RESUMO
This study aimed to identify four isolates of Trichoderma sp. (Ufra.T06, Ufra.T09, Ufra.T12, and Ufra.T52) and characterize their interaction with Magnaporthe oryzae in vitro and in vivo conditions. The four isolates of Trichoderma sp. were sequenced, investigated as an antagonist against M. oryzae in five Petri plate assays, and as an inhibitor of conidial germination appressoria formation. Finally, were quantified the lytic activity of chitinase (CHI), glucanase (GLU), and protease (PRO) during co-cultivation of Trichoderma sp. and M. oryzae. In vivo, leaf blast suppression was evaluated in two assays: simultaneous and curative application. Both in vitro and in vivo assays were scanned by electron microscopy (SEM). All isolates were identified as Trichoderma asperellum. All in vitro Petri plates assays reduced M. oryzae colony growth (paired-91.18% by Ufra.T09, volatile metabolites-all isolates equally reduced, non-volatile-68.33% by Ufra.T06, thermostability-99.77% by Ufra.T52 and co-cultivate-64.25% by Ufra.T52). The filtrates and conidia suspensions for T. asperellum isolates inhibited the conidia germination and appressoria formation significantly. In co-cultivate (mycelial or cell wall), all enzymes (GLU, CHI, and PRO) and times (24, 48, and 72 h) showed increased activity. In vivo, reduced leaf blast severity until 94.64% (Ufra.T52cs) in a simultaneous and until 85% (Ufra.T09 24 and 48 hasi) in a curative application. T. asperellum isolates showed efficient control of M. oryzae by mycoparasitism, and antibiosis mechanisms were interfered with by the M. oryzae infection process.
Assuntos
Antibiose , Ascomicetos , Hypocreales , Oryza , Ascomicetos/fisiologia , Ascomicetos/ultraestrutura , Hypocreales/genética , Hypocreales/ultraestrutura , Oryza/microbiologia , Doenças das Plantas/microbiologiaRESUMO
The entomopathogenic anamorphic genus Evlachovaea was described to differ from other fungi in forming its conidia obliquely to the axis of the conidiogenous cell and with successive conidia having alternate orientations with a zipper- or chevron-like arrangement resulting in flat, ribbon-like chains. Morphological and molecular studies of six Evlachovaea-like isolates baited from Central Brazilian soils using Triatoma infestans (a vector of Chagas disease) and of other entomopathogens with Evlachovaea-like conidiogenesis led to a re-evaluation of the status of this little known fungal genus. The Brazilian isolates formed two distinct groups based on gene sequences for both the internal transcribed spacer (ITS) and translation elongation factor (EF-1α) genes, morphology, and growth patterns; both groups also differed from the type species, Evlachovaea kintrischica. More detailed studies of these fungi indicated that the alternatingly oblique orientations of forming conidia are neither a stable nor invariant character (even on single phialides). Furthermore, the molecular cladistic analysis unambiguously placed the Evlachovaea isolates firmly within the genus Isaria (Hypocreales: Cordycipitaceae). The ITS sequences of E. kintrischica were very similar or even identical to those of Isaria amoenerosea and Isaria cateniobliqua, thereby suggesting that E. kintrischica is a synonym of one of these species, and that the genus Evlachovaea must be treated as a later synonym of Isaria, which must now be recognized to include several highly divergent modes of conidiogenesis. These taxonomic findings are discussed in the context of dramatic changes recently imposed on the nomenclatural standards used to determine the correct names of all pleomorphic fungi.
Assuntos
Hypocreales/classificação , Hypocreales/ultraestrutura , Análise de Sequência de DNA/métodos , Esporos Fúngicos/ultraestrutura , Animais , Brasil , DNA Fúngico/análise , Hypocreales/genética , Hypocreales/crescimento & desenvolvimento , Técnicas de Tipagem Micológica , Filogenia , Microbiologia do Solo , Triatoma/classificaçãoRESUMO
Five species of perithecial ascomycetes obligately infect the developing sporophytes of epiphyllous hepatics (Marchantiophyta, Porellales, Lejeuneaceae and Radulales, Radulaceae) while they are still enclosed by the calyptra and the perianth. These ascomycetes belong to the Hypocreales, which are especially well represented among the hyperepiphyllous fungi. The small and mostly brightly colored ascomata arise within the perianths and perforate its walls to discharge the ascospores. Conidiomata may be present as well. Colonization of the perianths prevents normal sporophyte development, sometimes causing deformities, while the foliose gametophyte remains unaltered. The fungus simultaneously can behave biotrophically toward the gametophyte and necrotrophically toward the sporophyte. Host fertility may be considerably reduced. Anthonectria mammispora is described as a new unispecific genus and Ticonectria testudinea as a new species. Ticonectria testudinea and presumably other species attack the region of the gametophyte-sporophyte junction including the transfer cells. The perianth-inhabiting fungi occupy one of the most distinct and nutrient-rich microniches in bryophytes. They are sex- and organ-specific and seem to be restricted to certain hosts but are not poor in characters as are many bryophilous fungi. These species increase the complexity of the phyllosphere.
Assuntos
Hepatófitas , Hypocreales/isolamento & purificação , Doenças das Plantas/microbiologia , Costa Rica , Hypocreales/ultraestrutura , Microscopia Confocal , Microscopia de Contraste de FaseRESUMO
The ovicidal activity of the nematophagous fungi Pochonia chlamydosporia (isolates VC1 and VC4), Duddingtonia flagrans (isolate AC001) and Monacrosporium thaumasium (isolate NF34) on Taenia saginata eggs was evaluated under laboratory conditions. T. saginata eggs were plated on 2% water-agar with fungal isolates and controls without fungus and examined after 5, 10 and 15 days. At the end of the experiment P. chlamydosporia showed ovicidal activity against T. saginata eggs (p<0.05), mainly for internal egg colonization with results of 12.8% (VC1) and 2.2% (VC4); 18.1% (VC1) and 7.0% (VC4); 9.76% (VC1) and 8.0% (VC4) at 5, 10 and 15 days, respectively. The other fungi showed only lytic effect without morphological damage to the eggshell. Results demonstrated that P. chlamydosporia was effective in vitro against T. saginata eggs unlike the other fungi.
Assuntos
Hypocreales/fisiologia , Taenia saginata/microbiologia , Animais , Ascomicetos/fisiologia , Ascomicetos/ultraestrutura , Humanos , Hypocreales/ultraestrutura , Microscopia Eletrônica de Varredura , Óvulo/microbiologia , Controle Biológico de Vetores , Taenia saginata/ultraestrutura , Fatores de TempoRESUMO
Chronological histological alterations of Metarhizium anisopliae during interaction with the cattle tick Boophilus microplus were investigated by light and scanning electron microscopy. M. anisopliae invades B. microplus by a process which involves adhesion of conidia to the cuticle, conidia germination, formation of appressoria and penetration through the cuticle. Twenty-four hours post-infection conidia are adhered and germination starts on the surface of the tick. At this time, the conidia differentiate to form appressoria exerting mechanical pressure and trigger hydrolytic enzyme secretion leading to penetration. Massive penetration is observed 72 h post-inoculation, and after 96 h, the hyphae start to emerge from the cuticle surface to form conidia. The intense invasion of adjacent tissues by hyphae was observed by light microscopy, confirming the ability of M. anisopliae to produce significant morphological alterations in the cuticle, and its infective effectiveness in B. microplus.
Assuntos
Hypocreales/crescimento & desenvolvimento , Hypocreales/ultraestrutura , Ixodidae/microbiologia , Ixodidae/ultraestrutura , Controle Biológico de Vetores , Animais , Bovinos , Doenças dos Bovinos/parasitologia , Doenças dos Bovinos/prevenção & controle , Hifas/crescimento & desenvolvimento , Hifas/ultraestrutura , Microscopia Eletrônica de Varredura/métodos , Infestações por Carrapato/parasitologia , Infestações por Carrapato/prevenção & controle , Infestações por Carrapato/veterináriaRESUMO
The entomopathogenic fungus Metarhizium anisopliae contains three superoxide dismutases. One of these enzymes was purified and partially characterized as a CuZnSOD. The enzyme has an estimated molecular mass of 30690 Da and a specific activity of 3838.89 Umg(-1). SDS-PAGE and 2D gels show a single band of protein in the fractions eluted from the gel filtration column with a molecular mass of 20000 and approximately 15000 Da, respectively, and a pI of 6.0. These results suggest that the native enzyme is a dimer consisting of two subunits. Polyclonal antiserum were raised against purified CuZnSOD and used to determine its subcellular localization by immunoelectron microscopy. M. anisopliae CuZnSOD is present in the cell wall.
Assuntos
Cobre/metabolismo , Hypocreales/enzimologia , Superóxido Dismutase/isolamento & purificação , Parede Celular/química , Hypocreales/genética , Hypocreales/ultraestrutura , Microscopia Imunoeletrônica , Superóxido Dismutase/química , Superóxido Dismutase/metabolismoRESUMO
Metarhizium anisopliae infects insects and ticks via a combination of specialized structures and cuticle degradation. Hydrolytic enzymes are accepted as key factors for the penetration step. The search for pathogenicity determinants has demonstrated that the process is multifactorial. Host specificity is an important factor to be addressed. The study of the enzymes produced during infection is important to discover those with a role in the process. To address some of the enzymes that take part during the infection of the tick, Boophilus microplus, we have analyzed the secretion of proteases and chitinases in single and combined carbon/nitrogen sources as compared with such complex substrates as chitin and B. microplus cuticles. Two chitinases, endo- and N-acetylglucosaminidases, and two proteases, subtilisin and trypsin-like proteases, were analyzed. Enzyme activities were detected in all carbon sources tested, but higher levels were found when combinations of carbon sources were used. A major 30-kDa protein apparently secreted during M. anisopliae growth on all carbon/nitrogen sources tested was demonstrated by SDS-PAGE.