Papel funcional de fungos endofíticos isolados de Vochysia divergens

Abstract

Populations of Vochysia divergens have expanded in the multiannual flooding period of the Neotropical wetland, being their distribution correlated to the water regime and the acidity of the soil. High concentrations of aluminum can be harmful to the development of seedlings of this specie, that has low resistance to drought. A strategy used by plant species to confer tolerance to stressful environments is the association with endophytic fungi, which are characterized by an asymptomatic colonization of their host. The present study aims to investigate the possible relationship between endophytic fungi and tolerance of V. divergens to stress caused by high concentrations of aluminum and drought. Growth parameters from seedlings submitted to stress were observed in vitro, such as length and biomass of the shoot and root, the number of secondary roots, as well as the activity of antioxidant enzymes. Endophytic fungi isolated from V. divergens’ root were evaluated for mycelial growth rate in culture media enriched with different concentrations of Al just as in medias simulating water restriction. The ability of indoleacetic acid synthesis and phosphate solubilization was also investigated in vitro. Model vegetable species (Sorghum bicolor and Oryza sativa) were used to investigate the potential of endophytic lineages to mitigate water stress. Growth parameters, chlorophyll content and fluorescence rates were measured. The V. divergens seedlings presented growth and development restrictions under stress due to water deficit and high Al concentration exposure. Endophytic strains Phialocephala sp.-v1 and D. phaseolorum-v43 presented tolerance to aluminum, however, they did not promote stress mitigation in V. divergens seedlings. F. oxysporum-v47 and S. cucurbitacearum-v12 strains showed potential in the synthesis of AIA and phosphate solubilization, respectively, both of which presented tolerance to water stress. In general, it can be said that the isolated endophytic strains of V. divergens has not mitigating stress effect in this experimental models evaluated.