| Congresso Brasileiro de Microbiologia 2023 | Resumo: 758-1 | ||||
Resumo:Fusarium verticillioides is a fungus that mainly affects the corn crop, causing the disease known as ear rot, resulting in ear rot, reduced yield and production of mycotoxins, harmful to humans and animals consuming contaminated grains. The fungus Macrophomina phaseolina causes the disease known as charcoal rot in various crops such as beans and soybeans. The fungus primarily infects the roots and stem of plants, resulting in plant wilting and death. Both fungi represent significant challenges, requiring integrated management strategies to minimize their impacts on crop production. In most cases, these phytopathogenic fungi are controlled by agrochemicals, but excessive use negatively affects the environment and human health. In addition, these products can increase fungal resistance and affect beneficial microorganisms. Biological control emerges as a promising natural, safe, and ecologically viable alternative to control phytopathogens, besides reducing the harmful effects of agrochemicals. Thus, this work aimed to isolate microorganisms from rhizosphere soils and aerial root mucilage of sweet sorghum antagonists of F. verticillioides and M. phaseolina and proceed to their molecular identification by partial sequencing of the 16S rRNA gene. The antagonistic activity was tested in vitro by the Direct Confrontation Method in a solid medium, using 26 bacteria and 2 fungal isolates from the Collection of Multifunctional Microorganisms and Phytopathogens of Embrapa Maize and Sorghum (CMMF-MS). A 10 µL of bacterial suspension was added in four equidistant points from each other to the palate's center. Mycelial discs of each phytopathogen were added to the center of the plate, and the control consisted of plates containing only the phytopathogen. The fungal
colony radius was measured in the presence and absence of antagonistic microorganisms when the entire medium surface was colonized by the phytopathogen in the control treatment. Of the isolates tested for antagonism against F.verticillioides, 20 showed positive results, ranging from 6.98% to 57.36% of inhibition, whereas 13 isolates showed antagonism, ranging from 25.88% to 68.82% of inhibition against M. phaseolina. Of all isolates, five showed inhibition, more significant than 40% for both fungi. They are GSC-4 (57.36% and 59.41%), P. POLY (46.51% and 61.18%), SC1-8 (42.64% and 63.53%), TSC-5 (48.06% and 55.88%) and GSS7-34 (54.26% and 44.71%) for F. verticillioides and M. phaseolina, respectively. In conclusion, the tested bacteria exhibit antagonistic activity against F. verticillioides and M. phaseolina and represent promising candidates for studies aiming at developing bioproducts to control Fusarium verticillioides and Macrophomina phaseolina in the field. Palavras-chave: Biocontrol, Fungal Plant Diseases, Fungal Diseases, Fungal Antagonists Agência de fomento:Faped - Fundação de Apoia a Pesquisa e ao Desenvolvimento | |||||