Fusarium chaquense,sp. nov, a novel type A trichothecene-producing species from native grasses in a wetland ecosystem in Argentina

Authors: NICHEA, MARIA - National University Of Rio Cuarto; Proctor, Robert; Probyn, Crystal; PALACIOS, SOFIA - National University Of Rio Cuarto; CENDOYA, EUGENIA - National University Of Rio Cuarto; SULYOK, MICHAEL - University Of Natural Resources & Applied Life Sciences - Austria; CHULZE, SOFIA - National University Of Rio Cuarto; TORRES, ADRIANA - National University Of Rio Cuarto; RAMIREZ, MARIA - National University Of Rio Cuarto

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2021
Publication Date: 12/6/2021
Citation: Nichea, M.J., Proctor, R., Probyn, C.E., Palacios, S.A., Cendoya, E., Sulyok, M., Chulze, S.N., Torres, A.M., Ramirez, M.L. 2021. Fusarium chaquense,sp. nov, a novel type A trichothecene-producing species from native grasses in a wetland ecosystem in Argentina. Mycologia. 114(1):46-62. https://doi.org/10.1080/00275514.2021.1987102.
DOI: https://doi.org/10.1080/00275514.2021.1987102

Interpretive Summary: Fungi can pose a dual threat to agriculture by producing toxins (mycotoxins) that are harmful to human and animal health and by causing plant diseases that reduce yield and quality of the harvested crops. Fungi that cause these agricultural problems originated on wild progenitors of modern crops or have more recently spread from wild plants to crops. To further investigate the relationships between fungi that occur on crops and on wild plants, we examined the diversity of fungi on grasses in a non-agricultural wetland in northern Argentina. The investigation led to identification of a novel species of Fusarium that produces mycotoxins known as trichothecenes, which are among the mycotoxins of most concern to agriculture. The novel species, Fusarium chaquense, is closely related to the cereal pathogens Fusarium langsethiae and F. sporotrichioides, which produce similar trichothecenes (e.g., T-2 toxin). F. chaquense is the third Fusarium species identified recently that produces these trichothecenes and that occurs on wild plants in a natural environment. The close relationship of these three species to F. langsethiae and F. sporotrichioides indicates the potential for spread of trichothecene-producing fungi from wild plants to crops. However, knowledge of the novel species also has potential to provide insight into how to control mycotoxin contamination and diseases caused by Fusarium species.

Technical Abstract: The Chaco wetland is among the most biologically diverse regions in Argentina. In collections of fungi from asymptomatic native grasses (Poaceae) from the wetlands, we identified isolates of Fusarium that were morphologically similar to F. armeniacum, but distinct from it by their production of abundant microconidia. All the isolates had identical, or nearly identical, partial sequences of TEF1 and RPB2. But they were distinct from reference sequences from F. armeniacum and Fusarium species closely related to it. Phylogenetic analysis of 34 full-length housekeeping gene sequences retrieved from whole genome sequences of three Chaco wetland isolates, 29 genes resolved the isolates as an exclusive clade within the F. sambucinum species complex. Based on results of the morphological and phylogenetic analysis, we concluded that the Chaco wetland isolates are a distinct and novel species, herein described as Fusarium chaquense, sp. nov., which is closely related to F. armeniacum. F. chaquense in culture can produce the trichothecenes T-2 and HT-2 toxin, neosolaniol, diacetoxyscirpenol, and monoacetoxyscirpenol, as well as beauvericin and the pigment aurofusarin. Genome sequence analysis also revealed the presence of three previously described loci required for trichothecene biosynthesis. This research represents the first study of Fusarium in a natural ecosystem in Argentina.