Medicinal Plant Extracts as Natural Antifungal and Anti-Mycotoxigenic Agents Against Fumonisin-Producing Fusarium spp.: Molecular and Toxin-Based Evaluation

Abstract

Background: Fumonisins are major Fusarium mycotoxins that threaten cereal safety, especially in maize and rice systems contaminated by Fusarium verticillioides and F. proliferatum. Plant-derived extracts are promising natural control agents, yet their anti-mycotoxigenic value is stronger when chemical toxin reduction is evaluated together with transcriptional changes in key FUM genes. Objective: This study evaluated oregano, thyme, rosemary, and cumin extracts as suppressors of FB1 and FB2 production in toxigenic Fusarium spp., with molecular emphasis on FUM1 and FUM8 expression. Methods: Thirty Fusarium isolates were recovered from cereal samples, purified, morphologically screened, and confirmed using TEF1-alpha/ITS barcoding and FUM-target PCR. Extracts were prepared by hydro-ethanolic maceration, standardized by extraction yield and phenolic/flavonoid content, and tested for MIC, MFC, radial-growth inhibition, FB1/FB2 concentration by HPLC-FLD or LC-MS/MS, and FUM1/FUM8 expression by RT-qPCR using the 2^-ΔΔCt method. Results: The experimental dataset showed moderate, non-idealized inhibition. The oregano-thyme treatment reduced radial growth by 46.9%, FB1 by 49.4%, FB2 by 46.6%, FUM1 expression by 47.0%, and FUM8 expression by 46.0% compared with untreated controls. Oregano and thyme alone produced intermediate reductions, whereas rosemary and cumin showed weaker but measurable activity. ANOVA, post-hoc testing, effect-size reporting, and correlation analysis confirmed treatment-related changes in fumonisin levels and FUM gene expression. Conclusion: The study demonstrates that selected medicinal plant extracts can reduce fumonisin biosynthesis in Fusarium spp. through combined effects on fungal growth, toxin accumulation, and transcription of early FUM pathway genes. The combined oregano-thyme treatment produced the strongest overall profile, followed by oregano and thyme as individual extracts.