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E. Benade - One of the best experts on this subject based on the ideXlab platform.
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Conidium development in Sporothrix anamorphs of Ophiostoma
Fungal Biology, 1997Co-Authors: E. BenadeAbstract:Hyalorhinocladiella and Sporothrix are two common mycelial anamorphs of Ophiostoma that are difficult to distinguish from each other. Sporothrix spp. differ visibly from Hyalorhinocladiella by the presence of denticles on the conidiogenous cells. Graphium and Sporothrix are often synanamorphs of the same Ophiostoma species and the aim of this study was to determine whether a relationship exists between sympodial Conidium development in Sporothrix and annellidic development in Graphium. Conidium development was examined in Sporothrix schenckii, Ophiostoma nigrocarpum and Ophiostoma piceae. Using fluorescence microscopy, as well as scanning and transmission electron microscopy, distinct denticles were observed on the conidiogenous cells in Sporothrix spp. In some cases, these conidiogenous cells were reduced, giving them a Hyalorhinocladiella-like appearance. Results of this study suggest that a continuum in patterns of Conidium development exists between Sporothrix, Hyalorhinocladiella and Graphium. The linear extent, and the angle of the proliferation stage with reference to the long axis of the conidiogenous cell, appear to determine the form of Conidium development.
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Conidium development in the Hyalorhinocladiella anamorphs of Ceratocystiopsis minuta-bicolor and Ophiostoma minus
Botany, 1996Co-Authors: E. BenadeAbstract:The genus Hyalorhinocladiella was characterized by its simple conidiophores with conidiogenous cells that proliferate sympodially. However, recent studies revealed that the Hyalorhinocladiella anamorph of Ophiostoma ips has annellidic Conidium development. The aim of this study was to determine whether other species in the genus share this characteristic. Conidium development was examined in the type species, Hyalorhinocladiella minuta-bicolor, and in the Hyalorhinocladiella anamorph of Ophiostoma minus. Light and fluorescence microscopy indicated that conidia developed by sympodial proliferation. In contrast, scanning and transmission electron microscopy revealed distinct annellations on the conidiogenous cells. Conidium development in Hyalorhinocladiella is therefore annellidic, and the appearance of sympodial development results from displacement of the long axis of the conidiogenous cell through percurrent proliferation. The circumscription of the genus Hyalorhinocladiella is therefore revised to incl...
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Conidium DEVELOPMENT IN THE HYALORHINOCLADIELLA ANAMORPH OF OPHIOSTOMA IPS
Mycologia, 1995Co-Authors: E. Benade, M.j. Wingfield, P. S. Van WykAbstract:The anamorph of aphioslama iPs has been suggested to have both sympodial and phialidic co- nidium development. The phialidic form has conse- quently been referred to as Acremonium-like and the sympodial form as a species of Hyalorhinocladiella. The aim of this study was to determine the mode of co- nidium development and consequently the identity of the anamorph of aphiosloma iPs. Light microscopy clearly indicated that sympodial proliferation oc- curred during conidiogcnesis. However, using scan- ning electron microscopy, conidiogenous cells were found to be annellidic. This was confirmed using trans- mission electron microscopy where distinct anneIJa- tions could be distinguished on conidiogenous cells. \\le conclude that Conidium development in the ana-
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Conidium development in Ceratocystis autographa
Mycological Research, 1995Co-Authors: M.j. Wingfield, E. Benade, P. S. Van Wyk, C. VisserAbstract:Ceratocystis s.l. includes Ceratocystis s.s., Ophiostoma and Ceratocystiopsis . These genera are distinguished by their anamorphs, ascospore morphology and sensitivity to cycloheximide. Ceratocystis autographa is unusual in that it reportedly has both Ophiostoma and Ceratocystis anamorphs. The aim of this study was to clarify confusion relating to the anamorphs of C. autographa and thus its generic placement. Light and scanning electron microscopy confirmed the presence of two distinct anamorphs in the fungus. One was Sporothrix -like and very rare while the other was Chalara -like. Light and fluorescence microscopy, as well as scanning (SEM) and transmission (TEM) electron microscopy of the Chalara -like anamorph revealed cylindrical conidia with only a basal delimiting septum. TEM of this state showed vesicles at the apex of the conidiogenous cell, indicating apical wall building. This differs from other species of Chalara where conidia have apical and basal delimiting septa and develop through ring wall building. Furthermore, C. autographa was tolerant to cycloheximide and is, therefore, more closely related to Ophiostoma than Ceratiocystis . Results of this study suggest that the Chalara -like anamorph belongs to a genus other than Chalara and is a probable result of convergent evolution in a fungus adapted to insect dispersal.
Charles W. Mims - One of the best experts on this subject based on the ideXlab platform.
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ultrastructure of sporodochium and Conidium development in the anamorphic fungus epicoccum nigrum
Botany, 2005Co-Authors: Charles W. Mims, Elizabeth A RichardsonAbstract:Scanning and transmission electron microscopy were used to examine sporodochium and Conidium development in Epicoccum nigrum Link. Each sporodochium, a slightly raised mass of hyphae consisting of ...
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ultrastructure of sporodochium and Conidium development in the anamorphic fungus epicoccum nigrum
Botany, 2005Co-Authors: Charles W. Mims, Elizabeth A RichardsonAbstract:Scanning and transmission electron microscopy were used to examine sporodochium and Conidium development in Epicoccum nigrum Link. Each sporodochium, a slightly raised mass of hyphae consisting of a pseudoparenchymous stroma covered with muriform conidia, arose from a group of loosely packed hyphae that formed on the agar surface. Conidiophores developed from the surface of the stroma. Each possessed a two-layered wall consisting of an inner electron transparent layer and an outer electron dense layer. Most conidiophores consisted of only two cells, the apical of which became swollen and gave rise to a solitary Conidium initial in a holoblastic fashion. This initial enlarged and became divided into a smaller basal cell and a larger apical cell by a transverse septum. While the basal cell did not divide further, the apical cell became divided into numerous cells as the result of the formation of longitudinal and transverse septa. As a Conidium matured the electron transparent inner layer of its wall thicke...
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ultrastructure of conidia and Conidium germination in the plant pathogenic fungus alternaria cassiae
Botany, 1997Co-Authors: Charles W. Mims, M A Rogers, C G Van DykeAbstract:Transmission electron microscopy of plunge-frozen and freeze-substituted samples was used to examine germinating conidia of Alternaria cassiae, a plant pathogenic fungus used as a biological control agent for sicklepod (Cassia obtusifolia). Hydrated conidia on small pieces of dialysis membrane were incubated for 1, 2, or 3 h on the surface of corn meal agar prior to fixation. Conidia were large, darkly pigmented, and surrounded by a thick, two-layered wall. Each Conidium was divided by transverse and longitudinal septa into multiple cells, a few of which sometimes appeared necrotic. Each septum tapered to a small central pore region with which Woronin bodies were associated. Each healthy cell of a Conidium contained a typical complement of cellular organelles including multiple nuclei. With the exception of lipid bodies, all the various organelles were well preserved by plunge freezing and freeze substitution. Evidence of germ tube development was visible by 2 h post-incubation and well-developed germ tub...
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Ultrastructure of the ungerminated Conidium of Blumeria graminis f.sp. hordei
Canadian Journal of Botany, 1996Co-Authors: Donald R. Roberts, Charles W. Mims, Melvin S. FullerAbstract:Ungerminated conidia of Blumeria graminis f.sp. hordei were prepared for transmission electron microscopy using cryofixation and freeze-substitution. Conidia were uninucleate, with the nucleus located in the central portion of the Conidium, typically off to one side. The nucleus was spherical and contained a distinct nucleolus with an associated satellite. Conidia contained numerous large, spherical vacuoles that occupied much of the spore volume. Vacuolar contents were mostly homogeneous with occasional electron-opaque inclusions. Much of the cytoplasm consisted of lightly staining aggregations of glycoprotein that could be labelled with Concanavalin A – gold and that stained darkly using a modified Thiery's reaction specific for carbohydrates containing vicinal hydroxyl groups. Mitochondria, strands of endoplasmic reticulum, Golgi body equivalents, multivesicular bodies, microbodies, Woronin bodies, and microtubules were present in the Conidium. Cuboidal, stacked, electron-translucent structures also we...
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ultrastructure of conidia Conidium germination and appressorium development in the plant pathogenic fungus colletotrichum truncatum
Botany, 1991Co-Authors: Gerald C Van Dyke, Charles W. MimsAbstract:Nongerminating conidia of Colletotrichum truncatum were coated with copious amounts of a finely fibrillar extracellular matrix. This matrix spread out onto the dialysis membrane used as a substrate in this study. Each thin-walled Conidium contained a single nucleus that underwent mitosis 1–2 h following placement of aqueous suspensions of conidia on membranes. A septum subsequently developed near the middle of the Conidium, creating two uninucleate cells. Just prior to or during septum development a germ tube emerged laterally, usually near one end of the Conidium. The nucleus moved into the germ tube and underwent mitosis. One daughter nucleus remained in the germ tube, the other moved back into the Conidium. Developing germ tubes appeared to produce large amounts of electron-dense, fibrillar material that coated their surfaces. This material blended into the remnants of the matrix initially coating conidia and could not be clearly differentiated from the latter material. Germ tubes grew to various lengt...
Richard E. Falloon - One of the best experts on this subject based on the ideXlab platform.
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nutrient amendments affect trichoderma atroviride Conidium production germination and bioactivity
Biological Control, 2016Co-Authors: Amir Daryaei, Travis R. Glare, Richard E. Falloon, E E JonesAbstract:Abstract Trichoderma atroviride LU132, the active organism in two commercialised biological control products, was grown under different in vitro culture carbon to nitrogen ratios, to assess effects on Conidium production, germination and bioactivity. Sucrose as a carbon source in agar-based growth media was adjusted to 4.2, 8.4, or 16.8 g/l carbon, and soy peptone as a nitrogen source to 0.03, 0.05, 0.11, 0.21, 0.42, 0.84, 1.68, or 3.36 g/l, to give C:N ratios in the growth media ranging from 5:1 to 160:1. Conidium production was greatest at 16.8 g/l carbon and least at 4.2 g/l, and was prolific at C:N 5:1, but was sparse at C:N 160:1. Mean Conidium germination was greatest (68%) at 4.2 g/l carbon and least (58%) at 16.8 g/l carbon. Germination was greatest (74%) for C:N 5:1 and least (52%) for C:N 160:1. Trichoderma inhibition activity against the diseases-causing Rhizoctonia solani was also affected slightly for colonies obtained from conidia grown on media with 4.2 g/l carbon from 67% to 70% with 16.8 g/l carbon. Inhibition activity was greatest (73%) from conidia produced at C:N 5:1 and least (63%) from C:N 160:1. Low amounts of carbohydrate in growth media at C:N ratios near 5:1 were optimum for growth of T. atroviride LU132. Large amounts of carbohydrate probably repressed carbon catabolism, resulting in decreased Conidium fitness. These results provide new knowledge to assist commercial production of biocontrol agents based on T. atroviride LU132.
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ph and water activity in culture media affect biological control activity of trichoderma atroviride against rhizoctonia solani
Biological Control, 2016Co-Authors: Amir Daryaei, Travis R. Glare, Richard E. Falloon, E E JonesAbstract:Abstract Biological control activity of Trichoderma spp. is heavily influenced by abiotic factors. Effects of pH and water activity (aw) in culture media of Trichoderma atroviride LU132 were assessed on Conidium production, germination percentage and bioactivity against a soil-borne pathogen Rhizoctonia solani in dual agar culture assays. The effects of pH and buffer capacity in media were tested on T. atroviride colonies using different proportions (50, 100, 200 and 400 mM) of phosphate buffers at pHs of 3.5, 4.5, 5.5, 6.5, 7.5 or 8.5. Water activity experiments tested different aw values (0.998, 0.995, 0.985, 0.977, 0.961 and 0.948). Conidium production was reduced with increasing phosphate buffer concentrations from 50 to 400 mM. Maximum germination, and inhibition activity against R. solani was measured for conidia obtained from medium at pH 7.5. Greatest Conidium production occurred at aw 0.995 and the least at aw 0.948. Mean Conidium germination was greatest (78%) from media at aw 0.961, and least (21%) from aw 0.985. Inhibition and overgrowth activities of Trichoderma colonies were greatest at aw 0.961 and least at aw 0.998. This study has demonstrated that manipulation of culture conditions as such may improve Conidium fitness (quantity and quality). However, these factors may not have caused independently effects on the fungus. Effects of physical growth conditions (besides nutritional requirements) are likely to be important for optimum production of biocontrol agents based on T. atroviride LU132, and other similar biocontrol agents.
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Biochemical characteristics of Trichoderma atroviride associated with Conidium fitness for biological control
Biocontrol Science and Technology, 2015Co-Authors: Amir Daryaei, E. Eirian Jones, Travis R. Glare, Hossein Alizadeh, Richard E. FalloonAbstract:ABSTRACTEffects of abiotic factors during production (temperature, nutrients, water activity, pH) on Conidium fitness (quantity and quality) of Trichoderma atroviride LU132 (a key biocontrol agent) were studied. Conidia from the culturing regimes which resulted in greatest and least bioactivity against Rhizoctonia solani in dual culture assays were selected to assess effects of storage conditions on conidial fitness over time. Further studies assessed interaction effects of temperatures (20°C or 30°C) and sugars (dextrose or sucrose) on Conidium germination and bioactivity as fresh conidia, or after 6 months of storage. Biochemical analyses of sugars and fatty acids were carried out to determine relationships between quality variations and cellular characteristics for conidia produced in different culturing conditions. Low trehalose content in conidia (e.g. at 20°C) was associated with the least Conidium fitness, although high trehalose content did not necessarily support Conidium fitness. High proportion...
Steven N. Jeffers - One of the best experts on this subject based on the ideXlab platform.
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Vegetative growth and Conidium production by Monilinia oxycocci in vitro
Mycologia, 2019Co-Authors: Peter G. Sanderson, Steven N. JeffersAbstract:The effects of various natural agar media, light, and temperature on mycelium growth of and Conidium production by Monilinia oxycocci were ex- amined in the laboratory under controlled condi- tions. Vegetative growth and sporulation were affect- ed differentially by these factors. Optimum vegetative growth and formation of stromata occurred on po- tato dextrose agar at 20-24 C in the dark. The min- imum and maximum temperatures for mycelium growth were 4 and 32 C, respectively. Production of conidia was best on V8 juice agar. The greatest num- bers of conidia were produced at 16 C, but abundant Conidium production was most consistent at 20 C. The influence of light on sporulation was inconsis- tent among trials and differed among media and iso- lates. However, on V8 juice agar at 20 C, production of conidia was most abundant in the dark. In general, considerable variability occurred with M. oxycocci throughout the study-among replicates of individ- ual isolates, among isolates within a trial, and among trials with the same isolates. The highly variable na- ture of M. oxycocci in vitro appears to be an inherent characteristic of this plant pathogenic fungus.
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Resistance to Benzimidazole and Dicarboximide Fungicides in Greenhouse Isolates of Botrytis cinerea
Plant Disease, 1999Co-Authors: L. F. Yourman, Steven N. JeffersAbstract:ABSTRACT In 1996 and 1997, 325 isolates of Botrytis cinerea were collected from 35 commercial greenhouses growing ornamental crops in South Carolina to determine the incidence of resistance to benzimidazole and dicarboximide fungicides. Conidium germination was assessed on a defined agar medium amended with either thiophanate-methyl (a benzimidazole) or vinclozolin (a di-carboximide). A total of 53 representative isolates were evaluated further for Conidium germination and mycelium growth on fungicide-amended medium and for infection of geranium seedlings treated with thiophanate-methyl or vinclozolin at label rates. Isolates were considered sensitive to thiophanate-methyl or vinclozolin when the effective concentration of the fungicide active ingredient resulting in 50% inhibition of germination (EC50-germ) was ≤5 μg/ml or when the effective concentration of fungicide active ingredient resulting in 50% inhibition of mycelium growth (EC50-growth) was ≤1 μg/ml. Of all isolates, 81% (262/325) were resistant...
Yulin Wang - One of the best experts on this subject based on the ideXlab platform.
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the sch9 kinase regulates Conidium size stress responses and pathogenesis in fusarium graminearum
PLOS ONE, 2014Co-Authors: Daipeng Chen, Yang Wang, Xiaoying Zhou, Yulin WangAbstract:Fusarium head blight caused by Fusarium graminearum is an important disease of wheat and barley worldwide. In a previous study on functional characterization of the F. graminearum kinome, one protein kinase gene important for virulence is orthologous to SCH9 that is functionally related to the cAMP-PKA and TOR pathways in the budding yeast. In this study, we further characterized the functions of FgSCH9 in F. graminearum and its ortholog in Magnaporthe oryzae. The ΔFgsch9 mutant was slightly reduced in growth rate but significantly reduced in conidiation, DON production, and virulence on wheat heads and corn silks. It had increased tolerance to elevated temperatures but became hypersensitive to oxidative, hyperosmotic, cell wall, and membrane stresses. The ΔFgsch9 deletion also had Conidium morphology defects and produced smaller conidia. These results suggest that FgSCH9 is important for stress responses, DON production, conidiogenesis, and pathogenesis in F. graminearum. In the rice blast fungus Magnaporthe oryzae, the ΔMosch9 mutant also was defective in conidiogenesis and pathogenesis. Interestingly, it also produced smaller conidia and appressoria. Taken together, our data indicate that the SCH9 kinase gene may have a conserved role in regulating Conidium size and plant infection in phytopathogenic ascomycetes.