Isolation and Characterization of Potential Pathogenic Fungi Associated with Watermelons in Southwest Mississippi

Abstract

Watermelon is an important specialty crop in the USA. Fungal diseases primarily challenge the production and productivity of watermelon. The understanding of prevailing diseases, gained through genotypic and phenotypic techniques, eventually helps researchers develop disease management strategies. This study involved scouting and sampling of a watermelon research field in Southwest Mississippi for diseases. Nine distinct potential pathogenic fungi were identified from symptomatic leaves and fruits through development of pathogen pure cultures followed by PCR amplification of internal transcribed spacer regions and sequencing. The identified fungi were Didymella americana, Diaporthe melonis, Fusarium incarnatum, Alternaria longissima, Curvularia pseudobrachyspora, Xylaria multiplex, Phoma sp., Nigrospora sphaerica, and Fusarium chlamydosporum. The fungal isolates were ascomycetes at the phylum-level and belonged to the orders of fungi: Pleosporales, Hypocreales, Diaporthales, Xylariales, and Trichosphaeriales. Future research studies include pathogenicity assays with a broader host range, whole genome sequencing to develop deeper understanding of the pathogenic fungi, and formulation of disease management strategies for high-yielding, superior quality, and profitable watermelon production.