The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Dietmar Haltrich - One of the best experts on this subject based on the ideXlab platform.
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purification and characterization of cellobiose dehydrogenase from the plant pathogen sclerotium Athelia rolfsii
Applied and Environmental Microbiology, 2001Co-Authors: Ursula Baminger, Sai S Subramaniam, V Renganathan, Dietmar HaltrichAbstract:Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoenzyme produced by several wood-degrading fungi. In the presence of a suitable electron acceptor, e.g., 2,6-dichloro-indophenol (DCIP), cytochrome c, or metal ions, CDH oxidizes cellobiose to cellobionolactone. The phytopathogenic fungus Sclerotium rolfsii (teleomorph: Athelia rolfsii) strain CBS 191.62 produces remarkably high levels of CDH activity when grown on a cellulose-containing medium. Of the 7,500 U of extracellular enzyme activity formed per liter, less than 10% can be attributed to the proteolytic product cellobiose:quinone oxidoreductase. As with CDH from wood-rotting fungi, the intact, monomeric enzyme from S. rolfsii contains one heme b and one flavin adenine dinucleotide cofactor per molecule. It has a molecular size of 101 kDa, of which 15% is glycosylation, and a pI value of 4.2. The preferred substrates are cellobiose and cellooligosaccharides; additionally, β-lactose, thiocellobiose, and xylobiose are efficiently oxidized. Cytochrome c (equine) and the azino-di-(3-ethyl-benzthiazolin-6-sulfonic acid) cation radical were the best electron acceptors, while DCIP, 1,4-benzoquinone, phenothiazine dyes such as methylene blue, phenoxazine dyes such as Meldola's blue, and ferricyanide were also excellent acceptors. In addition, electrons can be transferred to oxygen. Limited in vitro proteolysis with papain resulted in the formation of several protein fragments that are active with DCIP but not with cytochrome c. Such a flavin-containing fragment, with a mass of 75 kDa and a pI of 5.1 and lacking the heme domain, was isolated and partially characterized.
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purification and some properties of a thermostable acidic endo β 1 4 d mannanase from sclerotium Athelia rolfsii
Fems Microbiology Letters, 1999Co-Authors: Alois Sachslehner, Dietmar HaltrichAbstract:Abstract The phytopathogenic fungus Sclerotium ( Athelia ) rolfsii forms one major endo-β-1,4- D -mannanase (EC 3.2.1.78) under non-induced and derepressed conditions, i.e. after depletion of glucose which was used as the only carbohydrate substrate for its cultivation. This mannanase was purified to electrophoretic homogeneity by ammonium sulfate precipitation, hydrophobic interaction chromatography, anion exchange chromatography and gel filtration. The enzyme is a glycoprotein with a molecular mass of 46.5±2 kDa (SDS-PAGE), an isoelectric point of 2.75, and a pH optimum of 3.0–3.5. The enzyme is especially stable in the acidic region with an exceptional half-life of activity of 41 days at pH 4.5 and 50°C. It exerts activity on β-1,4-mannan from ivory nut, which is hydrolyzed mainly to mannobiose and mannotriose, as well as on glucomannan, galactomannan, galactoglucomannan, and mannooligosaccharides not smaller than mannotetraose. The main end-products mannotriose and to a lesser extent mannobiose inhibit its activity moderately.
Zamir K Punja - One of the best experts on this subject based on the ideXlab platform.
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genetic diversity among mycelial compatibility groups of sclerotium rolfsii teleomorph Athelia rolfsii and s delphinii
Fungal Biology, 2001Co-Authors: Zamir K PunjaAbstract:The genetic relationships among 132 isolates of Sclerotium rolfsii (teleomorph Athelia rolfsii ) collected during 1967–97 from 36 different host species over a wide geographic range representing 13 countries were investigated using mycelial compatibility groupings and RAPD analysis. A smaller group of 15 Sclerotium delphinii isolates from five host species and a limited geographic distribution was also studied. The development of aversion reactions following mycelial pairings of isolates in all possible combinations on potato dextrose agar was used to differentiate 71 mycelial compatibility groups (MCG) in S. rolfsii and five MCG in S. delphinii. Many MCG were unique single-member groups and these generally were found in widely separated geographic regions or countries. There was no clear relationship between host of origin and MCG, except for a majority of isolates of S. rolfsii from turfgrass that belonged to MCG 1. Within a specific geographic region, e.g. California, there usually were several different MCG present, some of which were recovered from the same host species. In addition, specific MCG of S. rolfsii were recovered from widely separated geographic regions as well as different host species, e.g. MCG 1 was recovered from turfgrass, carrot, tobacco, and tomato in California, Georgia, North Carolina, and Mexico, respectively. The extent of genetic diversity within and among MCG of S. rolfsii and S. delphinii was studied using RAPD analysis. Isolates from different MCG could be differentiated by their unique banding patterns using six primers. There were no discernible relationships among the various MCG using UPGMA analysis. Isolates within a particular MCG were also genetically diverse, but shared greater numbers of common bands and clustered together. Only a few members of some MCG in S. rolfsii and S. delphinii that had identical RAPD patterns were considered to be clonally derived. The extent of genetic diversity among isolates of S. delphinii was lower than that observed in S. rolfsii.
Dinesh Kumar - One of the best experts on this subject based on the ideXlab platform.
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draft whole genome sequence of groundnut stem rot fungus Athelia rolfsii revealing genetic architect of its pathogenicity and virulence
Scientific Reports, 2017Co-Authors: M A Iquebal, Rukam S Tomar, Manoj V Parakhia, Deepak Singla, Sarika Jaiswal, Visha M Rathod, S M Padhiyar, Neeraj Kumar, Anil Rai, Dinesh KumarAbstract:Groundnut (Arachis hypogaea L.) is an important oil seed crop having major biotic constraint in production due to stem rot disease caused by fungus, Athelia rolfsii causing 25–80% loss in productivity. As chemical and biological combating strategies of this fungus are not very effective, thus genome sequencing can reveal virulence and pathogenicity related genes for better understanding of the host-parasite interaction. We report draft assembly of Athelia rolfsii genome of ~73 Mb having 8919 contigs. Annotation analysis revealed 16830 genes which are involved in fungicide resistance, virulence and pathogenicity along with putative effector and lethal genes. Secretome analysis revealed CAZY genes representing 1085 enzymatic genes, glycoside hydrolases, carbohydrate esterases, carbohydrate-binding modules, auxillary activities, glycosyl transferases and polysaccharide lyases. Repeat analysis revealed 11171 SSRs, LTR, GYPSY and COPIA elements. Comparative analysis with other existing ascomycotina genome predicted conserved domain family of WD40, CYP450, Pkinase and ABC transporter revealing insight of evolution of pathogenicity and virulence. This study would help in understanding pathogenicity and virulence at molecular level and development of new combating strategies. Such approach is imperative in endeavour of genome based solution in stem rot disease management leading to better productivity of groundnut crop in tropical region of world.
Naoyuki Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic relationship of sclerotium rolfsii teleomorph Athelia rolfsii and s delphinii based on its sequences
Fungal Biology, 2003Co-Authors: Ikuko Okabe, Naoyuki MatsumotoAbstract:The phylogenetic relationships of the stem rot pathogens Sclerotium rolfsii and S. delphinii were examined, based on their rDNA ITS sequences. The ITS regions were cloned and sequenced to identify three distinct ITS types: r-1, r-2, and r-3. Two different ITS types exist within S. rolfsii and S. delphinii strains. Japanese strains and one strain of S. rolfsii from the USA contain types r-1 and r-2, whereas another strain from the USA and one from Chile have only one ITS type, r-2. S. delphinii strains have types r-1 and r-3. We discuss the implications of the common presence of ITS type r-1 for the taxonomy and evolution of this species complex.
C E Harlton - One of the best experts on this subject based on the ideXlab platform.
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genetic diversity in slerotium Athelia rolfsii and related species
Phytopathology, 1995Co-Authors: C E HarltonAbstract:Pairings among 119 isolates of Sclerotium rolfsii, 11 of S. delphinii, and two of S. coffeicola on potato-dextrose agar to establish mycelial compatibility groups (MCGs) revealed 49, 3, and 2 MCGs, respectively, in a worldwide collection. Within an MCG, isolates were often from the same host and geographical area ; however, widely diverse isolates also were grouped within the same MCG. The host of origin of the isolate was not correlated with the MCG except in S. delphinii. Many MCGs were comprised of only one isolate. Variation in nuclear rDNA [internal transcribed spacer (ITS) regions] was examined following restriction enzyme digests. Restriction fragment length polymorphisms (RFLPs) were obtained with AluI, HpaII, RsaI, and MboI and could distinguish amongst the three Sclerotium spp. and three Athelia spp. (an outgroup). Combined banding patterns for the four enzymes were used to characterize intraspecific variation in the three Sclerotium spp. There were 12 subspecific groupings in S. rolfsii, one in S. delphinii, and two in S. coffeicola; some of these groupings correlated with their MCG. However, isolates within an MCG could show different ITS-RFLP patterns and certain patterns were also dispersed among different MCGs. The total sum of digested fragment sizes exceeded the undigested polymerase chain reaction product in several S. rolfsii isolates. This length discrepancy was not due to artifacts or incomplete digestion and, therefore, must have resulted from variation among rDNA copies in the presence of restriction sites. Furthermore, segregation of two MboI restriction patterns in the ITS region among 29 single-basidiospore strains, derived from four parental field isolates of S. rolfsii with one pattern, suggested the presence of two distinct rDNA types in the field isolates. The rDNA types may reflect a heterokaryotic nuclear condition in field isolates of S. rolfsii. Restriction maps and phylogenetic analyses supported a close affinity of the three Sclerotium spp., which may be more appropriately designated as subspecific varieties of S. rolfsii.