Integrated polyphasic characterization and mycotoxin production of fungal isolates in sugarcane (Saccharum officinarum) stems from Thailand

Sugarcane ( Saccharum officinarum ) is a major agro-industrial crop in Thailand, whose sucrose-rich stems provide a favorable ecological niche for colonization by diverse fungal taxa, including species capable of producing harmful mycotoxins. Despite its importance, integrated assessments of fungal diversity and toxigenic potential in Thai sugarcane tissues remain limited. In this study, we applied an integrated polyphasic approach combining morphological characterization, multilocus phylogenetic analyses, and targeted liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) to characterize fungi isolated from sugarcane stems collected in Kanchanaburi Province, Thailand. A total of 64 isolates were assigned to nine genera, with Curvularia (57.81%), Fusarium (15.62%), and Nigrospora (9.38%) predominating. Multilocus sequence analyses based on the internal transcribed spacer region (ITS), translation elongation factor 1-alpha (TEF1- α ), RNA polymerase II second largest subunit (RPB2), β -tubulin (TUB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and calmodulin (CAM) resolved representative isolates into Curvularia plantarum , C. cf. guangxiensis , C. cf. clavata , Fusarium sacchari , F. pernambucanum , F. chlamydosporum , and Nigrospora zimmermanii . LC–ESI–MS/MS analysis revealed that all F. sacchari isolates were capable of producing beauvericin, whereas Paecilomyces lecythidis synthesized citrinin. Notably, this study provides, to the best of our knowledge, the first evidence of citrinin biosynthesis by P. lecythidis and represents the first integrated polyphasic evaluation of fungal diversity and mycotoxin-producing potential in Thai sugarcane stems. These findings highlight the presence of field-associated toxigenic fungi and suggest potential risks to food and feed safety, underscoring the need for surveillance strategies across the sugarcane production and processing chain.