A loop-mediated isothermal amplification (LAMP) assay for rapid detection of fumonisin producing Aspergillus species

Fumonisins contamination of food commodities is a worldwide problem, especially for maize. The ability to produce fumonisins is a trait of several species of Fusarium, mainly F. verticillioides and F. proliferatum on maize, and some Aspergillus species. A. niger and its sister species A. welwitschiae, can contribute to fumonisin B2 (FB2) accumulation in maize kernels, although to a lesser extent than fumonisin-producing Fusarium species. Fumonisins risk monitoring represents an effective strategy in the integrated approach for mycotoxin risk management and reduction. The availability of a user-friendly molecular assay for the detection of toxigenic fungal species represents a valuable tool in understanding and managing upcoming mycotoxin contamination. In this study, we developed a LAMP assay, based on the detection of fum10, for a rapid and specific molecular detection of FB2-producing A. niger and A. welwistchiae, potentially useful to perform monitoring directly "on site" in maize chain. Results showed that very low amounts of conidia are suitable to detect the presence of the target gene, thus providing information about the presence of FB2-producing Aspergillus species and the possible upcoming fumonisins contamination in maize. The assay was combined with a suitable protocol for "in field" crude DNA extraction and a colorimetric method for easy naked-eye evaluation of results, offering a reliable and user-friendly tool to support effective reduction strategies of mycotoxin contamination in crop management programs.