摘要:

Scanning and transmission electron microscopic examinations of the stromata ofPodosordaria leporinaandPoronia oedipusare reported. Stromal shape, conidiogenesis, and ascospore morphology of these two species are compared. A comparison of the taxonomic concepts ofPoroniaandPodosordariais presented. It is suggested thatPodosordaria leporinashould be transferred back toPoronia.

ISSN:0008-4026    

DOI:10.1139/b75-249

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Early developmental stages of the sorus inCyathea fulvashow that the indusium is initiated from cells of the protoderm on the abaxial leaf surface, closer to the midvein than the margin of the ultimate segment. This contrasts with earlier work onAlsophila tricolorthat reported a marginal origin of the indusium and possible phyletic relations with the marginal sorus in the Dicksoniaceae. This new information is considered in an assessment of the numerous forms of the indusia in five genera of the Cyatheaceae. A series of photographs shows the principal forms and the diversity of sori and indusia inSphaeropteris,Alsophila,Nephelea,Cyathea, andCnemidaria, including species of both the paleotropics and neotropics. The figures illustrate the inadequacy of the earlier system of classification of these plants in three main genera based upon the type of indusium. The primary role of the indusium is considered to be the retardation of water loss during sporangial development and sporogenesis.

ISSN:0008-4026    

DOI:10.1139/b75-250

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Studies on the germination ofTrichoderma viridespores indicate that they lose their resistance to heat at an early stage of germination. Whereas dormant conidia were resistant to 46 °C, the same treatment given 4 h after the onset of germination was lethal to the germinating spores. A milder thermal treatment (45 °C for 10 min) given during the first 2 h of incubation caused a delay both of swelling of conidia and appearance of germ tubes.Sensitivity of spores to heat was dependent on the temperature, duration of treatment, and incubation in a nutrient medium before application of the thermal treatment.Increase in oxygen uptake, rate of protein synthesis, and RNA synthesis were observed 2–3 h after the onset of germination. Ultrastructural changes were first observed after 4 h of germination. Application of the mild thermal treatment during the first 2 h of germination resulted in a delay in the observed increase in oxygen uptake, protein synthesis, swelling, and ultrastructural development, as well as emergence of germ tubes.

ISSN:0008-4026    

DOI:10.1139/b75-251

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A detailed comparison of the gross morphology of hyphae, monilioid cells, and sclerotial formation and structure of 17 isolates of species in seven genera of theRhizoctoniacomplex were studied. Cytochemistry of both hyphal and sclerotial cells was also studied. Gross morphology of hyphae was similar in many of the isolates and was considered of limited taxonomic value. Sclerotial formation in species ofThanatephorus,Waitea,Aquathanatephorus, and possiblyCeratobasidiumwas of the monilioid cell type. That ofAtheliawas of the hyphal strand type. Although initially similar, mature sclerotia in each of the genera showed great diversity. Most sclerotia ofThanatephoruswere constructed of loosely arranged monilioid cells. Those inCeratobasidiumdeveloped a marginal rind;Aquathanatephorus, a pitted surface and hyphal mat;Waitea, a bilaminate condition with elongate marginal and globose medullary cells; andAthelia, a complex tetralaminate structure. Distribution and concentration of carbohydrates, proteins, and lipids differed in the various genera. The strong dextrinoid reaction of the cytoplasm ofThanatephorusandAquathanatephorus, accompanied by higher total lipids in cell walls and septa, was of significance. Stronger reactions for cellulose were found in species ofCeratobasidium, while cellulose appeared more concentrated in sclerotial cells than in hyphal cells ofThanatephorus. Lipids were deposited more abundantly in sclerotial cells than in hyphal cells.

ISSN:0008-4026    

DOI:10.1139/b75-252

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Three new species of ascomycetes and two coelomycetes are described from diseased Douglas fir (Pseudotsuga menziesii(Mirb.) Franco) from coastal British Columbia, Canada, viz.,Coccomyces pseudotsugaen. sp.,Phragmoporthe pseudotsugaen. sp., andBotryosphaeria pseudotsugaen. sp.;Phomopsis portein. sp. andHaplosporellasp. are associated with the latter two ascomycetes, respectively, and possibly represent their conidial states.

ISSN:0008-4026    

DOI:10.1139/b75-253

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The growth-substance content of fruits ofElaeagnus umbellatawas examined as part of an investigation of the regulation of seed dormancy of this species. Extracts of dormant seed fractions were separated chromatographically in various solvents and biological activity was determined in a lettuce-seed and a cucumber-seed bioassay. The bioassays showed that a growth-inhibiting substance with anRfvalue similar to coumarin was present throughout the dormant seed. Fluorescence also showed that the inhibitor closely resembled coumarin.Activity of the inhibitor did not decrease during 90 days at 5 °C, and evidence indicates it may be physiologically active in preventing germination. On the other hand, germination-promoting substances that may counteract the effect of the inhibitor were found to be produced in the embryo during low-temperature afterripening.

ISSN:0008-4026    

DOI:10.1139/b75-254

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Leaf surface patterns ofAcer saccharumMarsh. were investigated from extremely polluted and relatively unpolluted locations in Montreal, Quebec. In the polluted locations, the values for stomatal frequency were lower, and for trichome density higher than the corresponding values in the relatively unpolluted locations. No variation was evident in the subsidiary cell complex. These patterns may suggest adaptive significance in polluted environments.

ISSN:0008-4026    

DOI:10.1139/b75-255

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Carrageenans from gametangial (male and female) and tetrasporangial plants of the red algaIridaea cordatawere isolated, fractionated, and characterized on the basis of their anhydrogalactose and sulfate content and infrared spectra. As in the case ofChondrus crispasthe tetrasporangial plants yielded only λ-carrageenan while the gametangial plants produced carrageenans of the κ-type. The male plants yielded proportionately more KCl-insoluble κ-carrageenan than did the female. The infrared spectra of the various preparations fromI.cordatawere virtually indistinguishable from those of comparable fractions isolated fromC.crispus.

ISSN:0008-4026    

DOI:10.1139/b75-256

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Nalidixic acid bleachedLemna minorduring growth in white light on a medium supporting heterotrophic growth. Immature, vacuolate mesophyll cells from bleached tissue contained plastids with aberrant thylakoids and had less-electron-dense cytoplasm than normal cells. Mitochondrial shape appeared normal. Individual bleached plants regreened and regained normal rates of growth after transfer to nalidixic-acid- (NAL-) free medium. Frond multiplication was also inhibited by NAL during growth in darkness. Purine and pyrimidine ribonucleosides did not prevent NAL-induced bleaching or growth inhibition.

ISSN:0008-4026    

DOI:10.1139/b75-257

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Septal ontogeny inLinderina pennisporaRaper & Fennell is initiated by the ingrowth of material from the inner of the two layers of the cell wall. The growing point of the septum bifurcates and continues growth, forming a lenticular cavity into which the septal plug is deposited. This type of septal development occurs in all septa except those produced between the pseudophialides and the merosporangia and spores. The latter septal type initially is formed as previously described, but then additional wall material is produced both above and below the septum. In the merosporangiospore three layers of wall material are produced, the inner two layers give rise to the spore spines, and at maturity all wall layers coalesce and form a single, thick spore wall. Extra wall material in the apex of the pseudophialide gives rise to a multilobed and mottled vacuole that shrivels just before spore liberation. Mature merosporangiospores are the only structures with spore spines. Aerial spines are produced on all structures except the merosporangiospores, although a relatively larger number of the aerial spines are produced on the aerial hyphae than on the pseudophialides and the sporocladia. The possible functions of the spore spines and the aerial spines are discussed.

ISSN:0008-4026    

DOI:10.1139/b75-258

出版商:NRC Research Press    

年代:1975

数据来源: NRC