Search

Fusarium subglutinans and F. temperatum are common maize pathogens that produce mycotoxins and cause plant disease. The ability of these species to produce beauvericin and fumonisin mycotoxins is not settled, as reports of toxin production are not concordant. Our objective was to clarify this situation by determining both chemotypes and genotypes for strains from both species. We analyzed 25 strains from Argentina - 13 of F. subglutinans and 12 of F. temperatum - for toxin production by UPLC-MS. We used new genome sequences from two strains of F. subglutinans and one strain of F. temperatum, plus genomes of other Fusarium species, to determine the presence of functional gene clusters for the synthesis of these toxins. None of the strains examined from either species produced fumonisins. These strains also lack Fum biosynthetic genes, but retain homologs of some genes that flank the Fum cluster in F. verticillioides. None of the F. subglutinans strains we examined produced beauvericin, although nine of 12 F. temperatum strains did. A complete beauvericin (Bea) gene cluster was present in all three new genome sequences. The Bea1 gene was presumably functional in F. temperatum, but was not functional in F. subglutinans due to a large insertion and multiple mutations that resulted in premature stop codons. The accumulation of only a few mutations expected to disrupt Bea1 suggests that the process of its inactivation is relatively recent. Thus, none of the strains of F. subglutinans or F. temperatum we examined produce fumonisins and the strains of F. subglutinans examined cannot produce beauvericin either. Variation in the ability of strains of F. temperatum to produce beauvericin requires further study and could reflect the recent shared ancestry of these two species. [ABSTRACT FROM AUTHOR]