Differences in the Beauvericin Gene Cluster and toxin production in Fusarium subglutinans and Fusarium temperatum.

FUMERO, M.V.; VILLANI, A.; SUSCA, A.; HAIDUKOWSKI, M.; CIMMARUSTI, M.T.; LESLIE, J.F.; CHULZE, S.N.; TOOMAJIAN, C.; MORETTI, A.

Conferencia; 1er Conferencia Internacional de MycoKey.; 2017

MycoKey

8.48. Differences in the Beauvericin Gene Cluster and Toxin Production in Fusarium subglutinans andFusarium temperatumAbstract: Beauvericin (BEA) is a secondary metabolite produced by many species of Fusarium. F. circinatum, F. fujikuroi, F. mangiferae, F. nygamai, F. proliferatum, F. sacchari, F. oxysporum and F. temperatum are producers, while species such as F. verticillioides, F. thapsinum and F. subglutinans are non-producers. Wheat, rice, corn, barley and cereal products are the commodities most commonly contaminated with BEA. Beauvericin is a cyclic hexadepsipeptide that incorporates into biological membranes where it complexes with essential cations, increasing membrane permeability and altering cellular homeostasis. BEA is cytotoxic to some cell lines in vitro and potentially genotoxic to human lymphocytes, where it is associated with chromosomal aberrations. Genes encoding BEA biosynthesis were first described for F. fujikuroi. In this and other Fusarium species, including F. mangiferae, F. proliferatum and F. oxysporum, a cluster of four genes, including a non-ribosomal peptide synthase (NRPS22) and three accessory genes with transport and regulatory functions, are responsible for toxin biosynthesis. Fusarium subglutinans and F. temperatum are both maize pathogens that are closely related and indistinguishable based solelyon morphology. BEA production distinguishes these species, however, as F. temperatum can produce BEA but F. subglutinans cannot. We recovered 25 Fusarium strains from maize harvested in Argentina. Based on partial EF-1α, β-tubulin and RPB2 sequences, 13 strains were identified as F. subglutinans and 12 as F. temperatum. BEA production was evaluated after growth in YES medium for 14 days at 25°C. None of the 13 F. subglutinans strains produced BEA, while 9/12 of the F. temperatum strains produced BEA at between 7 and 400 µg/g. Genomic comparison of two species highlighted for the first time the presence in both species of BEA gene cluster, containing all four genes found in the cluster in F. fujikuroi. The BEA1 gene (NRPS22), sequence in F. temperatum was intact and the same as that found in F. fujikuroi and the other known BEA-producing species of Fusarium. The BEA1 gene of F. subglutinans, however, contained a unique 190 bp intron, absent in five BEA-producer species (Ff, Fp, Fm, Fo, Ft), and two SNPs that result in a truncated protein, based on ?in silico? protein translation analysis. We think that these differences suffice to keep F. subglutinans from producing BEA.This research was supported by the joint research project CNR-CONICET.