Venenos e toxinas ofídicas purificadas como ferramenta biotecnológica para o controle de Ralstonia solanacearum

The objective of this work was to evaluate the in vitro antibacterial activity of snake venoms and purified toxins on the phytopathogenic bacterium Ralstonia solanacearum. The evaluations were performed with 17 crude venoms (13 from Bothrops, 3 from Crotalus, and 1 from Lachesis) and seven toxins (1 from Bothrops and 6 from Crotalus). Antibacterial activity was assessed in MB1 medium containing solubilized treatments (1 μL mL‑1). A total of 100 μL bacterial suspension (8.4 x 109 CFU mL-1) was used. After incubation at 28°C, the number of bacterial colonies at 24, 48, and 72 hours after inoculation was evaluated. SDS-PAGE gel at 15% was used to analyze the protein patterns of the samples, using 5 μg protein of each sample in the assay. Furthermore, the minimum inhibitory concentration (MIC) and lethal concentration (LC50) values were determined by the Probit method. Venoms and toxins were able to reduce more than 90% of R. solanacearum growth. These results were either equivalent to those of the positive control chloramphenicol or even better. While MIC values ranged from 4.0 to 271.5 µg mL-1, LC50 ranged from 28.5 µg mL-1 to 4.38 mg mL-1. Ten crude venoms (7 from Bothrops and 3 from Crotalus) and two purified toxins (gyroxin and crotamine) are promising approaches to control the phytopathogenic bacterium R. solanacearum.O objetivo deste trabalho foi avaliar a atividade antibacteriana in vitro de venenos e toxinas purificadas de serpentes sobre a bactéria fitopatogênica Ralstonia solanacearum. As avaliações foram realizadas em 17 venenos brutos (13 de Bothrops, 3 de Crotalus e 1 de Lachesis) e sete toxinas (1 de Bothrops e 6 de Crotalus). A atividade antibacteriana foi avaliada em meio MB1 que continha os tratamentos solubilizados (1 μL mL-1). Utilizou-se o total de 100 μL de suspensão bacteriana (8,4 x 109 UFC mL-1). Após incubação a 28°C, avaliou-se o número de colônias bacterianas às 24, 48 e 72 horas após a inoculação. O gel SDS-PAGE a 15% foi usado para analisar o perfil proteico das amostras, tendo-se utilizado 5 μg de proteína no ensaio. Além disso, os valores de concentração inibitória mínima (CIM) e concentração letal (CL50) foram determinados pelo método Probit. Os venenos e as toxinas foram capazes de reduzir mais de 90% do crescimento de R. solanacearum. Esses resultados foram ou equivalentes aos do controle positivo cloranfenicol ou até melhores. Enquanto os valores de CIM variaram de 4,0 a 271,5 µg mL-1, a CL50 variou de 28,5 µg mL-1 a 4,38 mg mL-1. Dez venenos brutos (7 de Bothrops e 3 de Crotalus) e duas toxinas (giroxina e crotamina) são abordagens promissoras para o controle da bactéria fitopatogênica R. solanacearum

Antifungal Activity of Hedychium Coronarium j. König Essential Oil Against Fusarium Oxysporumschlecht and Tcucumeris (a.b. frank) Donk in Vitro

Fusarium oxysporum Schlecht and Thanatephorus cucumeris (A.B. Frank) Donk are fungi which cause some diseases in important plant cultures in Brazil - like bananas and beans. Hedychium coronarium J. König is a native plant from Asia that currently occurs in Brazil, where it is used in folk medicine to treat infections in general. The objective of this work was to evaluate the effect of the H. coronarium essential oil from leaves on the in vitro growth of F. oxysporum and T. cucumeris colonies. Discs of 5 mm diameter from isolated cultures of each fungi were placed in the center of 90 mm diameter Petri dishes with potato dextrose agar. In the peripheral area of the dishes four discs of filter paper were placed with 10 µL of essential oil, extracted through distillation system. For a control treatment, discs without essential oil were used. A completely randomized design was used with four replications (of four dishes). Every 24 hours for 8 days the fungi growth was evaluated by measuring the diameter of the colonies. After 192 hours F. oxysporum colonies had 37.4 mm diameter in the treatment with essential oil, while in the control the diameter was 66.4 mm. T. cucumeris colonies reached 11.9 mm diameter with essential oil and covered the dishes in the control. The results showed that the essential oil from leaves of H. coronarium has an inhibitory effect on the in vitro growth of F. oxysporum and T. cucumeris, thus suggesting its potential use in agriculture, mainly with respect to banana and bean cultures. Keywords: phytopathology, medicinal plants, biological control.http://dx.doi.org/10.5902/2179460X13118Fusarium oxysporum Schlecht and Thanatephorus cucumeris (A.B. Frank) Donk are fungi which cause some diseases in important plant cultures in Brazil - like bananas and beans. Hedychium coronarium J. König is a native plant from Asia that currently occurs in Brazil, where it is used in folk medicine to treat infections in general. The objective of this work was to evaluate the effect of the H. coronarium essential oil from leaves on the in vitro growth of F. oxysporum and T. cucumeris colonies. Discs of 5 mm diameter from isolated cultures of each fungi were placed in the center of 90 mm diameter Petri dishes with potato dextrose agar. In the peripheral area of the dishes four discs of filter paper were placed with 10 µL of essential oil, extracted through distillation system. For a control treatment, discs without essential oil were used. A completely randomized design was used with four replications (of four dishes). Every 24 hours for 8 days the fungi growth was evaluated by measuring the diameter of the colonies. After 192 hours F. oxysporum colonies had 37.4 mm diameter in the treatment with essential oil, while in the control the diameter was 66.4 mm. T. cucumeris colonies reached 11.9 mm diameter with essential oil and covered the dishes in the control. The results showed that the essential oil from leaves of H. coronarium has an inhibitory effect on the in vitro growth of F. oxysporum and T. cucumeris, thus suggesting its potential use in agriculture, mainly with respect to banana and bean cultures

Componentes primários e secundários do rendimento de óleo de pinhão-manso Primary and secondary yield components of the oil in physic nut (Jatropha curcas L.)

A definição dos critérios para seleção de materiais é especialmente importante para o cultivo do pinhão-manso (Jatropha curcas L.), pois subsidia a caracterização dos ideótipos mais adequados para o plantio e o progresso genético com a prática da seleção. O objetivo deste trabalho foi estimar, por meio de análise de trilha com diagrama em cadeia, os efeitos diretos e indiretos de sete características vegetativas e quatro características de qualidade da matéria-prima sobre o rendimento de óleo de pinhão-manso com 38 meses de cultivo. A produtividade de grãos e o teor de óleo apresentaram efeito direto e positivo sobre o rendimento de óleo, e o volume de copa mostrou-se como um dos principais componentes de efeito indireto e positivo sobre a variável principal. Na população de melhoramento avaliada, as estimativas dos efeitos diretos e indiretos indicaram que a seleção de plantas de maior rendimento de óleo deve considerar genótipos de maior produtividade de grãos e maior volume de copa, mantendo-se a variabilidade para as outras características avaliadas.The definition of the most suitable plant selection criteria is especially important for Jatropha curcas L. as subsidies the genetic progress estimates and the ideotype characterization, described in terms of the traits that are thought to enhance genetic yield potential. The objective of this study was to estimate the direct and indirect effects of seven vegetative traits and four seed quality traits on J. curcas oil yield. The traits grain yield and the weight of the nuts showed direct and positive effect on the oil yield. The tree volume showed the major indirect and positive effect on the main variable through grain yield. The development of J. curcas with higher oil yield in the evaluated population has to consider the selection of plants with higher yield and tree volume, maintaining the variability of the grain quality traits