摘要:

Meria harposporioidesis described as a new hyphomycete attacking ciliated protozoans. The crescent-shaped conidium attaches to the host pellicle, invades the cell, and produces branching chains of beadlike assimilative hyphae. A unique feature is that assimilated nutrient is passed back out through the original penetration tube to the infective conidium which then produces fertile hyphae and phialoconidia. This is the first record of a hyphomycete attacking ciliated protozoans.

ISSN:0008-4026    

DOI:10.1139/b82-130

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Thirty-one species of vascular plants commonly occurring in the Boreal Forest Region of northeastern Ontario were examined for the presence of mycorrhizae. Two species were ectomycorrhizal, 3 both ecto- and endo-mycorrhizal, and 15 endomycorrhizal. Two species of Ericaceae had ericoid mycorrhizae and one had both ericoid and arbutoid mycorrhizae. Eight species, unexpectedly including three species of Rosaceae and two of Saxifragaceae, completely lacked mycorrhizae. The significance of the findings concerning the Betulaceae,Fraxinus, the Ericaceae, Rosaceae, and Saxifragaceae are discussed, as is occurrence ofCenococcum-type infections among the species.

ISSN:0008-4026    

DOI:10.1139/b82-131

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Xanthomonas vesicatoriainfection of pepper leaves was monitored by scanning electron and light microscopy. During incubation the bacteria became located in the intercellular spaces between the mesophyll cells. The primary infection sites were the vein areas.Xanthomonas vesicatoriareach high population levels on the leaf surface but usually not in the stomata. Necrosis was first observed microscopically 120 h after inoculation near the leaf veins. Bacteria were detected in infected tissue but not in necrotic tissue.

ISSN:0008-4026    

DOI:10.1139/b82-132

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A comparison of the dye-binding method of Bradford (1976) with the Folin phenol method of Lowry et al. (1951) for the assay of protein in chlorophyllous tissue is described. Additions of chlorophyll to protein standards precluded reliable determinations with either method. Absorbance readings were increased by nearly 20% with the Bradford assay and by over 400% using the Lowry procedure. Trichloroacetic acid precipitation of the proteins effectively eliminated any significant interference by chlorophyll; however, the practice of washing the protein precipitate with 80% acetone to remove residual chlorophyll resulted in large protein losses. Eluting leaf tissue with acetone prior to extraction of protein increased protein yield significantly. Both assay procedures provide satisfactory measurement of leaf proteins once chlorophyll is removed. The dye-binding method is fast, simple, and more sensitive, but the Lowry procedure gives better linearity at high protein concentrations and better stability once color has developed.

ISSN:0008-4026    

DOI:10.1139/b82-133

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Eupenicillium ochrosalmoneumScott & Stolk formed cleistothecia in insect-damaged and fungus-infested preharvest corn from fields near Tifton, GA. When fungus-infested ears were incubated in moist chambers (21 days dark incubation; 25 °C), large numbers of immature sclerotioid cleistothecia (50–150) developed within individual kernels, often filling them. The cleistothecia were exposed by removing sections of the kernel pericarp. Isolates ofE. ochrosalmoneumthat were obtained from individual surface sterilized cleistothecia proved to be prolific cleistothecial producers. Cleistothecia also formed within kernels inoculated after autoclaving. Production of the teleomorphic state typical ofE. ochrosalmoneumwas observed when these kernels were incubated up to 10 weeks. This represents the first time that any species assigned to the Trichocomaceae has been shown to form cleistothecia within the seeds of vascular plants. Citreoviridin, a potent neurotoxin, was produced in culture media inoculated with one of the isolates (NRRL 6568).

ISSN:0008-4026    

DOI:10.1139/b82-134

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

An enzyme synthesizing galactinol, UDP-D-galactose:myo-inositol-1-α-D-galactosyl transferase (galactinol synthase), has been isolated and partially purified from mature leaves ofCucurbita pepo. The enzyme showed optimal activity between pH 7.5 and 8.0 and required Mn2+and the presence throughout isolation, storage, and assay of a sulfhydryl protectant (β-mercaptoethanol). EDTA was completely inhibitory. From a range of metal ions only Mg2+partially replaced Mn2+, while Co2+, Zn2+, Cu2+, and Ni2+were inhibitory. The uridine nucleotides and UDP-glucose were from 40 to 80% inhibitory and probably constitute part of thein vivocontrol system. High concentrations of galactose, melibiose, and xylose were partially inhibitory. The enzyme appeared highly specific formyo-inositol and showed no ability for galactosyl transfer to any other naturally occurring sugar or sugar alcohol. Some reactivity was obtained with the isomericscyllo-inositol but the product was not identified. A range of other sugar nucleotides were unreactive.

ISSN:0008-4026    

DOI:10.1139/b82-135

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Aboveground plant biomass and litter measurements were made at four intervals between mid-June and late August 1977 on a subarctic salt marsh located at North Point on the southwestern shore of James Bay, Ontario. We sampled six salt marsh zones ranging from a lower intertidal flat dominated by the grassPuccinellia phryganodesto the edge of willow thickets characterized byJuncus balticus.Peak aboveground biomass was reached in nearly all zones by early August, and ranged from 119.3 to 240.4 g dry weight∙m−2. Litter accumulated in all zones except the lower two zones which were subjected to tidal flows. The highest zone whereJuncus balticusoccurred had the highest litter mass, 572.8 g dry weight∙m−2, while the lowest, 24.7 g∙m−2, occurred in the lowest zone. Estimates of net aerial primary productivity using Smalley's method ranged from 119.3 g∙m−2in the upper salt marsh to 384.0 g∙m−2in the zone dominated byJuncus balticus. The mean marsh net aerial primary productivity was 227.7 g∙m−2which was low compared with other salt marsh data. The 1977 aboveground biomass was lower in 1976, probably as a result of a co

ISSN:0008-4026    

DOI:10.1139/b82-136

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Fifteen monocotyledonous species were separately inoculated with spores ofErysiphe graminisf. sp.hordei(a parasite of barley) andE. cichoracearum(a parasite of cucurbits) to learn cytologically what types of parasite failures and host-cell responses protect nonhosts from disease. Tissues were stained with acid fuchsin and aniline blue, 24 and 72 h after inoculation, and examined microscopically. For each combination of higher plant species and fungus, fungal development and host responses were recorded for 2022–4679 spores and 15–2206 germlings, using a binary pathway system to tabulate and statistically analyze results.Nonhosts showed a battery of defenses, each of which could stop a large part of an attacking powdery mildew population. These defenses were expressed sequentially during fungal differentiation, leading to a progressive attrition in the number of germlings able to continue. The defenses were expressed on or in the following host structures: (i) the leaf surface, which was often inhospitable to germination and differentiation of infection structures; (ii) the cuticle and cell wall, which the fungi frequently failed to penetrate; (iii) the papilla, which was frequently induced but rarely penetrated; and (iv) the first cell invaded, which had a high probability of collapsing hypersensitively in the relatively few instances in which the fungi successfully entered a cell.Erysiphe cichoracearumgerminated poorly and rarely developed beyond the appressorial stage on any monocotyledonous nonhost, suggesting that monocotyledonous leaf surfaces are unsuited for growth and differentiation of this fungus.Erysiphe graminisrarely developed beyond the appressorial stage on members of the Iridaceae and Liliaceae, suggesting that leaf surface environments in these plant families contain substances unfavorable for powdery mildew development.On species within the Graminae,E. graminisf. sp.hordeigerminated and produced appressoria at lower rates on plants thought to be resistant to all powdery mildews (indiangrass, sorghum, big bluestem, and corn) than on plants which are susceptible to certainformae specialesofE. graminis(wheat, oats, and rye). Thus, within the Graminae, the amount ofE. graminisdevelopment on nonhosts was negatively correlated with taxonomic distance between nonhost and appropriate host. However, the results with other combinations of fungus and nonhosts suggest that fungus development is usually controlled by resistance factors which are characteristic of the plant family and are unrelated to the taxonomic distance between nonhost and appropriate host.

ISSN:0008-4026    

DOI:10.1139/b82-137

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Plants ofDesmodium paniculatum(Leguminosae) were grown from seeds in normal air (0.035% CO2) and in air containing 0.1% CO2. CO2enrichment produced an almost twofold increase in dry matter production. Leaf areas were 1.2 times higher at high CO2. Relative growth rates under high CO2were significantly higher during the early stages of development and then declined. The increase in dry matter production was not associated with an increase in photosynthetic capacity per unit leaf area. Gas exchange measurements indicated that plants from the high CO2regime had lower light saturation values and lower photosynthetic rates at high quantum flux densities than the controls. An opposite trend was observed if gas exchange rates were expressed on a chlorophyll basis. The depression in photosynthetic rates on a leaf area basis of plants exposed to CO2enrichment was correlated with increased starch accumulation and reduced grana formation in chloroplasts of leaves continuously exposed to high CO2concentrations.

ISSN:0008-4026    

DOI:10.1139/b82-138

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Development of the thraustochytridUlkenia amoeboideawas investigated at the ultrastructural level. The mature thallus possesses a lamellate wall, a nucleus with intranuclear vesicles and lamellae, several Golgi bodies, mitochondria, bundles of microfilaments, multivesicular bodies, dilated perinuclear continuum with filamentous material, endoplasmic reticulum, sagenogenetosomes, and two centrioles. Several unit membrane bounded, variously electron-dense inclusion bodies with electron-dense globular units are present. Wall scales are produced in Golgi cisternae which inflate to form vesicles. These vesicles deposit the wall material to the outside by exocytosis. An aggregate of unit membrane bounded electron-dense cisternae (paranuclear body) is found adpressed to the nucleus. A close association between the paranuclear body and the mitochondria, the former often producing finger-like projections in mitochondrial vicinity, is present. A protocentriole-like structure is seen near the nucleus of young thalli. At later stages, the ectoplasmic net elements disappear. Closely adpressed membrane arrays appear between the cell wall and plasmalemma. These are accumulated in bundles at various places in the cell and are later found in presumed autophagic vacuoles. Before the cell contents escape as an amoeboid mass, the cell wall becomes thinner owing to the peeling off of wall scales and the cell contents round up, with the plasmalemma becoming detached from the cell wall. Various vesicles are closely associated with the plasmalemma.

ISSN:0008-4026    

DOI:10.1139/b82-139

出版商:NRC Research Press    

年代:1982

数据来源: NRC