摘要:

Basidiospores of 13 North American species of Strobilomycetaceae were examined by scanning electron microscopy. Similarities and differences of surface features among species are discussed in relation to their possible role in the taxonomy of the family.

ISSN:0008-4026    

DOI:10.1139/b71-177

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The normal sequence of pollen development in Douglas fir is described and is essentially the same as that forPinus. Mature pollen grains normally consist of five cells: two lens-shaped prothallial cells, a stalk cell, a body cell, and a large tube cell. The normal sequence of development is described as well as the structure and histochemistry of the spore wall. Possible reasons are given for earlier misinterpretations of pollen development and spore wall structure in Douglas fir.

ISSN:0008-4026    

DOI:10.1139/b71-178

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

InRhytisma acerinum, the apothecial primordium differentiates simultaneously into three layers: (1) roof, (2) hypothecium, and (3) basal stroma. By contrast, the primordium ofR. punctatumdifferentiates initially into two layers, the upper one becoming the roof, the lower then differentiating further into hypothecium and stroma. Asci and paraphyses of both species originate in the hypothecium. InR. punctatum, uni- or bi-nucleate ascogenous initials occur near the bases of the paraphyses, binucleate initials apparently resulting when two uninucleate elements fuse. A binucleate initial may then (1) develop into a single ascus, (2) elongate slightly and produce several outgrowths which become asci, or (3) develop into a septate or aseptate ascogenous hypha bearing a number of asci. These three developmental patterns also occur inR. acerinumthough ascocarps of this species were too mature to show unproliferated initials. Conjugate division in proliferating ascogenous elements is inferred from the frequent occurrence of nuclei in closely associated quartets or pairs. The systematic position ofRhytismais evaluated and it is proposed that the genus be removed from the Hypodermataceae Rehm sensu von Arx and Müller and placed in the Rhytismataceae Chev.

ISSN:0008-4026    

DOI:10.1139/b71-179

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Numerous bristles were detected on colonies ofScenedesmusstrain 614 when examined with the electron microscope. These appendages may be 200 μ long, occur in groups, and originate from openings in the outer layer. Bristles are composed of longitudinal microstrands, with an organized crossbanding. There is some discussion concerning bristle function, as well as reasons why others have failed to observe them in previous ultrastructural studies with strain 614.

ISSN:0008-4026    

DOI:10.1139/b71-180

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

An open system of gas analysis was used to study the kinetics of the short postillumination CO2burst (PIB) from soybean leaves. After correcting for the sample volume in the gas analyzer (IRGA), we found that the maximum measurable rate of CO2evolution occurred within 8 s after the sudden reduction in light intensity, lasted for about 6 s, and then declined rapidly. The corrected rate was 45% higher than the rate indicated by the IRGA output. The maximum rate of the PIB was proportional to the effect of light intensity on the preceding apparent rate of photosynthesis in 21% O2and 350 ppm CO2. A similar proportionality was found between the PIB and the light intensity in each of the five parts of the visible spectrum which were tested. No PIB was found when the O2concentration was reduced to less than 2% O2. The effect of 21% O2on the rate of CO2evolution after 8 s in the dark relative to the rate in 2% O2was about 20% greater than the effect of 21% O2on apparent photosynthesis in the preceding light period. This difference may be ascribed to internal refixation during photosynthesis.The results supported the theory that photorespiration continues for a short period longer than photosynthesis after a sudden reduction in light intensity. This period is much shorter than previous papers have indicated. The action spectrum for the PIB provides no support for flavin-activation as the mechanism of the light effect.

ISSN:0008-4026    

DOI:10.1139/b71-181

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The brackish-water diatomCyclotella crypticais a polymorphic species. Nine clones are capable of producing the valve pattern characteristic of the speciesC. meneghiniana, as well as theC. crypticapattern. A study of the effects of salinity and freshwater conditions on the morphology of the valve shows that the cryptica pattern is produced in salinities of about 4.3‰ to full-strength seawater, 28.7‰. The "meneghiniana" pattern is the freshwater or low salinity (1.4‰) form. Characteristics of the valve morphology and life history stages which distinguishC. crypticafromC. meneghinianaandCyclotellasp., clone 03A, are presented and discussed.

ISSN:0008-4026    

DOI:10.1139/b71-182

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Because seeds of American basswood,Tilia americanaL., exhibit a pronounced dormancy, and germinate irregularly (often only after 1 or more years of incubation), it is difficult to obtain aseptic seedlings for mycorrhizal studies. Techniques were developed to inoculate rooted cuttings with ectomycorrhizal fungi,Cenococcum graniforme(Sow.) Ferd. & Winge, andLactariussp. After 6 months, mycorrhizal inoculation was successful. The results indicate that this technique will produce adequate experimental material of this hard-seed species to permit studies of mycorrhizal relationships.

ISSN:0008-4026    

DOI:10.1139/b71-183

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Buffer-soluble proteins extracted from six morphologically different isolates ofVerticilliumwere separated by polyacrylamide gel-electrophoresis. Protein patterns from the six isolates were different from one another whether extracts were prepared from conidia, from young colonies composed of mycelium and conidia, or from 6-day-old mycelium. However, the nature of the patterns, and therefore the degree of differences among species patterns, was influenced by the types of cells from which the extracts were prepared.Patterns of proteins fromV. tricorpus, V. nigrescens, and an isolate of uncertain identity (isolate 2) which produced chlamydospores and dark mycelium were clearly different from one another whether extracts were prepared from conidia or mycelium. In contrast, conidia ofV. albo-atrum, ofV. dahliae, and of an isolate which did not produce pigmented structures produced very similar patterns which differed by only a few protein bands. This close similarity of patterns supports the view thatV. albo-atrumandV. dahliaeare genetically closely related.The protein composition of conidia differed from that of mycelium. InV. albo-atrum, spore extracts contained at least three proteins not detected in mycelium extracts. Differences between spores and mycelium were even greater inV. nigrescensand isolate 2. Analysis ofV. dahliaeshowed differences between spores, 3-day-old mycelium, and 6-day-old mycelium.Our results support the view that gel-electrophoresis of proteins is useful as a taxonomic tool provided attention is given to the degree of morphological differentiation of the materials to be compared.

ISSN:0008-4026    

DOI:10.1139/b71-184

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

An open gas exchange system that uses an infrared gas analyzer and an ionization chamber to measure CO2and14CO2is described. The system will continuously measure the CO2and14CO2exchange from a leaf within 30 s after the14CO2gas mixture is supplied to the leaf. Measurements are obtained under steady rate conditions since the14CO2gas mixture is supplied at a constant composition from pressurized cylinders. Methods of determining true photosynthesis, apparent photosynthesis, CO2evolution, and the specific activity of the14CO2evolved are clearly described. The rate of CO2evolution in the light was not affected by the CO2concentration and the evolved CO2was derived from the early products of photosynthesis.

ISSN:0008-4026    

DOI:10.1139/b71-185

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The ectomycorrhizae ofCercocarpus montanusRaf. andCercocarpus paucidentatusBritt. displayed morphologies ranging from single swollen short lateral roots on long roots to terminal pyramidal clusters. Most short roots appeared to be mycorrhizal, althoughC. paucidentatuswas only infected under growth chamber conditions. Histological sections revealed a conspicuous fungal mantle, averaging 30 μ in thickness, and a Hartig's net.The root nodules appeared as swellings on lateral roots, and later formed compact coralloid orange-colored masses several centimeters in diameter. Histological analyses indicated that both species ofCercocarpusharbored a similar endophyte. Three developmental stages were noted in cortical tissue, including (a) hyphal masses in apical nodule cells; (b) hyphae terminating in 3 × 4 μ club-shaped vesicular swellings; and (c) older structureless hyphal masses in cells of mature nodule branches. The older hyphal masses did not appear to be absorbed by the host plant. The endophyte possessed branching filaments 0.5 μ in diameter and was considered to be an actinomycete.

ISSN:0008-4026    

DOI:10.1139/b71-186

出版商:NRC Research Press    

年代:1971

数据来源: NRC