Differences in the beauvericin gene cluster and toxin production in Fusarium subglutinans and Fusarium temperatum

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

Ghent

Congreso; 1st MYCOKEY International Conference Global Mycotoxin Reduction in the Food and Feed Chain; 2017

Universidad de Ghent -Mycokey Project

Beauvericin (BEA) is a secondary metabolite producedby many species of Fusarium. F. circinatum, F. fujikuroi, F. mangiferae, F. nygamai, F. proliferatum, F. sacchari, F.oxysporum and F. temperatum areproducers, 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 contaminatedwith BEA. Beauvericin is a cyclichexadepsipeptide that incorporates into biological membranes where it complexeswith essential cations, increasing membrane permeability and altering cellularhomeostasis. BEA iscytotoxic to some cell lines in vitroand potentially genotoxic to human lymphocytes, whereit is associated with chromosomal aberrations. Genes encoding BEA biosynthesis were first describedfor 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 peptidesynthase (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 indistinguishablebased solely on morphology. BEA production distinguishes these species,however, as F. temperatum can produceBEA but F. subglutinans cannot. We recovered 25 Fusarium strains from maize harvested inArgentina. Based on partial EF-1a, b-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 strainsproduced BEA, while 9/12 of the F.temperatum strains produced BEA atbetween 7 and 400 µg/g. Genomic comparison of two species highlighted for the first time the presencein both species of BEA gene cluster, containing all four genes found in thecluster in F. fujikuroi. The BEA1 gene (NRPS22), sequence in F. temperatum was intact and the same asthat found in F. fujikuroi and theother known BEA-producing species of Fusarium.The BEA1 gene of F. subglutinans, however, contained a unique 190 bp intron, absentin five BEA-producer species (Ff, Fp, Fm, Fo, Ft), and two SNPs that result in atruncated 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 jointresearch project CNR-CONICET.