Species of the Fusarium incarnatum-equiseti species complex associated with panicles of pearl millet and potential for mycotoxin production.

Pearl millet is an expanding crop in Brazil, used as a cover crop and destined for animal food. Fusarium species colonize the panicle and may cause head mold or compromise the safety of grains by producing mycotoxins. We collected samples of panicles from different producing regions of Brazil with and without signs of Fusarium infection to investigate which species are associated with panicles and their potential for producing mycotoxins. A total of 154 Fusarium isolates were obtained and assigned to three species complexes (SC) based on morphology. Fusarium incarnatum-equiseti SC was dominant and obtained from all samples, followed by F. fujikuroi SC and F. chlamydosporum SC. Six phylogenetic species were identified in FIESC (F. caatingaense, F. hainanense, F. incarnatum, F. neosemitectum, F. pernambucanum and F. sulawesiense), two in FFSC (F. brachiariae and F. verticillioides) and one in FCSC (F. chlamydosporum). In in vitro analyses, selected strains of F. hainanense produced zearalenone (ZEN), deoxynivalenol (DON) and fusarenon-X (FX), F. incarnatum and F. neosemitectum produced ZEN and DON, F. pernambucanum and F. sulawesiense produced DON, while F. caatingaense did not produce any mycotoxin. None of the strains produced 3-ADON, 15-ADON, nivalenol (NIV) or diacetoxyscirpenol (DAS). Within a biased selection of 19 grain samples with signs of mold analyzed, almost half showed some natural contamination with ZEN, while NIV was detected in one sample. DON, 3-ADON, 15-ADON and fumonisins FB1 and FB2 were not detected. This is the first report of occurrence of F. neosemitectum in Brazil and on cereals worldwide. Our results expand the knowledge of Fusarium species infecting panicles and causing head mold in pearl millet and emphasizes the need for monitoring and mitigating the risk of contamination with mycotoxins, especially ZEN.