摘要:

Avena occidentalisDur., hitherto known from only one specimen, was found to occur in three islands of the Canaries and in one locality in Portugal. The speculation that this might indicate a greater past distribution is strengthened by a few examples of species with a similar present distribution in the Canaries and with known fossil records from Europe. Some morphological character states ofA. occidentalisare described and they are compared with character states from homologous organs in morphologically similar species. The possible importance thatA. occidentalismight have for the understanding of the cytogenetical relationship between theAvenaspecies is stressed, and the possible value of this species to agriculture is mentioned.

ISSN:0008-4026    

DOI:10.1139/b71-150

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The anaerobic decarboxylation of α-ketoacids by a crude extract ofRhizoctonia solaniwas investigated using a manometer procedure. The possible importance of this enzyme in the metabolism of the fungus is discussed. The best substrate for the enzyme preparation was α-ketobutyrate. Thiamine pyrophosphate and Mg2+were cofactors for the enzymic decarboxylation of α-ketobutyrate. TheKmfor α-ketobutyrate was 7.6 × 10−3moles/1, and the energy of activation was 3980 calories. Optimum catalysis for the reaction was achieved at 32°, pH 6.2. Products of the action of the enzyme preparation on α-ketoacids were CO2and the respective aldehyde. Decarboxylase activity was inhibited in the presence of Hg2+, Ag+, and norjavanicin.

ISSN:0008-4026    

DOI:10.1139/b71-151

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Zoospores ofPhaeosaccion collinsiiaveraged 70 µ3and contained total N 2.24 pg, DNA 0.19, and chlorophylla0.62 pg per spore. In addition, chlc, "cis"-β-carotene, fucoxanthin, and violaxanthin were principal pigments and a minor unidentified carotene was present.Photosynthetic rates of zoospores were 0.37 × 10−12 g C per spore per hour, or 0.59 mg C per mg chlaper hour at 5°. The principal products of photosynthesis were mannitol and a water-soluble glucan.Carbohydrates in the thalli were fractionated and evidence is presented for the presence of a laminarin-like glucan, mannitol,myo- andscyllo-inositols. Alginate was absent.The relationship ofP. collinsiito other algal groups is discussed and it is concluded that its affinities lie with the Chrysophyceae.

ISSN:0008-4026    

DOI:10.1139/b71-152

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The ascogenous hyphae ofHypoxylon microplacumoriginate from uninucleate secondary ascogonial cells. Asci are produced by way of croziers and directly from ascogenous cells. The implications of these results are discussed.

ISSN:0008-4026    

DOI:10.1139/b71-153

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A common tuberculate ectomycorrhiza of Douglas fir in the Pacific Northwest, described earlier by Trappe, is further examined and defined. Tubercles consist of an outer rind of aseptate, amber, thick-walled hyphae encasing tightly packed inner elements mantled with septate, hyaline, thin-walled hyphae. Reported as a Phycomycete and a Basidiomycete, respectively, the two hyphal forms actually belong to a single fungus,Rhizopogon vinicolorA. H. Smith; cultural characteristics of this fungus are described. Pure culture mycorrhiza syntheses with both mycorrhizal and sporocarpic isolates and Douglas-fir seedlings are reported. Antagonism tests revealed the following inhibition of root pathogens byR. vinicolor: strong—Phytophthora cinnamomiRands,Pythium debaryanumHeese, andPythium sylvaticumCampbell & Hendrix; moderate—Fomes annosus(Fr.) Cke. andPoria weiriiMurr.; and weak or none—Fusarium oxysporumf.pini(Hartig) Snyd. & Hans.,Pythium ultimumTrow,Rhizoctonia solaniKuehn, andMacrophomina phaseoli(Maubl.) Ashby.

ISSN:0008-4026    

DOI:10.1139/b71-154

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

It is generally considered that the production of new strains of rust by somatic hybridization cannot be adequately explained by hyphal anastomosis and nuclear exchange. Such a mechanism would account for the observed recombination if, as is proposed, the rust fungi in their dikaryophase carry multiple haploid genotypes within any one phenotype. Such hidden variation could arise through whole chromosome exchange between the nuclei of a dikaryotic cell. Possible ways of generating genotypic variation within a phenotype are suggested by the results of recent investigations ofPuccinia graminisf. sp.triticiin axenic culture.

ISSN:0008-4026    

DOI:10.1139/b71-155

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Thirteen fossil mosses belonging to eight genera were extracted from a woody sapropel found in the upper Beaufort Formation, northwestern Banks Island, Western Canadian Arctic. All belong to extant species.On the basis of the enclosing strata, moss fossils, and associated organic remains it is concluded that the sediments were deposited in a small, shallow body of water, in which lake sedimentation was both preceded and terminated by alluvial sedimentation.

ISSN:0008-4026    

DOI:10.1139/b71-156

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Productivity and rate of liberation of spores from pycnidia ofSeptoria triticion green detached flag leaves of field origin and from pycnidia on artificially inoculated wheat seedlings were studied. About 40% of the total spores within a pycnidium were exuded after the initial wetting, but the final percentage of spores which oozed naturally from the pycnidium ranged from 60 to 80% of the total spores, depending on the wheat cultivar and the environmental conditions in which the infected host was grown. The pycnidia were ellipsoid and their volume was calculated for both dried and wet pycnidia. The volume of wet pycnidia varied within the range of 0.012 to 0.019 mm3, which is about a 30% increase over the dry pycnidia, whose volume varied within the range of 0.003 to 0.006 mm3. The correlation between pycnidial volume and total number of pycnospores per pycnidium was non-linear. Wetting and drying treatments had little effect on pycnospore production and liberation rate, and did not cause the production of new pycnidia on detached green leaves.

ISSN:0008-4026    

DOI:10.1139/b71-157

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Seeds of soybean (Glycine max(L.) Merrill) cultivars were surveyed for urease isoenzymes. The main isoenzymes were found to be either fast- or slow-running on acrylamide gels (Rp0.54–0.57 and 0.36–0.41 on 5% gels), and this was a varietal characteristic. Pedigree relationships and segregation in experimental crosses indicated that the isoenzymes were under the control of a single major gene pair, with fast-running dominant over slow-running. The symbolsEuandeuare proposed. The molecular weight of the slow form was about double that of the fast form. The apparent mean energy of activation of crude urease from the dominant fast form (40.5 k J/mol) was less than that of the slow form (47.9 k J/mol). Differences between the homozygous and heterozygous fast types were not detected. The simplest explanation of the results is that the slow-running type is a dimeric form of the fast type, and that the gene is controlling the degree of polymerization of the molecule. Dissociation of the slow type into a smaller unit with a migration ratio similar to that of the natural fast type but a slightly different migration rate suggests, however, that the two types may differ either in molecular conformation or in primary structure.

ISSN:0008-4026    

DOI:10.1139/b71-158

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The ultrastructure of mesophyll cells ofPinus strobushas been investigated in the spring and winter months. Wall invaginations begin in the early spring and eventually give the cells a lobed appearance. The chloroplasts are of the normal stroma lamella – grana type and completely ring the cells by winter. Lipid globules and electron-dense phenol deposits increase in the winter months.

ISSN:0008-4026    

DOI:10.1139/b71-159

出版商:NRC Research Press    

年代:1971

数据来源: NRC