In vitro toxin production by Fusarium solani f. sp. piperis

Abstract

Fusarium solani f. sp. piperis (teleomorph: Nectria haematococca f. sp. piperis), causal agent of root rot and stem blight on black pepper (Piper nigrum), produces secondary metabolites with toxigenic properties, capable of inducing vein discoloration in detached leaves and wilting in transpiring microcuttings. Production of F. solani f. sp. piperis (Fsp) toxic metabolites reached a peak after 25 days of static incubation on potato sucrose broth at 25 °C under illumination. Changes in the pH of the culture filtrate did not alter the effect of toxic metabolites. However, when the pH was changed before the medium had been autoclaved, a more intense biological response was observed, with an optimum at pH 6.0. Isolates that produced red pigments in liquid cultures were more efficient in producing biologically active culture filtrates than those which produced pink coloured or clear filtrates suggesting that these pigments could be related to toxigenic activity. Detached leaves of seven black pepper cultivars and Piper betle showed symptoms of vein discoloration after immersion in autoclaved and non-autoclaved Fsp culture filtrates indicating the thermostable nature of these toxic metabolites.Additional keywords: Secondary metabolites; resistance; black pepper; Piper betle. Produção de toxinas in vitro por Fusarium solani f. sp. piperisFusarium solani f. sp. piperis (teleomórfico: Nectria haematococca f. sp. piperis) agente causal da podridão-das-raízes e do secamento-dos-ramos da pimenteira-do-reino (Piper nigrum) produz metabólitos secundários com propriedades tóxicas capazes de induzir descoloração das nervuras em folhas destacadas e murcha em micro-estacas. A produção de metabólitos tóxicos alcançou o pico após 25 dias de incubação, sob iluminação. Variações no pH do filtrado da cultura não aumentaram o efeito tóxico, entretanto, quando o pH foi ajustado antes da esterilização do meio de cultura, uma RESUMO resposta biológica mais intensa foi observada, atingindo o máximo em pH 6,0. Isolados que produziram pigmentos vermelhos no meio de cultura foram mais eficientes em produzir filtrados biologicamente ativos do que aqueles que produziram filtrados de coloração rósea ou branca sugerindo que estes pigmentos podem estar relacionados com atividade toxigênica. Folhas destacadas de sete cultivares de pimenta-do-reino e Piper betle exibiram sintomas de descoloração das nervuras após imersão em filtrados autoclavado e não-autoclavado indicando a natureza termoestável destes metabólitos tóxicos.

Toxic thermoresistant metabolites of Fusarium oxysporum are capable of inducing histopathological alterations in Wistar rats

“…The Czapeck-dox liquid medium, which is chemically defined, was suitable for stimulating the production of this type of metabolite produced by Fusarium, in accordance with reports by other investigators (18)(19)(20)(21)(22)(23)(24)(25).…”

“…Fungus producers of colored pigments in liquid cultures were more efficient at producing filtrates from biologically active cultures than those that did not produce color, suggesting that these pigments may be involved in the toxigenic action (24).…”

“…There is a consensus that fungi, during their development in the host tissues or in culture media, may produce a variety of toxic secondary metabolites with varied biochemical structures and different action modes, including polypeptides, glycoproteins, amino acid derivatives, polyketides, terpenoids, sterols and quinines (24). The Czapeck-dox liquid medium, which is chemically defined, was suitable for stimulating the production of this type of metabolite produced by Fusarium, in accordance with reports by other investigators (18)(19)(20)(21)(22)(23)(24)(25).…”

Allelopathic effects of pathogenic fungi on weed plants of soybean and corn crops

“…The cultures were double filtered on double gauze for mycelium removal, and then sterilized through a Millipore membrane (0.45 µm), with a filter system under vacuum for spores removal (crude culture filtrate). This methodology was adapted from Duarte and Archer (2003) and Viecelli et al (2009).…”

Atividade alelopática do filtrado de cultura produzido por Fusarium solani

“…A fim de estimular a produção de toxinas, os frascos foram envolvidos com papel-alumínio e mantidos estáticos, em ambiente de laboratório. As culturas foram filtra das em dupla gaze, para eliminação de micélio, e por um disco de papel-de-filtro qualitativo, usando-se funil de Buchner, sob vácuo, para eliminação de esporos (Duarte & Archer, 2003). Posteriormente, o filtrado da cultura foi submetido ao processo de liofilização.…”