摘要:

When14C-labelled 2,4-D [(2,4-dichlorophenoxy)acetic acid] was applied to the basal leaves of Canada thistle (Cirsium arvenseL.), prior removal of approximately the upper two-thirds of the flowering shoot resulted in a 20 to 30% increase in total14C exported from the treated leaves and a twofold to threefold increase in the amount in the roots. Removing only the apical region of the shoot had the opposite effect, markedly reducing14C export from the treated leaves and translocation to the roots. Provision of a higher N level more than doubled14C translocation from the treated leaves and caused a threefold increase in14C content of the roots of undecapitated plants. The reduction in basipetal transport produced by apical decapitation was attributed to the inhibiting influence of subapical lateral shoots on basal branching and root bud growth. When apical decapitation was combined with removal of the axillary buds in the subapical region, basal branching and root bud growth were promoted and14C translocation into the roots was significantly increased.

ISSN:0008-4026    

DOI:10.1139/b78-078

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Hybridization of gametes produced by different teliospores ofUstilago nuda(Jens) Rostr. was demonstrated to occur within the host. Confirmation that a host plant is usually infected by only a single dikaryon permitted the sampling of sori as presumptive hybrids. The detection of hybrids relied upon the use of two strains of smut that differed in teliospore color and virulence on a range of host cultivars. The potential for hybridization was calculated to be as much as 43% of the amount expected from random mating between the gametes produced by teliospores in the florets of barley.

ISSN:0008-4026    

DOI:10.1139/b78-079

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Pycnidia ofPhomopsis juniperovoraonJuniperus virginianawere examined for occurrence of beta spores. Beta spores were observed in only 3% of the pycnidia on diseased material collected in the field. The most beta spores observed in one pycnidium was four. Thirty-two percent of the pycnidia produced after diseased material was collected contained beta spores. The beta spore content in induced pycnidia ranged from 0 to 85% of the spores observed. The pycnidia observed from cultures on potato dextrose agar contained between 15 and 98% beta spores. The absence of beta spores in pycnidia on field-collected material hinders proper diagnosis of the causal organism.

ISSN:0008-4026    

DOI:10.1139/b78-080

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A dematiaceous Hyphomycete collected onIxoraleaf litter from India is described. The fungus produces two types of conidia: lenticular and selenoid, both typically bivalved with a germ slit, blastic, solitary, terminal on the conidiophore and its successive sympodial proliferations. It is conspecific with the Tanzanian collection of a fungus assigned by Pirozynski in 1972 toRhinocladiella critasporaMatsushima and designated the holotype of a new species ofPseudobeltrania, P. selenoides, by de Hoog in 1977.Pseudobeltrania selenoidesis made the type of a new genusArdhachandra;Rhinocladiella critasporaMatsushima (=Pseudobeltrania critaspora(Matsushima) de Hoog) is transferred toArdhachandraasA. critaspora(Matsushima) comb. nov.

ISSN:0008-4026    

DOI:10.1139/b78-081

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Cyathus pedicellatussp.nov. (Nidulariaceae) is a large, dark brown, deeply plicate species readily distinguished from all others because the cupulate portion of the peridium is attached to the emplacement by a conspicuous dark-coloured pedicel of firm texture. ThisCyathusfrom Colombia is closely related taxonomically toC. limbatusTul.

ISSN:0008-4026    

DOI:10.1139/b78-082

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

In vitroPuccinia graminisf.sp.tritici, race 32, produced dikaryotic hyphae from infection structures, corresponding to appressoria and substomatal vesicles (differentiated), which are formed by germ tubes as a response to a heat shock within 24 h after seeding the spores. Dikaryotic hyphae also formed spontaneously from nondifferentiated senescing germ tubes 3–4 days after seeding the spores. The hyphae which originated from the different structures did not appear to be different with regard to nuclear condition, morphological appearance, and fluorescence properties as a consequence of Feulgen staining. 3,3′-Bis-indolylmethane (BIM) increased the hyphal growth rate in contrast with the germ tube growth rate. It also supported the transition from germ tube growth to hyphal growth. The possible mode of action of BIM and the involvement of an unknown factor which represses hyphal growth are discussed.

ISSN:0008-4026    

DOI:10.1139/b78-083

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Macropycnidiospores and pycnidia ofSeptoria triticiin leaves of naturally infected Cheyenne and Minter winter wheats decreased in size as the growing season progressed. The change in the size of the spores and pycnidia was negatively correlated with days after planting and increased leaf necrosis. In glasshouse experiments, the size of spores and pycnidia was not significantly affected by changes in the percentage of the leaf area that was covered by lesions bearing pycnidia, vernalization, or the isolate ofS. tritici. Spores and pycnidia were significantly larger at 18 °C than at 27 °C in Era spring wheat but not in Minter winter wheat. In both Era and Minter, the spores that formed in infected leaves with dry surfaces were smaller than those that formed in leaves with wet surfaces, although the differences were not significant. Pycnidia in leaves of Era that were kept dry were significantly larger than those in leaves that were kept wet, but wet leaves senesced rapidly.

ISSN:0008-4026    

DOI:10.1139/b78-084

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Using results obtained with light and scanning electron microscopy of critical-point-dried material and transmission electron microscopy of carbon replicas and freeze-fracture and ultra-thin sections, the structure and germination of the sporangiospore ofPhascolomyces articulosusBoedijn is described. The sporangial wall is trilaminate and the ornamented spore wall is two layered. During germination, a new wall layer develops between the plasmalemma and the original spore wall. Sporangial structure is related to that of other members of the Thamnidiaceae and the use of germinating spores ofP. articulosusfor infection studies of the mycoparasitePiptocephalis unisporais indicated.

ISSN:0008-4026    

DOI:10.1139/b78-085

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Meiotic nuclear behavior and chromosome numbers have been examined, using a propionic–iron–hematoxylin staining method, inNeurospora crassaand in five homothallic species,N. africana, N. dodgei, N. galapagosensis, N. lineolataandN. tcrricola. Ascus development, haploid chromosome numbers (n = 7), and morphology in all five homothallic species resemble the heterothallicN. crassa. The following observations have not been reported previously for anyNeurosporaspecies, although some have been described in other fungi. Most observations apply to all five homothallic species and toN. crassaexcept where otherwise indicated. (1) Chromosomes elongate considerably between karyogamy and the beginning of synapsis, and leptotene and zygotene stages can be identified. (2) The ascus tip flattens, and an apical pore begins to form during diplotene. (3) After telophase III, when all eight nuclei line up in single file, the nuclei are always arranged perpendicularly to the ascus wall with all spindle plaques on the same side. All nuclei then tilt relative to the ascus base with the spindle plaques at the lower end; consequently, the spores become obliquely arranged. (4) Ascospores ofN. terricolaare initially spindle shaped and occupy the entire ascus but later become compact and ovoid with spaces between them. (5) Maturing ascospores grow two to four times their initial compacted size. (6) In the young ascus, the nucleolus usually orients toward the base. (7) InN. terricola, the nucleolus is frequently hemispherical, especially in the young asci. (8) Half-moon-shaped polar caps are sometimes visible, one on each side of the prophase I nucleus; these are most prominent inN. terricola. (9) Cytological preparations are greatly improved if hydrolyzed perithecia are thoroughly washed in a Carnoy's solution containing chloroform.

ISSN:0008-4026    

DOI:10.1139/b78-086

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The effect of ferulic acid upon phosphate absorption by excised and intact roots of three soybean (Glycine max(L.) Merrill) varieties (Hill, Ogden, and Jackson) was examined using32P-labelled solutions. Kinetic analysis of the phosphate uptake rates of roots of 3-day-old seedlings showed that 0.5 and 1.0 mMferulic acid inhibited the absorption of phosphate by each variety. This inhibition was noncompetitive; the presence of ferulic acid reduced theVmaxvalues of the absorption systems but did not alter the values of the apparentKm. No direct effect upon the translocation of absorbed phosphate was found in the intact seedlings.

ISSN:0008-4026    

DOI:10.1139/b78-087

出版商:NRC Research Press    

年代:1978

数据来源: NRC