FUSARIUM SPECIES AND MYCOTOXINS PRESENT ON NATIVE GRASSES FROM A WETLAND ECOSYSTEM IN ARGENTINA

NICHEA, M.J; SULYOK, M; KRSKA, R; CHULZE , S.N; TORRES A.M.; RAMIREZ M.L.

Martina Franca

Congreso; 13th European Fusarium Seminar; 2015

ISPA CNR ISM

Fusarium is globally one of most important genera of fungi, causing an array of plant diseases, producing mycotoxins and adversely affecting animal and human health. Some Fusarium species are associated with grasses, as saprophytes, endophytes or pathogens.  The aim of the present study was to evaluate the biodiversity of Fusarium species and also the natural occurrence of their mycotoxins in native grasses collected from a wetland ecosystem located in the Chaco, Argentina. This region is one of the three highest biodiversity biomes of Argentina and covers part of the Parana and Paraguay rivers floodplain complex in the Eastern border of Chaco Province. The landscape is complex open water, aquatic vegetation, grasslands and gallery forests. This temperate grassland is used for grazing cattle. A total of 70 grasses belonging to 12 different genera all included in the Poaceae family were collected at two different periods of the year (Summer and Spring). The mycological analysis of the grasses revealed that all the samples were contaminated with Fusarium species in levels ranging from 60 to 100% regardless the grass genera and the time of sampling analysed. The most common species found was F. armeniacum (50 to 100%). The species identity of 80 isolates morphologically identified as F. armeniacum was confirmed by translation elongation factor-1α gene sequencing. Other species found at very low frequencies were F. semitectum, F. chlamydosporum, F. sporotrichioides and some species belonging to the Gibberella fujikuroi species complex (F. verticillioides, F. subglutinans, F. proliferatum and F. beomiforme). Most of the samples (98%) showed mycotoxin contamination, with zearalenone (ZEA), T-2 toxin, beauvericin (BEA), HT-2 toxin and aurofusarium (AUF) being most prevalent. Other Fusarium mycotoxins found in low frequency were neosolaniol (NEO) and diacetoxiscirpenol (DAS). We did not observe differences in the mycotoxin types and levels between the different grass genera and the time of sampling. The metabolite pattern was previously expected to some extent as we have demonstrated that F. armeniacum is able to produce mainly trichothecene type A, ZEA, BEA and AUF. The results suggest that important mycotoxins in terms of animal health are present all year long on the grassland used for grazing cattle.