We characterized 24 Japanese isolates of Magnaporthe grisea by DNA fingerprinting and electrophoretic karyotyping. These isolates included seven Japanese differential strains as well as field isolates belonging to various pathogenic races which were collected from all over Japan. We used previously cloned repetitive DNAs, MGR586 and pMG6015, as DNA fingerprinting probes. Bootstrapping analysis revealed that pMG6015 is effective for constructing a robust phylogenetic tree. Five clonal lineages were found in the phylogenetic analysis. All field isolates belonged to one particular clonal lineage JBLA-K04. Electrophoretic karyotypes were polymorphic among isolates in the lineage JBLA-K04, but some similarities of karyotype were observed in the isolates of similar pathogenic race. These results indicate that field isolates of M. grisea were derived from a limited number of clonal lineages and diverged in their host-cultivar specificity, and that variation at the chromosomal level is correlated to race differentiation in the clonal lineage JBLA-K04.
Cellulase induction by β-glucodisaccharides was investigated by using non-cellulase-induced mycelia of Penicillium purpurogenum P-26, a highly-cellulase-producing fungus. Gentiobiose induced significant amounts of cellulase compared with cellobiose when nojirimycin was added to the induction medium to inhibit extracellular β-glucosidase activity. Thiogentiobiose (6- S -β- d -glucopyranosyl-6-thio- d -glucose), a sulfur-containing analog of gentiobiose, was more effective for cellulase induction than gentiobiose even in the absence of nojirimycin. Thiogentiobiose appeared to be a gratuitous inducer since it was not metabolized during cellulase induction. Gentiobiose was formed from cellobiose by the intracellular β-glucosidase of P. purpurogenum. These findings indicate that gentiobiose is an active inducer of cellulase for this fungus and may possibly be formed by intracellular β-glucosidase from cellobiose.
A Gram-reaction-positive aerobic actinomycete, designated strain MN08-A0118(T), which produced short chains of non-motile spores on the tips of long sporophores and formed yellow-brown colonies with branched substrate mycelium, was studied in detail to determine its taxonomic position. On the basis of 16S rRNA gene sequence analyses, strain MN08-A0118(T) was grouped into the genus Herbidospora, being most closely related to Streptosporangium claviforme (98.2%), Herbidospora osyris (98.2%), Herbidospora daliensis (98.2%), Herbidospora cretacea (97.9%) and Herbidospora yilanensis (97.4%). Chemotaxonomic data supported allocation of the strain to the genus Herbidospora. MK-10(H(4)) was the predominant menaquinone with minor amounts of MK-10(H(6)), MK-10(H(2)) and MK-9(H(4)); the fatty acid profile contained major amounts of iso-C(16:0), C(17:0) 10-methyl, iso-C(14:0) and iso-C(16:0) 2-OH; the phospholipid profile contained phosphatidylethanolamine, phosphatidylmethylethanolamine and glucosamine-containing phospholipids; and the whole-cell sugars included ribose, glucose, galactose, madurose and rhamnose (trace). The phylogenetic data, phenotypic and genotypic properties and DNA-DNA hybridization differentiated this strain from its closely related strains, S. claviforme (35-54% DNA-DNA relatedness), H. osyris (39-51%), H. daliensis (3-16%), H. cretacea (34-39%) and H. yilanensis (34-42%). Thus, MN08-A0118(T) represents a novel species of the genus Herbidospora, for which the name Herbidospora mongoliensis sp. nov. is proposed, with MN08-A0118(T) ( = NBRC 105882(T) = VTCC D9-22(T)) as the type strain. In addition, DNA-DNA hybridization results showed that S. claviforme and H. osyris are synonyms of H. cretacea.
Two actinomycetes, designated MN08-A0270(T) and MN08-A0297(T), were isolated from soil from the area around Khuvsgul Lake, Khuvsgul province, Mongolia, and subjected to phenotypic and genotypic characterization. They produced well-developed, branched substrate hyphae and, similar to closely related species of the genus Pseudonocardia, produced zigzag-shaped aerial hyphae by acropetal budding and blastospores. A comparative analysis of 16S rRNA gene sequences indicated that strains MN08-A0270(T) and MN08-A0297(T) formed two distinct clades within the genus Pseudonocardia and were respectively most closely related to Pseudonocardia yunnanensis NBRC 15681(T) (97.3 % similarity) and Pseudonocardia thermophila IMSNU 20112(T) (97.1 %). Chemotaxonomic characteristics, including cell-wall diaminopimelic acid, whole-cell sugars, fatty acid components and major menaquinones, suggested that the two organisms belonged to the genus Pseudonocardia. Strains MN08-A0270(T) and MN08-A0297(T) could be differentiated from each other and from closely related species of the genus Pseudonocardia by physiological and biochemical characteristics, predominant fatty acids, menaquinones and whole-cell sugar components. Combined with the results of a broad range of phenotypic tests and DNA-DNA hybridization data and phylogenetic analysis, these results support the conclusion that these strains represent two novel species of the genus Pseudonocardia, for which we propose the names Pseudonocardia mongoliensis sp. nov. (type strain MN08-A0270(T) = NBRC 105885(T) = VTCC D9-25(T)) and Pseudonocardia khuvsgulensis sp. nov. (type strain MN08-A0297(T) = NBRC 105886(T) = VTCC D9-26(T)).
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