摘要:

ABSTRACTThe subcellular location of carbohydrates in secondary zoospores ofSaprolegnia feraxwas determined from an electron cytochemical study. Specificity of reactions was verified with the sulfhydryl blocker iodoacetate, and the dialdehyde blocker dimedone. Although no cell coat was visible on the zoospore surface, the plasma membrane and the flagellar sheath contained an abundance of carbohydrate and sulfhydryl compounds. Deposition of reaction product and results of controls demonstrated that similar compounds were also on membranes of the water expulsion vacuole system. Peripheral vesicles contained reaction product over their fibrous contents, demonstrating the presence of carbohydrates, and controls indicated that sulfhydryl groups were most likely also present. Sulfhydryl-containing carbohydrates and other carbohydrates were compartmentalized in the tubule-filled cavity of kinetosome-associated organelles (K2bodies), while their granular matrix was unreactive. Vital roles of carbohydrates in oomycetous zoospores are incompletely understood, but this study suggests mechanisms through which they may function in the stability and recognition of membranes. This is the first report of carbohydrates in K2bodies and provides a basis to explore the function of this novel organelle.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025563

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTThe species composition of vesicular-arbuscular mycorrhizal fungi (VAM) are described from experimental plots in tallgrass prairie at Konza Prairie Research Natural Area, Manhattan, Kansas. Treatments include topography (four positions downslope) and burning frequency (annually burned and infrequently burned). Multivariate and univariate analyses indicate that gradients of variation in VAM species are related primarily to topography and burning frequency, and secondarily to original plot position within experimental rows. Spore numbers of seven of the most abundant species are directly related to topography; three of these also show an interaction with burning frequency. Although the distinction between direct and indirect effects of topography and burning frequency cannot be made with these data, a parallel response of vascular plant species frequency to the topographic gradient was observed.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025564

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTEpichloëtyphinaand fungi thought to be closely related to it are widespread as endophytes in the Poaceae. Based on biological features of the fungus-host relationship, associations may be classified as one of three types. In type 1 associations, stromata form on most of the plants harboring endophytes. This type of association has been found in several subfamilies of grasses and sedges. In type 2 associations, stromata are formed on very few of the numerous infected individuals, while in type 3 associations stromata have not been observed on infected plants. The latter two associations are known to occur only in the subfamily Festucoideae. It is evident that coevolution has occurred betweenEpichloespp. and festucoid grasses resulting in the evolution of mutualisms from primarily pathogenic relationships. It is suggested that this has occurred by selection of grass individuals which possessed the ability to suppress stromata formation by the endophytes. The mechanism for suppression of stromata may involve production of alkaloids which inhibit growth of these fungi.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025565

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTOlder conks ofGanoderma applanatumwere observed to have a whitened appearance in the context and older tramal tissues and were similar in this respect to white-rotted wood. Hyphae taken from whitened areas of the context became greatly expanded when mounted in 2% KOH and showed signs of deterioration when viewed microscopically. Holes and spore wall erosion were present in basidio-spores trapped in the current year's pore layer. Nitrogen levels and relative densities were lower in the whitened areas than in the brown current year's growth. Comparisons of relative densities between older and newer tissues of the brown rot fungusFomitopsis pinicolaindicated little difference. However, as inG. applanatum, N levels were lower in older tissues ofF. pinicola.Recycling of nutrients from older nonfunctional tissues inG. applanatumandF. pinicolaconks may be a mechanism whereby nutrients are transferred to the current year's growth. However, the whitening phenomenon and reduction of hyphal number was peculiar only to some olderG. applanatumconks. Hyphal decay (autolysis) may be a mechanism of N utilization in conks of this fungus.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025566

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTNicotine, at concentrations of 1000–3000μl/L in distilled water, induced vacuole formation in teliospores ofUromyces vignae, the causal agent of cowpea rust,Puccinia punctiformis, the causal agent of Canada thistle rust, andPuccinia helianthi, the causal agent of sunflower rust. Induced vacuoles accumulated the vital stain, neutral red, when buffered at high pH values. Vacuole induction by nicotine indicates that the cell walls of these teliospores are permeable and that the inability to germinate is not caused by complete cell wall impermeability.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025567

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTBotryosphaeria pipturiis described as new, andAlographina eucalypti, Rigidoporus ulmarius, Phaeoseptoria eucalypti, Dothistroma septospora, Septoriaspp., andMycosphaerellaspp. are newly reported from Hawaii.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025568

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTThe relatedness between fourPhytophthora megaspermaisolates [P. megaspermaf. sp.glycinea(Pmg) from soybean,P. megaspermaf. sp.medicaginis(Pmm) from alfalfa, and two broad host-range isolates from apple or alfalfa],P. cactorum, P. cryptogea, andP. parasiticavar.nicotianae(Ppn) was investigated by a quantitative analysis of restriction fragment length polymorphisms of mitochondrial DNAs. Nucleotide sequence divergence values amongP. megaspermaisolates were within the same range as between theP. megaspermaisolates and the three otherPhytophthoraspecies. An unrooted phylogenetic network based on nucleotide sequence divergence values indicated that several evolutionary lines exist forP. megasperma.These data are consistent with the observed variability of morphological, physiological and biochemical characteristics within this fungal group and support the contention thatP. megaspermacomprises several biological species which are the result of convergent evolution and which are not closely related. A consensus restriction map of the mtDNAs of Pmg, Pmm, and Ppn was constructed, and numerical analyses of conserved and variable restriction cleavage sites also support the separation of Pmg and Pmm into distinct species.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025569

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTThe septal pore apparatus ofTremella globosporawas examined in conventionally fixed and freeze-substituted hyphae. The system of saccules comprising the septal pore cap appears to be derived from several sheets of endoplasmic reticulum. Saccules and endoplasmic reticulum are connected with each other and with the plasma membrane of the septum by a series of electron dense rods. A three-dimensional reconstruction from serial sections of theT. globosporaseptal pore apparatus is presented. Interphase, prophase, and metaphase nuclei fixed with freeze substitution and with chemical fixatives were examined. The spindle pole body inT. globosporais biglobular prior to mitosis. Globular elements expand in volume approximately five fold from prophase to metaphase. The structure of the spindle pole body and of the septal pore apparatus suggest thatTremellaand related taxa may be closely related to those saprobic heterobasidiomycetes with septal swellings and imperforate pore caps.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025570

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTMorphology of basidiospores and pilocystidia of specimens ofGanoderma colossum, G. zonatum, G. oregonense, andG. meredithaewas compared. Structure of basidiospores was similar in all species, but basidiospores of some species differed in length, width, spore index, and shape and distribution of inter-wall pillars. Basidiospores ofG. zonatumwere cylindrical, while those of the other species were ovate with truncated apex. Basidiospores ofGanoderma colossumhad angular inter-wall pillars while those of the remaining species were cylindrical. Pilocystidia were davate and unbranched for most species, but those ofG. zonatumwere highly branched or lobed. Pilocystidia ofG. colossumwere thin-walled, negative to weakly amyloid. Those ofG. zonatumwere thick-walled, negative to weakly amyloid, while those of the remaining species studied were thick-walled and strongly amyloid. Host relationships are reviewed and known geographical distributions are indicated for each of the species studied.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025571

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

ABSTRACTThree new species ofRhodocybefrom a lowland rainforest of Costa Rica are described and illustrated. The new species areR. eccentricaof sect.Rhodophana, R. densifoliaof sect.Claudopodes, andR. melleaof sect.Rhodocybe.

ISSN:0027-5514    

DOI:10.1080/00275514.1988.12025572

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor