Search results for "Imperfect"
showing 10 items of 158 documents
Supression of Botrytis cinerea causing grey mould disease of grape vine (Vitis vinifera) and its pectinolytic activities by a soil bacterium
1997
Abstract Botrytis cinerea was found to be pathogenic to grapevine, producing characteristic grey mould symptoms within 7 days of inoculation into vitroplants. An endospore forming bacterial strain (GI 070), Bacillus circulans, was found to be antagonist against this disease causing fungus. Under laboratory conditions the bacterial culture or its filtrate brings about complete suppression of the fungus in Petri-dishes and the grey mould symptoms on grapevine vitroplants. Pectinolytic activities (Polygalacaturonase, Pectin lyases) of Botrytis cinerea were also influenced by these bacteria. Details of the fungal parasite, its biological control and its pectinolytic activities are discussed in …
Isotope Fractionation of Selenium During Fungal Biomethylation by Alternaria alternata
2011
The natural abundance of stable Se isotopes may reflect sources and formation conditions of methylated Se. We aimed at (1) quantifying the degree of methylation of selenate [Se(VI)] and (hydro)selenite [Se(IV)] by the fungus Alternaria alternata at pH 4 and 7 and (2) determining the effects of these different Se sources and pH values on 82Se/76Se ratios (δ82/76Se) in methylselenides. Alternaria alternata was incubated with Se(VI) and Se(IV) in closed microcosms for 11-15 days and additionally with Se(IV) for 3-5 days at 30 °C. We determined Se concentrations and δ82/76Se values in source Se(VI) and Se(IV), media, fungi, and trapped methylselenides. In Se(VI) incubations, methylselenide vola…
Lipid accumulation inTrichodermaspecies
1992
Two filamentous fungi, Trichoderma harzianum and Trichoderma viride, were compared for their ability to synthesize lipids on different carbon and nitrogen sources. Three culture media were selected for each strain after preliminary screening. All the test media were nitrogen-deficient (C/N = 60) so as to stimulate lipid accumulation. For both microorganisms the glucose-ammonium sulphate medium was the most conducive to lipid production: a lipid accumulation of 17% (w/w) of biomass dry weight was obtained for T. harzianum and of 32% (w/w) of biomass dry weight for T. viride. In sucrose-sodium nitrate medium T. harzianum was able to accumulate almost 25% (w/w) of its biomass in lipid form. Ho…
Wanted : pathogenesis-related marker molecules for Fusarium oxysporum
2003
Summary Although Fusarium oxysporum pathogens cause severe wilts in about 80 botanical species, the mechanisms of pathogenicity and symptom induction are poorly understood. Knowledge about the genetic and biochemical pathways involved in the pathogenesis of F. oxysporum would be invaluable in getting targets for both fungicide development and search for biocontrol agents. In this respect, we described the main approaches that have been developed to identify some mechanisms underlying the pathogenesis of F. oxysporum . During the last decades, the potential functions triggering of F. oysporum pathogenicity have mainly been investigated by comparing soilborne pathogenic strains with nonpathog…
Collagen overglycosylation: a biochemical feature that may contribute to bone quality.
2005
Skeletal ability to resist mechanical stress is determined by bone amount and quality, which relies on macro- and micro-architecture, turnover, bone matrix, and mineralisation; the role of collagen has not been clearly elucidated. Numerous post-translational steps are involved in collagen type I biosynthesis, including residue hydroxylation and glycosylation catalysed by enzymes that work until the protein folds forming the triple helix; therefore, folding rate regulates these processes. Overglycosylated hydroxylysines are poor substrates for epsilon-amino group deamination which initiates cross-link formation. Three clinical conditions associated with fractures may relate collagen overglyc…
Degradation of stilbene-type phytoalexins in relation to the pathogenicity of Botrytis cinerea to grapevines
1996
The ability of eight isolates of Botrytis cinerea to degrade the stilbene phytoalexins, resveratrol and pterostilbene, was compared with their pathogenicity to grapevines. All strains which degraded resveratrol and pterostilbene were highly or moderately pathogenic to in vitro cultures of grapevines (Vitis rupestris) after inoculation with agar disks containing mycelium, while those which were unable to degrade phytoalexins were non-pathogenic. In all cases, the hydroxystilbene-degrading activity was related to the presence of laccase activity in the culture filtrates, as shown by using syringaldazine as substrate. The role of laccase-mediated degradation of phytoalexins in relation to path…
Stilbene Content of MatureVitis viniferaBerries in Response to UV-C Elicitation
2001
A method using HPLC analysis has been used to compare the level of resveratrol and its derivatives, piceid, pterostilbene and epsilon-viniferin, in grapevine berries of three Vitis vinifera varieties. The concentration of these compounds has been evaluated in healthy and Botrytis cinerea infected grape clusters, both in natural vineyard conditions and in response to UV elicitation.
Quantitative separation of Trichoderma lipid classes on a bonded phase column.
1992
Bond Elut aminopropyl columns were used to purify the different lipid classes of Trichoderma harzianum and Trichoderma viride. This methodology permitted good separation of the fungal lipid classes in less time than traditional techniques. The incorporation of [1 (14)C]linoleic acid into neutral lipids, free fatty acids and phospholipids was quantified for both strains. The fatty acid profile of the different lipid classes of these fungal strains was determined as a function of culture time.
Changes in cell wall pectin and pectinase activity in apple and tomato fruits duringPenicillium expansum infection
2006
Cell wall pectin degradation in apple and tomato fruit during infection by Penicillium expansum was investigated. In infected apple fruit, a significant decrease in the average molecular mass was observed in pectins extracted with CDTA and also in pectins extracted with Na2CO3. In tomato fruits, depolymerisation was also observed in both pectic fractions during infection, the major change being in the pectins extracted with Na2CO3. This pectin depolymerisation associated with P. expansum infection can be attributed to the action of pectinases; in apple fruit, a significant increase in polygalacturonase and pectin methylesterase was observed in infected fruits, although in tomato fruit the o…
Isolation and identification of roseotoxin S from cultures of the fungus Trichothecium roseum
1988
The structure of reseotoxin S, a new cyclodepsipeptide of the fungus Trichothecium roseum, is described. It consists of three amino acids and two hydroxy acids. Besides the structure, possibilities of proof and isolation as well as analytical data are given.