Incidence And Molecular Characterization Of Fusarium Wilt In Tomato Production Systems

Abstract

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (Fol), is one of the most destructive diseases affecting tomato (Solanum lycopersicum L.) production worldwide. The present study was conducted to assess the incidence of Fusarium wilt in tomato production systems and to characterize the causal pathogen using morphological, pathogenicity, and molecular approaches. Field surveys carried out in major tomato-growing areas revealed the widespread occurrence of the disease, with incidence ranging from 12.4% to 48.7% across surveyed locations. Infected plants exhibited typical symptoms including chlorosis of lower leaves, unilateral wilting, vascular browning, stunted growth, and eventual plant death. Fungal isolates obtained from diseased tissues produced white to pink cottony colonies and characteristic microconidia, macroconidia, and chlamydospores consistent with Fusarium oxysporum. Pathogenicity assays confirmed the virulence of the isolates, as inoculated tomato seedlings developed typical wilt symptoms, whereas control plants remained symptom-free. Molecular characterization was performed through PCR amplification of the internal transcribed spacer (ITS) region and translation elongation factor-1 alpha (TEF-1α) gene, yielding fragments of approximately 550 bp and 700 bp, respectively. Sequence analysis revealed 99–100% similarity with authenticated F. oxysporum f. sp. lycopersici isolates available in GenBank. Furthermore, phylogenetic analyses based on ITS and TEF-1α sequences clustered all isolates within the Fol lineage with strong bootstrap support (>95%), confirming their taxonomic identity. The study demonstrates that Fusarium wilt remains a major constraint to sustainable tomato production and highlights the importance of integrating molecular diagnostics with conventional identification methods for accurate pathogen detection. Adoption of integrated disease management strategies, including resistant cultivars, crop rotation, biological control, and improved sanitation practices, is essential for reducing disease incidence and minimizing yield losses in tomato production systems.