Pathogenicity, Virulence Factors, and Biofilm Formation of Pectobacterium carotovorum Causing Soft Rot in Potato

Abstract

Pathogenicity, virulence factors, and biofilm formation of Pectobacterium carotovorum causing soft rot in potato were investigated to elucidate mechanisms underlying tissue maceration and disease progression. Field-infected potato tubers exhibiting characteristic soft, water-soaked decay and foul odor were collected for bacterial isolation. Pure cultures were obtained and identified based on biochemical profiling and molecular confirmation using PCR amplification of species-specific genes. Pathogenicity assays on healthy potato tubers demonstrated significant variation in virulence among isolates, with highly aggressive strains causing rapid tissue maceration and extensive rotting within short incubation periods. Analysis of virulence determinants revealed the involvement of plant cell wall-degrading enzymes, including pectinases, cellulases, and proteases, which contributed to host tissue breakdown. Biofilm formation assays indicated strong adherence ability of virulent strains, enhancing survival, colonization, and persistence under environmental stress conditions. Isolates with higher biofilm-forming capacity exhibited increased pathogenicity, suggesting a direct relationship between biofilm development and disease severity. Molecular variability among isolates further indicated genetic diversity associated with differential virulence expression. Environmental factors such as temperature and humidity were found to influence disease development and bacterial proliferation. The study highlights the multifactorial nature of soft rot disease, driven by enzymatic activity, biofilm formation, and bacterial adaptability. These findings provide important insights for developing integrated disease management strategies, including improved post-harvest handling, resistant cultivars, and targeted control measures to reduce losses caused by P. carotovorum in potato production systems.