PCR-based strategy to detect contamination with mycotoxigenic Fusarium species in maize.

Contamination of cereals with mycotoxigenic species of Fusarium is an important source of trichothecenes, fumonisins and other mycotoxins which cause serious diseases in human and animals. In addition, these species are phytopathogenic and produce severe losses in cereal yield. Methods for early detection of these Fusarium species are crucial to prevent toxins entering the food chain and are a useful tool in disease management practices. We have developed an integrated protocol for diagnosis of mycotoxigenic Fusarium contamination in maize which can also be used for other cereals. The protocol consisted in an easy and rapid DNA extraction from maize samples (grain and germ), and subsequent group-specific polymerase chain reaction (PCR) assays for genus Fusarium, Gibberella fujikuroi complex, and trichothecene-producing species of Fusarium, that orientate the search of the critical species. We have additionally developed a PCR assay for the identification of F. proliferatum. The primers were designed on the basis of IGS sequence (Intergenic Spacer of rDNA), a multi-copy region in the genome that permits to enhance the sensitivity of the assay in comparison with PCR assays based on single-copy sequences. The suitability of the protocol and the relative efficacy of single and multi-copy sequence-based PCR assays have been tested in a wide range of fumonisin-contaminated maize samples.