# Characterization of Members of the Fusarium incarnatum–equiseti Species Complex from Natural and Cultivated Grasses Intended for Grazing Cattle in Argentina

## TL;DR

This study identifies diverse Fusarium species in Argentine grasses that can produce a mycotoxin linked to cattle contamination.

## Contribution

The study reveals high genetic diversity within the FIESC and confirms their ZEA production potential in pasture grasses.

## Key findings

- Phylogenetic analysis identified five known FIESC species and six putative new species.
- 76% of isolates produced zearalenone (ZEA), including in high quantities.
- FIESC species in Argentine grasses are likely sources of ZEA contamination in grazing cattle.

## Abstract

The detection of zeranol in grazing cattle could be explained by the metabolization of the mycotoxin, zearalenone (ZEA), which was proven to be naturally contaminating the grasses harboring the Fusarium species. Previous studies have suggested that members of the Fusarium incarnatum–equiseti species complex (FIESC) could be responsible for this contamination. Therefore, the objective of this study is to determine the species composition of FIESC isolates isolated from natural and cultivated pastures previously intended for livestock feed in Argentina and to analyze their ability to produce ZEA. Twenty-five Fusarium isolates were characterized by a phylogenetic analysis of the translation elongation factor 1α, and their ZEA production was quantified by cultivation in rice and subsequent analysis by UPLC-MS/MS. The phylogenetic analysis revealed a high genetic diversity identifying five isolates as species already described in the FIESC and six linages which could represent putative new phylogenetic species. In addition, 76% of the isolates were able to produce ZEA, even in high quantities. In conclusion, grasses used for grazing cattle in Argentina harbor a high diversity of FIESC species, many of which are potentially new and capable of producing ZEA, confirming their role as a likely source of this mycotoxin contamination in pastures and improving our understanding of mycological risk in livestock production systems.