摘要:

ABSTRACTProteinase formation by the brown-rot fungusPostia placentawas studied to determine whether differences in proteolytic enzyme production could be correlated with the ability to decay wood. Strain MAD698, a standard test isolate ofP. placenta, formed higher levels of proteinases in the presence of organic, rather than inorganic, nitrogen. Strain ME20, an atypical monokaryon that causes less than 5% weight loss in wood in standardized decay tests, produced elevated levels of proteinase in the presence of inorganic nitrogen. Strain ME20 was also able to metabolize nitrate, a nitrogen source not readily used byP. placenta.Proteinase production was associated with the autolytic phase of growth in both MAD698 and ME20 and was localized in the colony centers. The proteinases had acidic pH optima indicative of aspartic proteinases. The ability of an isolate to cause weight loss in wood may be related to its proteinase regulation and nitrogen metabolism.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026212

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTA unifactorial pattern of sexuality was documented for 13 stocks ofPhellinus torulosus.Incompatibility was indicated by a line of demarcation between the paired isolates; compatible pairings resulted in the formation of heterokaryotic secondary mycelium in the contact zone. Buller's phenomenon was not observed between paired heterokaryons and homokaryons. Both heterokaryons and homokaryons are without clamps and with binucleate hyphal segments. They can be distinguished as follows: 1) Fruiting only appears in heterokaryotic cultures; homokaryons never fruit. 2) Pairing of heterokaryons with other mycelia always results in the formation of a line of demarcation. 3) Nuclei with a DNA content of In, 2n and 4n can be found in heterokaryons; only In and 2n nuclei in homokaryons. 4) Growth of mycelium is slightly faster in heterokaryons as compared to homokaryons. Two partially intersterile groups ofP. torulosusare documented by pairing tests and ontogeny of secondary mycelia. One group consists of collections from Europe, mainly from the Mediterranean. The second group is restricted to the Canary Islands. No significant differences between the groups were noted in any cytological character or any macro- or micromorphological character examined. Fruiting was distinctly more common and faster in secondary mycelia derived from intragroup pairings as compared to secondary mycelia from intergroup pairings. No obvious substrate preferences were noted forP. torulosus.The taxon apparently occurs both as a parasite and a saprobe.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026213

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTThe genusThamnidiumis restricted to a single taxonT. elegansthat produces deliquescent-walled sporangia at the apex of a primary sporophore or its branches along with persistent-walled sporangiola on lateral dichotomous branchlets. In some instances only sporangia or sporangiola may be formed on a given sporophore. The dichotomous branchlets may arise singly, in pairs, or in verticels of three or more. The species is illustrated with photographs and line drawings.Thamnidium verticellatumis regarded as a synonym ofT. elegans.An extensive list of synonyms is supplied.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026214

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTThe rhizoplane mycofloras of little bluestem(Schizachyrium scoparium)were compared in unfumigated and fumigated soils to which selected inorganic nutrients were added. Thirty-four fungal taxa were isolated and 20 were common to unfumigated and fumigated soil 17 months after fumigation. Species richness (i.e., number of species) was greater on the unfumigated site (33 species) than the fumigated site (21 species). Addition of inorganic nutrients to the soil did not have significant effects on the occurrence of the eight most abundant rhizoplane species. Tests for interspecific association among the eight most frequently occurring species revealed that most of these species had significant negative associations with each other.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026215

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTSphaeronaemella helvellaeisolates were tested for mating type and the effect of substrate on compatibility and fecundity of compatible crosses. Single ascospore isolates were crossed in all combinations and their interactions analyzed. Crosses of single ascospore isolates, either in axenic culture or in association with host fungi, resulted in erratic production of perithecia. Crosses of single ascospore cultures produced perithecia in 50% of cultures when incubated on corn meal agar amended with aXanthomonassp. The presence of the bacterium or its biologically sterile filtrate inhibited mycelial growth, reduced the time for perithecial initiation, and increased the quantity of perithecia produced byS. helvellae.Perithecial production inS. helvellae, a heterothallic mycopathogen, was conditioned by a single locus. In both field population and laboratory progenies ofS. helvellae, one allele of the incompatibility locus was more frequent than the other.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026216

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTIt has been suggested that the anamorph ofOphiostoma francke-grosmanniaeis a species ofPhialocephalawith phialidic conidium development. This would make it the only species inOphiostomawith aPhialocephalaanamorph. Light and fluorescence microscopy seemed to confirm the presence of phialidic conidiogenous cells. However, scanning and transmission electron microscope observations revealed tightly packed, yet distinct annellations in the apical region of the conidiogenous cells. This is indicative of the percurrent enteroblastic proliferation that is diagnostic ofLeptographiumanamorphs ofOphiostoma.The anamorph ofO. francke-grosmanniaeshould, therefore, be disposed inLeptographium.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026217

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTDiploid-haploid pairings to identify field isolates ofArmillariato species generally rely on morphological differences between diploid and haploid colonies (flat and flufly colonies, respectively) and morphological changes in haploid tester colonies. Presumably, the change in morphology of the haploid tester is due to diploidization. Isozyme markers, aconitase and glucosephosphate isomerase, were used to follow nuclear migration from putatively diploid isolates into a haploid tester strain ofA. ostoyae.After pairing diploid field isolates with a haploid tester for 3 or 4 weeks, subcultures were taken from the hap!oid tester at 2 and 10 mm from the confrontation zone. Subcultures from 2 mm were mostly flat; subcultures from 10 mm were flufly, flat, or flufly with flat sectors. Hyphal tip cultures from the subcultures were analyzed for the isozyme markers. All flufly hyphal tip cultures had the isozyme phenotype of the haploid tester. Flat hyphal tip cultures either had the isozyme phenotype of the diploid parent or had a hybrid isozyme phenotype with markers of both the diploid parent and the haploid tester. The data suggest that in conspecific diploid-haploid pairings, the diploid nucleus usually migrates into the haploid mycelium and eventually displaces the haploid nucleus.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026218

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTUsing partial small subunit ribosomal gene sequences we show that yeast-like genera that produce galeate (hat-shaped) ascospores and similar-spored members of the Ophiostomatales do not form a monophyletic group. Based on distance and parsimony methodsCephaloascus fragransandEndomyces decipiensfailed to form a monophyletic grouping with species ofCeratocystis sensu strictoandOphiostoma.Instead these yeast species clustered withSaccharomyces cerevisiae, Kluyveromyces lactis, andTorulaspora delbrueckiiin>9% of both the distance and parsimony majority-rule consensus trees generated using the statistical method of bootstrapping. Therefore galeate ascospores appear to be an example of convergent evolution in fungi and by itself this trait should not be considered as an indicator of evolutionary relatedness.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026219

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTThe tall fescue endophyte,Acremonium coenophialum, is inhibitory to mycorrhizal fungi. This study was conducted to determine ifAcremoniuminhibits infection and the extent of colonization of roots in addition to sporulation. Fewer fescue seedlings, with or withoutAcremonium, were infected by single spores ofGlomus macrocarpumthan pearl millet seedlings. However, fescue seedlings were infected byG. mosseaesingle spores to the same extent as pearl millet seedlings. Roots ofAcremonium-free fescue were not colonized as extensively as those of pearl millet by either fungus. The presence ofAcremoniumin fescue caused a further considerable reduction in extent of mycorrhizal colonization. Effects of the host on sporulation were closely correlated with extent of colonization. Each of the three hosts supported a similar total spore volume of the two mycorrhizal fungi.Acremoniumapparently does not affect infection, perhaps because the seedlings were too young for extensive transport of toxic alkaloids fromAcremonium-infected shoot tissues to roots free ofAcremonium.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026220

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

ABSTRACTVery different microfungal species were obtained from forest soils in Rhode Island when two different isolation temperatures (0 C and 25 C) were used, even though isolates were obtained from the same samples. At 0 C, Zygomycetes, particularlyMucorandMortierellaspecies in the sectionsHygrophilaandStylospora, were favored. Most fungi isolated at 0 C were psychrotrophs capable of growing from 0 C to temperatures greater than 25 C. However, psychrophiles, mostlyMortierellaandMucorspp., were also isolated, and two newMortierellaspecies were identified. Isolations at 25 C resulted primarily in the recovery of Deuteromycetes andMortierellaspecies in the sectionIsabellina.Most of these isolates were mesophiles with growth minima between 5 and 10 C and maxima above 25 C. It is concluded that isolation temperature can seriously bias our perception of fungal species abundance, dominance and distribution in forest soils. Soil temperatures measured at 10 cm depth for 2 years in a Rhode Island forest remained at or below 10 C for 5 months of each year and did not rise above 19 C. Water potentials in the upper 15 cm of soil were greater than -0.4 MPa over the same period and were not limiting for the growth of most fungi. Therefore, low temperature fungi are potentially active throughout the year in soil of this temperate forest, whereas the activity of mesophiles may be restricted to periods when temperatures are above approximately 10 C. Isolations at 0 C should improve identification of fungi involved in decomposition processes at low temperatures.

ISSN:0027-5514    

DOI:10.1080/00275514.1992.12026221

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor