| Congresso Brasileiro de Microbiologia 2023 | Resumo: 314-1 | ||||
Resumo:The genus Fusarium is considered one of the major contaminants of cereals and can act as a pathogen or endophyte of several host plants. The Fusarium sambucinum species complex (FSAMSC) stands out due to its high potential for producing mycotoxins, such as type A trichothecenes, type B trichothecenes (TRI), and zearalenone (ZEN). These species are recognized as one of the major contaminants of small grain cereals, such as barley, leading to agricultural losses due to grain damage and mycotoxin production. It is known that plants from natural ecosystems may harbour several pathogenic and/or toxigenic species of fungi, acting as a reservoir of these microorganisms, that can migrate to agroecosystems and colonize a susceptible host. In this context, native barley that occurs in the Pampa biome may play a key role in harbouring Fusarium species that may act as endophyte of this plant. The objective of this study was to assess the diversity of FSAMSC from Brazilian native barley and the structural and functional organization of the main genes responsible to produce TRI and ZEN of the isolates. These data were then compared with reference strains isolated from agroecosystems, to identify interactions between isolates from different ecosystems. Phylogenies were built based on RPB1, RPB2 and TRI5 using Geneious and PAUP softwares. Genomic analysis was conducted in CLC Genomic Workbench. After finding the respective gene clusters in the fungal genomes, synteny map was done in Clinker v0.0.27, though the respective alignment of .gbk extracted cluster sequences. Phylogenies demonstrated the occurrence of F. asiaticum, F. graminearum and F. cortaderiae in native barley, as well as F. armeniacum, a potential T-2 toxin producer. TRI5 phylogeny has shown that F. cortaderiae and F. asiaticum were closely related, despite these two lineages being distant based on RPB1 + RPB2 phylogeny, suggesting that a horizontal gene transfer event happened between these two isolates from natural ecosystem. Additionally, genomic study demonstrated a structural similarity of TRI gene cluster between F. cortaderiae and F. asiaticum, both able to produce nivalenol. F. cortaderiae presented all of the genes that belong to ZEN gene cluster, whereas F. asiaticum did not present a functional ZEB2, showing that F. cortaderiae may be able to produce ZEN, whilst the F. asiaticum strain cannot. F. armeniacum presented all the genes responsible for T-2 toxin production and these were structurally similar to the reference F. sporotrichioides TRI gene cluster, inidicating that this isolate was able to produce T-2 toxin. The results demonstrated that Brazilian native barley is acting as a reservoir of these fungi, capable of producing nivalenol and T-2 toxin, with the potential for migration of these strains to agroecosystems. Palavras-chave: Mycotoxins, Secondary Metabolism, Native Barley, Fungi, Biosynthetic Gene Cluster Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) e Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) | |||||