Isolamento e identificação de Fusarium graminearum em plantações de trigo na região sudoeste do Paraná e adaptações nutricionais e físicas de meios de cultura para indução de macroconídios e produção de micotoxinas

Abstract

Wheat crops contributes significantly to the Brazil’s economic growth as it serves as raw material for food and feedstuffs. The state of Paraná stands out in wheat production due to the favorable climate. However, important diseases such as fusariosis, caused mainly by the fungus Fusarium graminearum Schwabe, affect these crops, damaging the production and contaminating the grains with mycotoxins harmful to human health, especially the deoxynivalenol. In view of this problem, the present research aims to isolate, identify and characterize the F. species in wheat samples and promote medium/substrate culture for induction of macroconidia and mycotoxins. A total of 19 wheat samples were collected in the southwest of Paraná and evaluated for the presence of F. graminearum. The morphological analyzes were used leaf of Eucalyptus-BDA, as a way to identify a species of interest through the presence of macroconidia and mycotoxins. Once identified, as isolated colonies of F. graminearum and a control strain, were found in two stages of incubation, one with the presence of oxygen and another without the presence of oxygen, totaling 20 pots for each treatment. This stage served for the standardization of cultures for the mycotoxigenic investigation of the isolates. The results obtained with the medium Eucalyptus-BDA were very satisfactory, since it induced a sporulation and consequently a production of macroconidia. The data obtained in the rice cultivation in the oxygen treatment in comparison to the non-oxygen treatment showed that the presence of this gas is an extremely important factor for the development of the fungi, since in the oxygen treatment the fungi grew throughout the crop and without oxygen there was no mycelial growth. It is concluded that all sampled areas of wheat crops were contaminated by the phytopathogenic and toxicogenic fungus F. graminearum, and it is necessary to carry out the proper maintenance of the grains in order to minimize the presence of biotic contaminants, since they are mycotoxin producers. The technique of induction of sporulation for the cascade of macroconides used is the plan of eucalyptus, it is an alternative to the use of a sporulation tool of fungi. In addition, cultivation of F. graminearum in rice for potential production of mycotoxins was satisfactory once the fungus developed. To obtain theinformation, the analysis of mycotoxin production in a rice standardized culture should be quantified by high performance liquid chromatography analysis.