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Hyphal Cells (hyphal + cell)
Selected AbstractsActivity and mode of action against fungal phytopathogens of bovine lactoferricin-derived peptidesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006A. Muñoz Abstract Aim:, To evaluate the activity against fungal phytopathogens of two synthetic peptides derived from the protein bovine lactoferricin: the antibacterial active core of six amino acid residues (LfcinB20,25) and an extension of 15 amino acids (LfcinB17,31). Methods and Results:,In vitro activity against fungal pathogens was determined and compared with that against model micro-organisms. Activity was demonstrated against fungi of agronomic relevance. Distinct antimicrobial properties in vitro were found for the two peptides. LfcinB17,31 had growth inhibitory activity higher than LfcinB20,25. However, LfcinB17,31 was not fungicidal to quiescent conidia of Penicillium digitatum at the concentrations assayed, while LfcinB20,25 killed conidia more efficiently. Microscopical observations showed that the mycelium of P. digitatum treated with LfcinB17,31 developed alterations of growth, sporulation and chitin deposition, and permeation of hyphal cells. In experimental inoculations of mandarins, both peptides showed limited protective effect against the disease caused by P. digitatum. Conclusions:, LfcinB20,25 and LfcinB17,31 peptides were shown to have antimicrobial activity against plant pathogenic filamentous fungi, with distinct properties and mode of action. Significance and Impact of the Study:, LfcinB20,25 and LfcinB17,31 peptides offer novel alternatives to develop resistant plants by molecular breeding. [source] Immunolocalization of 1,3-,-Glucanases Secreted by Gaeumannomyces graminis var. tritici in Infected Wheat RootsJOURNAL OF PHYTOPATHOLOGY, Issue 5 2010Yongting Yu Abstract The distribution of extracellular 1,3-,-glucanase secreted by Gaeumannomyces graminis var. tritici (Ggt) was investigated in situ in inoculated wheat roots by immunogold labelling and transmission electron microscopy. Antiserum was prepared by subcutaneously injecting rabbits with purified 1,3-,-glucanase secreted by the pathogenic fungus. A specific antibody of 1,3-,-glucanase, anti-GluGgt, was purified and characterized. Double immunodiffusion tests revealed that the antiserum was specific for 1,3-,-glucanase of Ggt, but not for 1,3-,-glucanase from wheat plants. Native polyacrylamide gel electrophoresis of the purified and crude enzyme extract and immunoblotting showed that the antibody was monospecific for 1,3-,-glucanase in fungal extracellular protein populations. After incubation of ultrathin sections of pathogen-infected wheat roots with anti-1,3-,-glucanase antibody and the secondary antibody, deposition of gold particles occurred over hyphal cells and the host tissue. Hyphal cell walls and septa as well as membranous structures showed regular labelling with gold particles, while few gold particles were detected over the cytoplasm and other organelles such as mitochondria and vacuoles. In host tissues, cell walls in contact with the hyphae usually exhibited a few gold particles, whereas host cytoplasm and cell walls distant from the hyphae were free of labelling. Furthermore, over lignitubers in the infected host cells labelling with gold particles was detected. No gold particles were found over sections of non-inoculated wheat roots. The results indicate that 1,3-,-glucanase secreted by Ggt may be involved in pathogenesis of the take-all fungus through degradation of callose in postinfectionally formed cell wall appositions, such as lignitubers. [source] Potential of Trichoderma harzianum and T. atroviride to Control Botryosphaeria berengeriana f. sp. piricola, the Cause of Apple Ring RotJOURNAL OF PHYTOPATHOLOGY, Issue 4-5 2002G. KEXIANG Abstract Trichoderma harzianum T88 and T. atroviride T95 were tested for their efficacy in controlling apple ring rot (caused by Botryosphaeria berengeriana f. sp. piricola) in vitro and in the field. Isolates of T88 and T95 produced both volatile and non-volatile antibiotics that suppressed mycelial growth of the pathogen. Light and scanning electron microscopy showed that mycoparasitism by Trichoderma spp. of B. berengeriana f. sp. piricola resulted in penetration and disruption of hyphal cells, and thinning of cytoplasm of the pathogen. The culture filtrates of T88 and T95 in Czapek's liquid medium suppressed conidial germination of the pathogen, and the germination level was negatively correlated with the duration of culture of Trichoderma. In inoculation tests, 32 days after simultaneous inoculation or preinoculation with B. berengeriana f. sp. piricola and Trichoderma spp., the incidence of infected apple shoots was reduced, respectively, by 65.3,76.4% and 62.5,76.4%, and the index of infection reduced by 36.9,38.9 and 40.7,44.4, The effect of inoculating B. berengeriana f. sp. piricola 3 days after the antagonists were inoculated was greater (81.4,88.8%) than simultaneous inoculation (72.2,77.8%). Re-isolation from inoculated apple shoots demonstrated that the pathogen had been suppressed by Trichoderma. The ability to re-isolate the pathogen from apple after co-inoculation and pre-inoculation with Trichoderma spp. was reduced by 27.0,42.3% and 22.2,47.1%, respectively. The biocontrol field trial suggested that the B. berengeriana f. sp. piricola canker on apple shoots and stems and rotting fruit had been efficiently controlled by the application of spore suspensions of T. harzianum T88 and T. atroviride T95. The efficacy of control by Trichoderma is thus similar to that of routine chemical control. [source] Effects of tebuconazole on morphology, structure, cell wall components and trichothecene production of Fusarium culmorum in vitroPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2001Zhensheng Kang Abstract The effects of tebuconazole, a systemic fungicide, on the morphology, structure, cell wall components and toxin production of Fusarium culmorum were investigated in vitro. Treatment was by application of four filter paper strips (0.75,cm,×,5.0,cm) soaked in 20,µg,ml,,1 fungicide placed around a point inoculum in Petri dishes. Mycelial growth was strongly inhibited by fungicide treatment. Scanning electron microscopic observations showed that the fungicide caused irregular swelling and excessive branching of hyphae. The morphological changes induced by the fungicide at the ultrastructural level included considerable thickening of the hyphal cell walls, excessive septation, the formation of the incomplete septa, extensive vacuolisation, accumulation of lipid bodies and progressing necrosis or degeneration of the hyphal cytoplasm. Non-membrane inclusion bodies were often detected in the hyphal cytoplasm. Furthermore, the formation of new hyphae (daughter hyphae) inside collapsed hyphal cells was common following treatment. The daughter hyphae also displayed severe alterations such as irregular thickening of the cell walls and necrosis of the cytoplasm. Using cytochemical techniques, the labelling densities of chitin and ,-1,3-glucan in the cell walls of the fungicide-treated hyphae were more pronounced than in those of the control hyphae. Moreover, immunogold labelling with antiserum against deoxynivalenol (DON) revealed that Fusarium toxin DON was localized in the cell walls, cytoplasm, mitochondria and vacuoles of the hyphae from the control and the fungicide treatment, but the labelling density in the fungicide-treated hyphae decreased dramatically compared with the control hyphae, indicating that tebuconazole reduced Fusarium toxin production of the fungus. © 2001 Society of Chemical Industry [source] | ||||||||||