Shigeyuki Murakami

Occurrence of Pseudomonas tolaasii on fruiting bodies of Lentinula edodes formed on Quercus logs

A bacterial disease occurred on fruiting bodies ofLentinula edodes that formed outdoors onQuercus bedlogs during winter. The pathogen was identified asPseudomonas tolaasii based on morphological and bacteriological characteristics. Symptoms exhibited by infected fruiting bodies ranged from mild browning to severe necrotic cavities that characteristically developed in the cap tissue along the periphery of the attachment area to the stalk. The mode of symptom development was greatly influenced by the internal tissue structure of fruiting bodies. Multiplication of bacterial cells within the fruiting bodies was strictly intercellular and thus differed from previously reported bacterial disease ofL. edodes incited by an unidentified rod-shaped bacterium. The present strain ofP. tolaasii was capable of attacking theL. edodes mycelium in the inner bark and outer sapwood regions and caused lysis of heavily infected hyphae.

Cytology and genetics of a sporeless mutant of Lentinus edodes

A sporulation-deficient (sporeless) mutant in Lentinus edodes gave rise to basidiocarps visibly indistinguishable from those of wild-type dikaryons. In the basidia, karyogamy and meiosis occurred n...

Endoconidium development and release in the hyphomycete Phaeotheca fissurella

On agar culture media, conidia of Phaeotheca fissurella did not germinate but enlarged to form small mother cells within four da. Division of the small mother cells occurred by development of multilayered, simple septa to form two to several daughter cells. Schizolysis ofthe cross walls resulted in separation ofthe daughter cells to form endoconidia which were subsequently released by rupture ofthe mother cell wall. After a 2-3-week incubation, colonies were elevated and consisted of numerous sclerotic cells. Active endosporulation was restricted to one to several cell layers from the exposed surface of these colonies where large mother cells containing many endoconidia were abundant. Release ofthe endoconidia from the larger mother cells often was by dissolution ofthe mother cell wall. The liberated endoconidia were uninucleate and contained well-defined mitochondria, ER, ribosomes, lipid bodies and vac? uoles.

Hymenophore development and evolution in Lentinus

Morphological evolution of the Lentinus hymenophore was investigated through scanning electron microscopic observations of development in cultured sporocarps of Lentinus tigrinus, L. crinitus, L. s...

Construction of a Genetic Linkage Map Based on Amplified Fragment Length Polymorphism Markers and Development of Sequence-Tagged Site Markers for Marker-Assisted Selection of the Sporeless Trait in the Oyster Mushroom (Pleurotus eryngii)

ABSTRACT A large number of spores from fruiting bodies can lead to allergic reactions and other problems during the cultivation of edible mushrooms, including Pleurotus eryngii (DC.) Quél. A cultivar harboring a sporulation-deficient (sporeless) mutation would be useful for preventing these problems, but traditional breeding requires extensive time and labor. In this study, using a sporeless P. eryngii strain, we constructed a genetic linkage map to introduce a molecular breeding program like marker-assisted selection. Based on the segregation of 294 amplified fragment length polymorphism markers, two mating type factors, and the sporeless trait, the linkage map consisted of 11 linkage groups with a total length of 837.2 centimorgans (cM). The gene region responsible for the sporeless trait was located in linkage group IX with 32 amplified fragment length polymorphism markers and the B mating type factor. We also identified eight markers closely linked (within 1.2 cM) to the sporeless locus using bulked-segregant analysis-based amplified fragment length polymorphism. One such amplified fragment length polymorphism marker was converted into two sequence-tagged site markers, SD488-I and SD488-II. Using 14 wild isolates, sequence-tagged site analysis indicated the potential usefulness of the combination of two sequence-tagged site markers in cross-breeding of the sporeless strain. It also suggested that a map constructed for P. eryngii has adequate accuracy for marker-assisted selection.

Postmeiotic nuclear behavior in Lentinus, Panus, and Neolentinus

We investigated nuclear behavior during basidiosporogenesis in Lentinw, Panus, and Neolentinus in an attempt to discover characters for taxonomic segregation of lentinoid-pleurotoid fungi. In Lentinus tigrinus and Panus lecomtei somatic hyphae are binucleate. Karyogamy and meiosis occur in the basidia, meiotic products migrate into spores and postmeiotic mitosis occurs; this is followed by back-migration of one nucleus from each spore into the basidium. Mature spores are consequently uninucleate and discharged basidia are quadrinucleate. In Neolentinus lepideus many somatic cells are multinucleate. Karyogamy, meiosis, and postmeiotic mitosis occur as in L. tigrinus and P. lecomtei, but there is no backmigration, mature spores are binucleate, and discharged basidia are anucleate. The patterns of nuclear behavior in L. tigrinus and P. lecomtei correspond to type C nuclear behavior as defined by Duncan and Galbraith, whereas that of Neolentinus corresponds to type D nuclear behavior. Lentinus and Panus cannot be distinguished on the basis of postmeiotic nuclear behavior, but both can be distinguished from Pleurotus which has been reported to have type A nuclear behavior sensu Duncan and Galbraith.

Isolation of the B incompatibility factor mutants in Pleurotus ostreatus

Abstract B incompatibility factor mutants (Bmut) in Pleurotus ostreatus were recovered from common-B mating heterokaryons resulted from matings between wild-type monokaryons with different A but the same B factors (A1B2 and A2B2) after NTG mutagenesis. The mutant monokaryons such as A1B2mut and A2B2mut were observed to have regularly uninucleated hyphal cells and to be compatible with each other. Matings between A1B2mut and A2B2mut monokaryons produced stable heterokaryons (A1B2mut + A2B2mut) that had binucleated hyphal cells with true clamp connections and formed normal fruit-bodies. Mating tests using basidiospore progeny from each of these heterokaryons revealed the bipolar mating pattern. Genetic analysis suggested that the mutation of B factor in P. ostreatus might occur in the B incompatibility factor genes.

Black spot disease of Lentinula edodes caused by the Hyphozyma synanamorph of Eleutheromyces subulatus

The Hyphozyma synanamorph of Eleuther- omyces subulatus was found to be the cause of black spot disease of Lentinula edodes fruiting bodies. Mul- tiplication of yeastlike cells and hyphae of Hyphozyma resulted in blackening and mild lysis of the infected host cap tissues where partially degraded skeletal mi- crofibrils of host cell walls were abundant. In general, host tissue lysis remained superficial; however in some cases, Hyphozyma caused severe lysis and formed deep cavities containing remnants of highly dissolved host cell walls and numerous yeastlike cells of the pathogen. Enzyme assays demonstrated the ability of Hyphozyma to produce both chitinase and (3-(1,3) glucanase enzymes, requirements for hyphal wall degradation. On agar, conidiogenesis is enter- oblastic in the Hyphozyma morph, whereas it is ap- parently holoblastic in the Eleutheromyces morph. No evidence of phialidic conidiogenesis was obtained.