Extrato etanólico de própolis na proteção de feijoeiro ao crestamento bacteriano comum

Abstract

Propolis is a resin produced by bees in the hive protecting function. The antimicrobial activity of the substance has already been proven, especially on human health. However, there are few studies concerning the action of propolis on plant pathogens. Thus, this study aimed to investigate the potential of propolis ethanolic extracts (PEE)originating from Paraná regions in the control of bacterial blight, a disease caused by the bacterium Xanthomonas axonopodis pv. phaseoli, as well as the resistance induction in bean. The experiment was conducted in laboratory and greenhouse, using the varietyIPR-Colibri. The PEE was evaluated at concentrations of 0.1; 0.5; 1; 2.5 and 5%, taking place of the Laranjeiras do Sul, Maringá and Marechal Cândido Rondon region. Antimicrobial activity assays were performed in vitro on bacteria and induction of phytoalexins, and in the local and systemic effect on disease severity in bean plants. The tests were conducted in a completely randomized design with four replications and subjected to analysis of variance and means compared by the Scott-Knott test at 5% probability, in addition to regression analysis. The results of in vitro assays were similar for the three regions, and presented in a linear equation. The test with the bacteria showed that the PEE 5% of Laranjeiras do Sul trees reduced the growth of X. axonopodis pv. phaseoli 97% over the control. In phaseolin induction, the concentrations of 5% of PEE autoclaved showed the highest accumulation in the three regions, with 45.67, 38.9 and 48.7% more than the distilled water, for Laranjeiras do Sul, Maringá and Marechal Cândido Rondon, respectively. The autoclaved extracts showed no significant difference while drastically reduced compared to non-autoclaved. The results obtained in the in vivo experiment showed reduction on the disease severity. The treated trefoil showed lower area injured at concentrations of 1 and 2.5% PEE, while the trefoil not treated had a lower area with the disease at concentrations 0.5 and 1% of the extract. These results indicate the potential of PEE from different regions of Paraná as a direct antimicrobial about X. axonopodis pv. phaseoli and phaseolin inductor in bean hypocotyls. With regard to plants, the PEE reduced the severity of the disease is by antimicrobial activity or resistance induction indicating potential for disease control.