PURIFICATION AND CHARACTERIZATION OF TOXINS FROM WHEAT ISOLATES OF Drechslera tritici-repentis, Bipolaris bicolor, AND Bipolaris sorokiniana

Abstract

Low molecular weight metabolites produced by Bipolaris bicolor, Bipolaris sorokiniana, and Drechslera tritici-repentis are considered to be toxins that facilitate disease in wheat cultivars. Several such toxins were isolated from these fungi. Electrophoresis demonstrated bands of proteins that reduced shoot inhibition in susceptible plants but not in resistant plants. Chlorophyll content was reduced during the first 10 hours of light in the susceptible plants and after 18 hours in the resistant plants. The enzyme beta-1,3-glucanase increased in the resistant plants after treatment with toxins, but in the susceptible plants this enzyme decreased compared to the control. This suggests that the toxin was a protein and the susceptible plants needed other mechanisms for induced resistance

Induced Resistance against Bipolaris bicolor, Bipolaris sorokiniana and Drechslera tritici‐repentis in Wheat Leaves by Xantham Gum and Heat‐Inactivated Conidial Suspension

“…When the results were compared with those from the group of plants inoculated with the pathogens (C3), those plants with lesions presented decreased enzymatic activity (Table 7). These results are in agreement with those by Bach and Kimati (1999). However, in plants treated with xantham gum, higher enzyme activity was observed, correlated with the increase in the time interval between inducer and challenge.…”

“…However, toxin produced by B. sorokiniana affects the physiology of the membrane, leading to necrotic cell death. Bach and Kimati (1999), working with toxin produced by D. tritici‐repentis , B. bicolor and B. sorokiniana isolated from wheat, observed that it was a low molecular weight protein which, when in contact with susceptible wheat plants, led to a decrease in β ‐1,3 glucanase enzymatic activity, when compared with healthy plants. Thus, it was understood that some mechanism was activated in the susceptible host and acted on the cells, promoting postpenetration resistance.…”

Characterization of the brown leaf spots pathosystem in Brazilian pecan orchards: pathogen morphology and molecular identification

“…Toxins are products of microbial pathogens that can be produced both in affected tissues and in culture media (Bach et al 2005). Toxins can act in different sites at the cellular level, changing the permeability and/or the potential of membranes, impairing plant physiology (Bach & Kimati 1999). Bach et al (2005) demonstrated that the isolated application of toxins produced by Exserohilum turcicum (which causes northern corn leaf blight) caused necrosis in corn leaves.…”

Atividade antimicrobiana de fungos endofíticos isolados de plantas tóxicas da amazônia: Palicourea longiflora (aubl.) rich e Strychnos cogens bentham

“…Os microrganismos podem produzir uma variedade muito grande de metabólitos tanto primários quanto secundários, incluindo enzimas (Stamford et al, 1998), aminoácidos (Kleinkauf & Von Dohren, 1990), vitaminas, antibióticos, pigmentos (Demain, 1992), agentes moduladores de respostas imunológicas (Trilli et al, 1978), toxinas (Bach & Kimati, 1999), agentes anti-tumorais (Wang et al, 2000), fatores de crescimento de plantas (Alexopoulos, 1996), anti-helmínticos (Rodrigues et al, 2000) e anti-micóticos . Dos líquidos metabólicos das 79 linhagens de fungos endofíticos selecionadas para os ensaios de antagonismo in vitro, 19 (24,05%) apresentaram atividades antagônicas contra um ou mais microrganismo-teste utilizados nestes ensaios (Tabela 3; Figuras 1, 2 e 3).…”