摘要:

The perfect stage of a flax strain ofRhizoctonia solaniKühn was obtained fairly consistently on artificial media. In growth characters and morphological dimensions, it agreed closely with those ofPellicularia filamentosa(Pat.) Rogers, except that its sterigmata averaged three times as long (26 μ). This latter character suggests close relationship toCorticium praticolaKotila. Single-basidiospore cultures differed among themselves and from the parent strain in morphology, cultural characters, growth rates, and pathogenicity on Royal flax. Some single-spore cultures produced the perfect stage, although preliminary pairings of sterile single-spore cultures remained sterile. This isolate is thus heterozygous and homothallic. There appear to be 12 chromosomes in the diploid nucleus in the basidium. The mature basidiospore is predominantly uninucleate; occasionally a binucleate basidiospore is observed. Germination is by repetition on plain agar, or by germ tubes on rich media. Those basidiospores which germinate by repetition are commonly uninucleate and give rise to uninucleate secondary basidiospores. Basidiospore discharge is by the drop excretion mechanism. To determine the identity of the flax strain, it will be necessary to produce the perfect stage of the flax strain on natural substrates or the perfect stage ofP.filamentosaon artificial media.

ISSN:0008-4026    

DOI:10.1139/b53-051

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Each flagellum ofChlamydomonas moewusiiappears to originate at a basal granule beneath the papilla. The intact flagellum is composed of:(a) a central axis, consisting of 9 – 11 dense fibrils, 450 Å wide, fused laterally to form a hollow cylinder;(b) a less dense component, possibly fluid, within the axial cylinder; and(c) a sheath of less dense material, surrounding the axial cylinder, and clearly delimited by a superficial membrane which is believed to be semipermeable. Mating-type specificity seems to reside in this component, since it is involved in the agglutination reaction which precedes copulation.The flagellum terminates in a mucro 0.3 – 0.5 μ long. There is no whiplash filament. Certain structural changes, due to disorganization, disruption, or disintegration of the flagellar components, are described and figured. Possible modes of action of the flagella in cell propulsion are briefly discussed in the light of flagellar structure as revealed by electron microscopy. No structural differences have been observed between the flagella of paralyzed mutants and of wild-type cells.

ISSN:0008-4026    

DOI:10.1139/b53-052

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A slide technique suitable for studying the behavior of fungi and actinomycetes both qualitatively and quantitatively in soil is described. BesidesHelminthosporium sativum, eight other fungi and one actinomycete were used to demonstrate the applicability of the method which was used for both natural and soybean meal amended soils. In the natural soil spores ofPenicillium notatum,Stachybotrys atra, and the actinomycete only germinated. However, lysis or disintegration of the germ tubes of the two fungi was observed on the fourth day. Growth of the actinomycete was continuous to at least the seventh day. In the amended soil only one fungus failed to germinate. Of those that germinated, onlyFusarium culmorumand the actinomycete were capable of continued growth and sporulation. Lysis or disintegration of the germ tubes of the others was noticed on the fourth day.

ISSN:0008-4026    

DOI:10.1139/b53-053

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A phage specific for one isolate ofXanthomonas translucensf. sp.undulosaand three polyvirulent phages active against various members of theX.translucensgroup have been isolated. One of the polyvirulent phages, Pg35, lysed 24 out of 28 isolates ofX.translucens; the other two were somewhat less active. Attempts to use form specific phages to identify cultures ofX.translucensf. spp.hordei,hordei-avenae, andundulosawere unsuccessful. However, use of a phage specific for f. sp.secalisto detect homologous cultures gave encouraging results.

ISSN:0008-4026    

DOI:10.1139/b53-054

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The physiological characteristics and host plant relationships of 14 strains of rhizobia, isolated from the nodules ofCaragana arborescensL., have been studied. The nodules from which these isolates were obtained came from six widely separated localities in North America. The strains differed markedly in rates of growth, in their ability to reduce nitrate, in their reactions in litmus milk and on 12 carbohydrate media, and in their abilities to fix nitrogen symbiotically. The strains showed uniformity in their abilities to produce nodules onPhaseolus vulgaris,Colutea arborescens,Lespedeza stipulacea,Trifolium pratense, andLotus corniculatus. Because these species are now included in separate bacterial–plant groups, an assignment ofC.arborescensto a cross-inoculation group appears unwise at this time. Thirty strains of rhizobia isolated from 20 species contained in 15 leguminous genera failed to nodulateC.arborescensin greenhouse tests. Various examples of nonreciprocal cross-inoculation were noted. Strains of caragana rhizobia reisolated from nodules formed by them onTrifolium pratenseandColutea arborescensretained their abilities to form nodules onCaragana arborescens.

ISSN:0008-4026    

DOI:10.1139/b53-055

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Foliage infection of pea byAscochyta pisiLib. is accomplished by direct penetration of the cuticle without the formation of an appressorium. Subsequent colonization is at first subcuticular, then intercellular, resulting in the collapse and death of the host cells. No haustoria are formed. Resistance may be due in part to the cuticular barrier as well as to a physiologic factor which limits the colonization of the host once penetration has been effected. Pycnidial formation is symphogenous. Spores are produced singly from conidiophores that grow out from the inner wall cells of the pycnidium. Each spore is two-celled, and each cell contains but one nucleus. A single nuclear division occurs early in the ontogeny of the spore so that most spores even prior to germination have binucleate cells. Spore production is marked by the almost complete depletion of the protoplasmic content of the fungal mass; as a consequence vegetative development of the mycelium ceases and the focus of infection becomes localized as a leaf spot. It is suggested that the production of this discrete type of lesion byA.pisiand certain other pycnidiaceous leaf-spotting fungi is, mainly, a function of the developmental rhythm of the fungus, and, accordingly, is not the expression of a specific host-parasite interaction.

ISSN:0008-4026    

DOI:10.1139/b53-056

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

It has been found by cultural methods thatOdontia bicolor(Alb. & Schw. ex Fries) Bres. is the cause of an important butt rot in various species of coniferous and broad-leaved trees in Canada. A description of the cultural characters of the fungus and the decay from which it has been isolated is presented.

ISSN:0008-4026    

DOI:10.1139/b53-057

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

On the basis of a sample of 24 fruit bodies ofPolyporus obtususBerk. collected at Chalk River, Ont., in which there were found to be 39 alleles at each of the loci for heterothallism, it was estimated that the number of alleles at each of these loci in the local concentration, of the fungus occurring there is 112. This agrees closely with previous estimates of the total number of alleles at these loci for the Hymenomycetes in general, and is interpreted as evidence that the local concentration of the fungus at Chalk River is not an isolated occurrence as hitherto supposed. This view is further supported by collections of the fungus in several widely scattered areas in Ontario since the initiation of this study.

ISSN:0008-4026    

DOI:10.1139/b53-058

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

In this study, species ofPeniophorawhich appear to belong in the subsection*** of Bourdot and Galzin's sectionTubuliferaeare segregated on the basis of a single cystidial characteristic, namely: the solubility in 10% potassium hydroxide of thickened cystidial walls. Complete descriptions are given of six previously described species (P.accedens,P.calothrix,P.chaetophora,P.crassa,P.juniperina,P.vermifera) and two species proposed as new (P.angusta,P.sceptrifera). Also included in a provisional key are four species recently described in this series of studies (P.hamata,P.inornata,P.prominens,P.regifica), as well as three long-known species (P.gracillima,P.hirtella,P.subulata). This work is presented as introductory to a taxonomic reconsideration of theTubuliferaesection of the genusPeniophora.

ISSN:0008-4026    

DOI:10.1139/b53-059

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

In a previous paper, the species of the genusChaetomiumpossessing dichotomously branched terminal hairs were described and figured. In the present report the remaining species of the genus are considered with special emphasis on the species isolated from seeds. Of a total of 47 recognized species, 16 have been found inhabiting seeds; one of these,C.atrosporumis described as new. Type collections of many of the species have been examined and descriptions and illustrations of these are included, along with a key to the recognized species.

ISSN:0008-4026    

DOI:10.1139/b53-060

出版商:NRC Research Press    

年代:1953

数据来源: NRC