristic Longin homology domain and V-SNARE domain. Functional studies reveal that CfSec22 regulates growth, conidiation, and virulence of C. fimbriata. Deletion of CfSEC22 resulted in abnormal vacuole morphology and impaired endocytosis. The ΔCfsec22 mutant displayed heightened sensitivity to diverse stress conditions: oxidative, endoplasmic reticulum, and cell wall stressors. Subcellular localization studies confirmed the endoplasmic reticulum residence of CfSec22. Finally, we established that CfSec22 regulates the secretion of virulence-associated proteins and is required for the induction of ipomeamarone in infected sweet potato tissues. Together, our findings demonstrate that CfSec22-mediated vesicle trafficking serves as a critical regulatory mechanism supporting growth, conidiogenesis, and pathogenicity in C. fimbriata.