摘要:

A study of the surface microflora of mycorrhizal and non-mycorrhizal roots of yellow birch seedlings has revealed distinct quantitative and qualitative differences. Higher bacterial counts and distinctly greater numbers of actinomycetes and of methylene-blue-reducing, sugar-fermenting, ammonifying, and fluorescent-pigment-producing bacteria were found on the former. The percentage incidence of bacteria growing optimally in a simple mineral–glucose medium was greater on normal roots whereas bacteria requiring complex nutritional factors appeared to be relatively more numerous on the mycorrhizal surface. Species ofPythium, Fusarium, andCylindrocarponpredominated on, andMycelium radicis(?) was absent from, normal roots, whereas, on mycorrhizal roots,Penicilliumand other rapidly growing fungi as well asMycelium radicis(?) were numerous andPythiumandFusariumspecies absent. These results are discussed in relation to the nutrition of mycorrhizal and non-mycorrhizal roots.

ISSN:0008-4026    

DOI:10.1139/b62-037

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

This paper presents a comparative anatomical study of normal shade and extreme shade leaves of a common garden plant (Convallaria majalisL.). Striking differences in leaf form, shape, size, thickness, and internal structure were observed. The failure of the mesophyll cells to enlarge is thought to account for the marked thinness and peculiarly folded condition of extreme shade leaves.

ISSN:0008-4026    

DOI:10.1139/b62-038

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

A leaf attached to a stem segment promotes regeneration from cells of this segment while the stem segment inhibits cellular regeneration from the leaf. The age of the gametophore is found to influence greatly stem inhibition of attached leaf regeneration. Decapitation of the gametophore prior to stem segment isolation results in increased protonematal regeneration from cells of the leaf attached to this segment. Pretreatment of the plant with various concentrations of NH4NO3before stem segment isolation influences cellular regeneration from the attached leaf, higher non-toxic concentrations of NH4NO3increasing the number of protonematal regenerates per attached leaf greatly.It is emphasized that one is not dealing in the present case with specific inhibitory influences from the stem segment on leaf regeneration. The present correlation system has to be interpreted, rather, in terms of the organization of the whole gametophore, and this is attempted.

ISSN:0008-4026    

DOI:10.1139/b62-039

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Phyllody in clovers, observed on rare occasions in Canada since 1902, is now common in Quebec, New Brunswick, Nova Scotia, and Prince Edward Island. Tests in the field indicated that natural spread of the disease could occur each month from June to September. A virus causing phyllody symptoms was transmitted by the leafhoppersMacrosteles fascifrons(Stal),Aphrodes bicinctus(Schrank), andScaphytopius acutus(Say) fromTrifolium repensL. toT. repens. M. fascifronsalso transmitted the virus to and fromVinca roseaL. andCallistephus chinensisNees.S. acutustransmitted the virus toV. roseaandTrifolium pratenseL. The virus was also transmitted by dodder,Cuscuta gronoviiWilld., fromV. roseatoV. rosea. Clover phyllody virus (CPV) in Canada resembles CPV in England and Europe and both are transmitted byA. bicinctus. Although CPV in Canada is transmitted byM. fascifrons, which is a vector of aster-yellows virus (AYV), it differs from recognized strains of AYV in other vector–virus relationships, symptomatology, and geographic distribution.

ISSN:0008-4026    

DOI:10.1139/b62-040

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Experiments on excised stems of maple (Acer saccharumMarsh) in the winter and growing states have shown that artificial flow through open channels can alter the existing biopotential and thus produce local streaming potentials. On the other hand, artificially applied voltages could produce two effects: a small and temporary disturbance in flow which appeared to be electroosmotic in nature and direction: a sudden large surge of flow into the stem after prolonged electrical stimulation of up to 45,000 mv. The latter effect was called "flushing" and only occurred in young green stems which had previously been well exposed to sunlight. Artificial guttation was found to be associated with flushing.

ISSN:0008-4026    

DOI:10.1139/b62-041

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

A comparative study was made of the effect on the respiration of healthy andPuccinia reconditainfected leaf tips of Thatcher wheat of the application of 179 p.p.m. nickelous ion or 1000 p.p.m. sulphadiazine. Treatments were applied either 2, 3, or 4 days after inoculation. Both chemicals stopped the respiration and growth of the fungus on the second day after inoculation. Only nickel was effective on the third and fourth days, because the result of its action was permanent while that of the sulphadiazine was temporary.

ISSN:0008-4026    

DOI:10.1139/b62-042

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Multiply marked strains ofCochliobolus sativuswere used to synthesize heterokaryons. The heterokaryons apparently were formed by hyphal anastomosis and nuclear migration. Some conidia (not more than 6%) from heterokaryotic cultures perpetuated the heterokaryons. Probably this low frequency of heterokaryotic conidia was due to a non-random distribution of nuclei in the conidia. Variation in strains due to heterokaryosis may be reduced by the isolation of single spores or hyphal tips in several successive generations. Heterozygous diploids were selected from two heterokaryons on the basis of their phenotypic differences: heterokaryons grew slowly and intermittently; diploids grew rapidly and uniformly. Heterokaryons but not diploids readily dissociated into their components. Diploid spores were consistently larger but not twice as large in volume as haploid ones.Dominant–recessive relationships were expressed in heterokaryons and diploids; white was recessive to tan spore color; nutritional requirements were recessive to the wild type alleles; and resistance to anisomycin was semidominant. Segregants were obtained from a diploid strain by various techniques. Equal numbers of heterozygous and "presumptive" homozygous segregants were found and most of them were recombinants. A parasexual cycle therefore occurs in this heterothallic ascomycete.

ISSN:0008-4026    

DOI:10.1139/b62-043

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Conidia ofKabatiella caulivora(Kirch.) Karak. were observed to develop into various forms when cultured on different media. Conidial forms appeared to fall into four main categories with each form capable of producing typical conidia. These included (a) sickle-shaped, unicellular, hyaline conidia containing from 1–8 nuclei; (b) cylindrical to clavate, one- to two-celled hyaline conidia with 5–15 nuclei per cell; (c) multicellular, light to dark green conidia containing as many as 25 nuclei in the terminal cells; (d) cylindrical, two- to five-celled, dark brown, heavy-walled conidia containing 2–4 nuclei per cell. The above conidial forms have been observed in infected plant material.

ISSN:0008-4026    

DOI:10.1139/b62-044

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Podosporais the valid genus for a group of coprophilous species in which the ascospores have appendages but no gelatinous sheaths. The type species isP. fimicolaCesati. The following new species found on dung are described and illustrated:P. absimilis, Tautira;P. brasiliensis, Brazil;P. castorinospora, Panama Canal Zone;P. comatospora, Venezuela, Tautira, and Moorea;P. curvuloides, Brazil;P. inflatula, Tautira and Brazil;P. nannopodalis, New York;P. ostlingospora, Mexico;P. papilliformis, Venezuela and Mexico;P. prethopodalis, Tautira, Moorea, and Paea. The following are transferred fromPleurageas new combinations inPodospora:P. adelura(Griff.),P. anomala(Griff.),P. arizonensis(Griff.),P. collapsa(Griff.),P. gwynne-vaughaniae(Page),P. heterochaeta(Griff.),P. hyalopilosa(Stratton),P. immersa(Stratton),P. kansensis(Griff.),P. longicaudata(Griff.),P. taenioides(Griff.) andP. unicaudata(C. & M. Moreau). The following are transferred fromSordariaas new combinations inPodospora:P. araneosa(Cain),P. cervina(Cain),P. coronifera(Grove),P. curvispora(Cain),P. dubia(Hansen),P. eminens(Cain),P. fimbriate, (Bayer),P. globosa(Massee & Salmon),P. glutinans(Cain),P. inaequalis(Cain),P. inaequilateralis(Cain),P. kilimandscharica(A. Schmidt),P. leporina(Cain),P. linguiformis(Cain),P. ontariensis(Cain),P. perplexens(Cain),P. pilosa(Mouton),P. piriformis(Bayer),P. tetraspora(Winter). The following are transferred fromPhilocopraas new combinations inPodospora:P. coeruleotecta(Rehm) andP. millespora(A. Schmidt).

ISSN:0008-4026    

DOI:10.1139/b62-045

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Large stands ofEuphorbia cyparissiasL. in Ontario supporting aecia ofUromyces striatusSchroet. presented an opportunity for the author to study this stage of the rust hitherto little known in North America since its discovery here in 1947. The mycelium was found to be systemic and perennial and the aeciospores capable of infecting many species ofMedicagoand some yellow-flowered species ofTrifolium. Pisum sativumwas just slightly susceptible. Both diploid and tetraploid nuclear conditions ofE. cyparissiashave been found rusted andE. esula, long suspected as a host in Europe, has also been found rusted and the connection to Leguminosae shown by inoculation. Specimens resulting from inoculations (109) and from field collections from Canada (33), United States (18), and Europe (13) were identical in spore morphology. This, plus susceptibility of Leguminosae from Europe to the inoculum from Ontario, supports the suggestion that the rust was introduced to North America from Europe. It is further suggested thatU. striatuswas introduced on either or both alternate hosts independently. The common occurrence of telia is recorded and the fungus is redescribed.

ISSN:0008-4026    

DOI:10.1139/b62-046

出版商:NRC Research Press    

年代:1962

数据来源: NRC