ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026074

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTUltrastructural aspects of development of hat-shaped ascospores and centrum organization inO. cucullatumwere studied and compared with other species inCeratocystis sensu latoapparently having similar ascospores. The ascospore wall consisted of a reniform primary and ornamented secondary wall. Secondary wall ornamentation incorporated three equally spaced and parallel ridges along the length of the ascospore that gave the ascospore a triangular outline in transverse section. Brim appendages developed on the secondary wall at the rounded ends of the primary wall resulting in the hat-shaped appearance of the ascospores in side view. These appendages differed considerably from those of the symmetrically shaped and hemispherical bowler-hat ascospores previously observed inC. moniliformisandC. fimbriata.Centrum organization inO. cucullatumwas, however, similar to that previously illustrated ofO. davidsonii.In both of the latter species, young asci were arranged in a cluster at the ascomatal base. This was different to that inC. moniliformiswhere young asci lined the inner ascomatal wall.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026075

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTSeed of pearl millet,Pennisetum typhoides, prosomillet,Panicum miliaceum; and foxtail millet,Setaria italicawere collected from Nigeria, Lesotho, and Zimbabwe. The samples were collected from grain sold in markets, left unharvested in the field, stored in homes or grown on experimental farms. The most prevalentFusariumspecies recovered wereF. equiseti(34%),F. nygamai(26%),F. moniliforme(24%),F. semitectum(10%), andF. chlamydosporum(4%). OtherFusariumspecies isolated includedF. napiforme, F. subglutinans, F. graminearum, F. oxysporum, andF. solani; these species accounted for 3% of those recovered.Fusarium nygamaiandF. moniliformewere most frequently recovered from seed from Nigeria, whileF. equisetiandF. semitectumwere most prevalent in samples from Zimbabwe, andF. equisetiwas the only species isolated from samples from Lesotho.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026076

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTThe family Radiomycetaceae, which includes two genera,HesseltinellaandRadiomyces, is based, in part, on the production of a unique sporangiolum-bearing structure consisting of a once-septate stalk terminated by a vesicle bearing one or many uni- or multispored sporangiola. Zygospores, where known, have in common a smooth zygosporangial wall and opposed, appendage-bearing suspensors.Hesseltinello vesiculosa, the only known species of the genus, produces its stalked sporangiolum-bearing structures in lateral, subterminal, or terminal clusters. Only one sporangiolum is formed per fertile vesicle; sporangiolar appendages are acicular with flattened, hexagonal bases, and zygospores are unknown. The fungus is presumably heterothallic. InRadiomycesthe sporangiolum-bearing branches always arise terminally on the enlarged apex of the sporangiophore and many sporangiola are formed per fertile vesicle; sporangiolar appendages are capitate or spathulate; zygospores are as described above, and the taxa are homothallic. A new species,Radiomyces mexicana, is described. This species resemblesR. embreeibut differs in having: 1) somewhat smaller spore-bearing structures, 2) globose to obpyriform (not sphaeroidal) fertile vesicles, 3) relatively thick-walled sporophore vesicles and fertile vesicles, 4) a slower rate of sporangiospore germination, and 5) a lower upper temperature range for good growth. On certain media a variable percentage of zygosporangia are ovoid to ellipsoid and the sporophore often has a pronounced subsporangial constriction. A cladistic analysis revealed that the genera of Radiomycetaceae and the family are each monophyletic.Radiomyces embreeiandR. mexicanaare more closely related to one another than toR. spectabilisbecause they are unispored (a synapomorphy).Radiomyces embreeiandR. mexicanaare characterized by autapomorphies and are considered monophyletic. Keys to the genera and species are provided.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026077

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTMating tests were performedin vitroto determine interfertility patterns among eastern North American populations ofPeniophora cinera, and two sympatric sibling species of theP. cinereacomplex in Europe. No intersterile groups were detected in eastern North America. Reproductive isolation between the two European species reported previously by Hallenberg was verified. Since one sibling species is apparently restricted to the wood ofFagus sylvatica, speciation accompanied by substratum specialization is indicated. Intercontinental pairings showed that AmericanP. cinereais partially reproductively isolated from the two European sibling species.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026078

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTGermination of ascospores inEpichloe typhinawas described earlier as iterative germination in which each part spore of an ascospore germinated and produced conidia without an intervening mycelial phase. In the present study it was determined that the conidia produced by iterative germination also undergo an additional series of microcyclic conidiations. Thus, conidia produced from the ascosporic microcyclic structure germinated and produced other conidia, which also germinated producing yet another microcyclic structure. It was only after the third stage of microcyclic conidiations that mycelial development occurred. Microcycle conidiation inE. typhinais viewed as an obligate developmental sequence since no alternative process was observed. This distinguishes it from microcycle conidiation reported in other fungi where microcycle conidiation is facultative, being inducible only under certain laboratory conditions. Although unexplored, microcyclic conidiation may be a fundamentally important aspect of the life history ofE. typhinaand a variety of other fungi.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026079

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTMicrocycle conidiation and nuclear events during conidiogenesis inCercospora kikuchiiare described. During conidiogenesis a single nucleus migrates into the conidial initial and subsequently gives rise to all nuclei in the conidium. Mature conidia include 13–27 cells, most of which are uninucleate. Many conidia were found to form conidiophores which bore secondary conidia (microcycle conidiation). In such conidia either apical or basal cells, or both kinds of cells formed conidiophores. These events inC. kikuchiiare compared to similar events in other fungi and their implications are discussed.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026080

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTSpeciation and species concepts were investigated for theCollybia dryophilacomplex. Mating compatibility studies show that all members of theC. dryophilacomplex have a heterothallic tetrapolar mating system and that several intercompatible groups are broadly distributed over several continents including North America, Europe and Asia. Intersterility between different groups is associated with isozyme differences. Isozyme variation between some pairs of intercompatible mating groups from different continents suggests that geographic isolation (allopatry) may be important during speciation in these fungi. Combined evidence from mating compatibility, isozymes, DNA hybridization, and morphology were used to assess patterns of divergence associated with speciation. Results of phylogenetic analysis indicate that speciation in these fungi is gradual and involves many steps that are not linked in any particular sequence with the development of prezygotic intersterility barriers. Varying patterns of speciation in these and other fungi have important implications for the species concept. Limitations of the biological species concept are discussed, and instead a phylogenetic based species concept is proposed, which provides information about evolutionary relationships among allopatric mating groups based on combined data from mating compatibility, morphology and macromolecules. New combinations are proposed forC. ociorssp.brunneolaandC. alpinassp.subsulphurea.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026081

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACTPenetration and colonization of orchardgrass byRhynchosporium orthosporumand production of conidia by the fungus were investigated by light, fluorescent, and scanning electron microscopy. Conidia ofR. orthosporumgerminated to produce an appressorium, and the fungus penetrated directly through adaxial or abaxial leaf surfaces. After penetration, mycelium proliferated in the intercellular subcuticular region. Hyphae became intracellular after disintegration and death of the mesophyll cells. At this stage, symptoms were evident on leaf blades as irregular lenticular lesions. Conidia were produced on leaf surfaces from subcuticular mycelium on short conidiophores that extruded through stomata and cuticular holes. During early stages of tissue colonization, masses of conidia developed and matured on and above the intact cuticle. Subcuticular mycelium remained protected by the cuticle for most of the period of spore production.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026082

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Protoplast fusion and nutritional complementation between auxotrophic mutants ofMicrosporum gypseumhas been achieved. The highest recombinant frequency (1%) was obtained between fused protoplasts of phenylalanine and glutamic acid auxotrophs using a solution that contained 35% polyethylene glycol, 1 M KCl, 0.05 M CaCl2and 0.05 M glycine with pH 6.1. Among different minimal media tested, minimal medium 2, which had a high sulphur content, supported the best growth of the fusion products. The hybrid colonies were slow growing, irregular in shape, with diminished sporulation and a wide range of pigmentation. Most of the hybrid colonies on complete medium segregated readily into two types of parental auxotrophs by producing distinctive sectors. These segregations suggested that the colonies were heterokaryons. This study was undertaken to elucidate the mechanisms of protoplast fusion and to understand complementation of nutritionally deficient mutants of dermatophytes.

ISSN:0027-5514    

DOI:10.1080/00275514.1991.12026083

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor