摘要:

The asci ofHerpomycessp. (Laboulbeniales) compose a parenchymatous tissue produced by progressive cleavage of three or four meristematic ascogenous cells attached in the base of the ascocarp. Ascospores are delimited by membranes derived from an ascus vesicle, and the spore wall forms between paired prospore membranes. Dilated cisternae and epiplasmic membranes are associated with wall formation. While ascospores are developing, asci are displaced apically, their passage apparently lubricated by a matrix secreted by the peridial cells.The presence of an ascomycetous spindle pole body, septal pore with Woronin bodies, ascus vesicle, and dilated Golgi-like cisternae indicates a close relationship betweenHerpomycessp. and the filamentous Ascomycetes while providing no support for theories maintaining a close relationship between Laboulbeniales and the red algae.

ISSN:0008-4026    

DOI:10.1139/b77-228

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) seedlings were grown outdoors under 9, 44, and 100% light intensity and were sampled periodically over their first growing season for stem, leaf, and root dry weights, and the data were analyzed allometrically. In addition, seedlings were assessed for number of needles per stem length, ratio leaf surface area: leaf dry weight, and maximum seedling dry weight. The experiment was repeated during a 2nd, warmer, year.Maximum growth occurred under partial shade and moderate temperatures. In the 1st year, seedlings allocated progressively more dry matter to shoot than to root growth as light intensity decreased. In the 2nd year, root growth was favored at the expense of shoot growth. In both years, shoot structural alterations were such as to favor enhanced photosynthesis under low light. Acclimative changes are explained in terms of an interaction between light, temperature, and seedling size.A second experiment showed that seedlings grown under low light set a terminal bud sooner in the fall and broke bud sooner the next spring than seedlings preconditioned to high light. They also suffered more spring frost damage and showed greater incidence of lammas growth in the 2nd year. No effect of 1st-year preconditioning on timing of budbreak was evident in the 3rd year.

ISSN:0008-4026    

DOI:10.1139/b77-229

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Isolates ofPseudomonas syringaefrom hairy vetch were either virulent (compatible) or avirulent (incompatible) to bean. When bean pods were injected at high inoculum levels (5 × 107 cells/ml), both compatible and incompatible isolates multiplied rapidly and caused water-soaking of injected tissues; populations of both isolates were similar at the end of log phase. Lesions caused by the incompatible isolate turned brown by 3 days after inoculation and did not expand; those caused by the compatible isolate remained water-soaked and expanded into the adjoining, noninoculated tissues. At low inoculum levels (5 × 104 cells/ml), the compatible isolate exhibited the same pattern of multiplication and lesion development as at the high inoculum level. The incompatible isolate, on the other hand, caused necrotic flecking within the injected area by 24 h, and these small lesions remained limited. Appearance of the necrotic flecks was correlated with a progressive decline in bacterial populations; after5 days, the population of incompatible bacteria was about a hundredfold lower than that of compatible ones. Populations of incompatible bacteria within and between the necrotic flecks declined rapidly, indicating the potential accumulation of inhibitors of bacterial growth as a result of an inducible resistance mechanism.The phytoalexin phaseollin reached 280 μg/g fresh weight by 3 days after inoculation of bean pods with incompatible bacteria. However, this compound was not involved in resistance. Neither compatible nor incompatible isolates of the bacterium were significantly inhibited when grown in a medium saturated with phaseollin. When other antibiotic substances in plant extracts were sought, substantial amounts of inhibitory compounds were detected only in the ethanolic extract (fraction soluble in ethyl acetate) of pods previously inoculated with an incompatible isolate ofP. syringae. Only low levels of inhibition were obtained from identical extracts of uninfected pods or from pods inoculated with a compatible isolate ofP. syringae. Bacterial growth was completely prevented in a bean infusion medium containing 1 g fresh weight equivalent of pod tissue challenged with the incompatible isolate. The active compound(s) was nonfluorescent, had a UV absorption maximum at 286 nm, and gave a positive reaction with reagents for phenolic compounds.

ISSN:0008-4026    

DOI:10.1139/b77-230

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Birefringence, energy-dispersive x-ray analysis (EDX), and ultrastructural studies were performed on control and on extracted carposporic and tetrasporicChondrus crispusStack. thalli.EDX analysis of untreated carposporic and tetrasporic plants revealed the presence of sulphur primarily in the intercellular matrix and cell walls. The sulphur levels detected were greater in tetrasporic than in carposporic plants. EDX analysis of tetrasporic and carposporic plants after extraction with hot aqueous bicarbonate, which should remove most of the sulphated polysaccharide carrageenan, showed little sulphur in walls and intercellular matrices.The microfibrils visible with transmission electron microscopy in cell walls of both generations ofC. crispusappeared to run parallel to the cell surface, i.e. circumferentially. Some areas of the intercellular matrix were entirely granular, while others contained microfibrils. After extraction, microfibrils in cell walls and intercellular matrix were disorganized but were still present, perhaps in reduced amounts.The birefringence which characterized the walls of untreated cells was greatly reduced by 2 h extraction, and matrix birefringence was entirely removed. Cortical cell walls could still be identified and stained metachromatically with toluidine blue, but they were no longer birefringent. Further extraction (5 h) removed residual birefringence, but rhizoid cell walls were still metachromatic, as were the remnants of small cells believed to be cortical in origin.

ISSN:0008-4026    

DOI:10.1139/b77-231

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Eleven [14C]-labeled amino acids were tested for their ability to serve as precursors of HCN in cultures of a psychrophilic basidiomycete. Only glycine and, to a much lesser degree,L-serine andL-aspartic acid were effective. By using [2-14C,15N]glycine, it was demonstrated that the C–N bond remains intact during the conversion to HCN. No evidence was obtained for the participation ofN-hydroxyglycine or glyoxylic acid oxime as intermediates in the pathway of HCN formation.

ISSN:0008-4026    

DOI:10.1139/b77-232

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Plectritis brachystemonis polymorphic for plants with winged or wingless fruits. The polymorphism is controlled by a single locus with the allele for winged fruits exhibiting complete dominance. Using this locus as a genetic marker, progeny tests of natural populations gave estimated outcrossing rates of 0 to 3.33%. Heterozygotes were infrequent in the populations sampled. Populations fixed for one allele or the other at the winged-fruit locus are common inP. brachystemonbut are rare in the related outcrossing speciesP. congesta.

ISSN:0008-4026    

DOI:10.1139/b77-233

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The occurrence of crystals of calcium oxalate increases with increasing growth rate of the Virginia creeper (Parthenocissus tricuspidataPlanchon). They are not an end product of metabolism but can partly reenter in the metabolism especially when buds start in the spring. Radioactivity from [14C]oxalate suppliedin situis recovered in glycolate, glycine, serine, and glycerate, all intermediates of the glycolate pathway, whereas a small fraction is evolved as photorespiratory CO2.

ISSN:0008-4026    

DOI:10.1139/b77-234

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The nameBelliaBroth. (1907, Hookeriaceae) is a later homonym ofBelliaBubani (1899, Umbelliferae) and the nameCrosbyais proposed as a replacement for the moss name. A taxonomic and numerical treatment of this genus shows thatCrosbya nervosa(Hook. f. & Tayl.) Vitt andCrosbya straminea(Mitt.exBeck.) Vitt are separate species. A polygraphic analysis indicates that the two species are morphologically distinct.Crosbya nervosais endemic to the northern portion of the Auckland Islands and Campbell Island, whereasC. stramineais endemic to New Zealand.

ISSN:0008-4026    

DOI:10.1139/b77-235

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Myriogenospora atramentosa(Berk & Curt.) Diehl has been found on species ofPaspalum, Andropogon, Eragrostis, andPanicumin surveys of pastures with histories of toxicity problems in cattle. The fungus produces a systemic infection in which growth on the host is entirely superficial. Infection of each leaf and inflorescence occurs from mycelium in the bud. In the upper part of the leaf one side of the blade remains unexpanded and is bound into a tight roll by a mass of fungus plectenchyma that it encloses. Branches of the inflorescence are enmeshed in a fungus matrix and remain enclosed within the flag leaf sheath. Superficial, linear, black stromata form down the middle of the leaf alongside the leaf roll and in the juncture between margins of the flag leaf sheath. The stromata produce fusoid conidia in a fleeting early stage. Immersed perithecia develop in a longitudinal row in the stroma. The cluster of aparaphysate asci on a basal cushion, lateral paraphyses, and indistinct peridia of the perithecia are characteristic of the Clavicipitaceae. The numerous fusoid spores in the swollen asci are part-spores derived from fragmentation of eight filiform, septate ascospores. The refractive cap at the apex of the ascus is a modification of the typical clavicipitaceous structure.Myriogenosporais placed in the tribe Balansiae of the Clavicipitaceae.

ISSN:0008-4026    

DOI:10.1139/b77-236

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Blade meristems ofAlaria esculenta(L.) Grev. (Laminariales, Phaeophyta) were treated with growth-inhibiting concentrations (10−3 M) of auxins and chemically related non-auxins, e.g., 2,4- and 3,5-dichlorophenoxyacetic acids, respectively. Photosynthesis was inhibited with increasing effectiveness by both auxins and non-auxins in the following classes: naphthaleneacetic < naphthoxyacetic <phenoxyacetic acids. Inhibition was reversed by transferring sections to fresh seawater from naphthaleneacetic and naphthoxyacetic acids. Chloroplast swelling, observed in electron micrographs of lateral portions ofAlariablade meristems, was positively correlated with the degree of inhibition of photosynthesis. The ratio of14C incorporation into mannitol and amino acid fractions of alcohol-soluble organic matter was also modified by the inhibitors, especially phenoxyacetic acids.A 50% increase in photosynthetic rate of the blade meristem occurs within 24 h of its excision from theAlariafrond.

ISSN:0008-4026    

DOI:10.1139/b77-237

出版商:NRC Research Press    

年代:1977

数据来源: NRC