摘要:

Eggs, sperm, zygotes, and embryos ofFucus serratusL. fixed14CO2in light. Based on a visual estimation of sample size, eggs had a somewhat higher rate of photosynthesis than sperm. The rate for eggs declined with time but increased on fertilization. The rate of photosynthesis in embryos increased rapidly during the first days of their growth. Eggs and particularly sperm tended to produce more amino acids than embryos, whose products of photosynthesis were similar to those found in mature plants.

ISSN:0008-4026    

DOI:10.1139/b78-045

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Synopses of genera of Triticeae (includingElymus triniiwhich is not classified within any genus here) were elaborated and are here documented. A generic classificatory key together with four auxiliary keys are also provided: these are not analytical keys normally found in most treatments whose purpose is to identify every case to taxon. The synopses and keys were generated by computer using Pankhurst's program for generating diagnostic keys. Canonical analyses were performed on the six groupings obtained previously from a numerical taxonomic classification of the genera of this tribe. Canonical loadings, to be used for placement of the OTUs and graphic separation of the groupings, are provided. This paper does not treat the multitude of natural and artificial hybrids.

ISSN:0008-4026    

DOI:10.1139/b78-046

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Seven lines of rye (Secale cerealeL.), six inbred (S9) and one open-pollinated, were used as pollen parents in crosses with two tetraploid wheat strains (Triticum turgidumvar. durum cvs. 'Jori' and 'Langdon'). The rye lines were of diverse genetic background and exhibited significant differences in meiotic stability as measured by frequencies of chiasmata and univalent formation. The rate and extent of development of the embryo and endosperm tissue of hybrid ovules were not influenced by the level of meiotic stability of the rye parent, but rather by a genetic interaction between a specific rye genotype and wheat. This was indicated by the significant differences obtained in the frequency of normal embryo formation when different rye lines were used as parents in crosses to a common wheat cultivar. The specific effect of the wheat genotype on the mean seedset was shown by the significant differences obtained when different wheat cultivars were crossed with a given set of rye genotypes under the same environmental conditions. The prevailing ambient temperature significantly affected hybrid embryo and endosperm development in vivo.

ISSN:0008-4026    

DOI:10.1139/b78-047

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Pure cultures of the very rare entomogenous ascomyceteCordyceps memorabilisCesati, derived from both endosclerotia and ascospores, have shown that the conidial state of this fungus isPaecilomyces farinosus(Holm ex S. F. Gray) Brown & Smith. Coremia ofP. farinosuswere produced in culture, but the perithecia of the sexual state have not yet been obtained under artificial conditions.

ISSN:0008-4026    

DOI:10.1139/b78-048

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Spermatium formation inPuccinia coronata avenaewas concluded to be annellidic but with some phialidic analogies. The spermatiophore wall consisted of a prominent outer layer and a very thin inner layer. During formation of the first spermatium initial, the apical end of the spermatiophore became somewhat swollen and a septum was then formed centripetally at the base of the swelling to delimit the primary spermatium. The wall layers of the first spermatium were derived from the wall layers of the spermatiophore. The mature septum consisted of two bilayered walls separated by a clear septal lamella. The upper septal wall formed the basal wall portion of the preceding spermatium and the lower septal wall became the distal wall portion of the succeeding spermatium. The layers of each septal wall were confluent with the inner and outer periclinal wall layers of the developing spermatia. After spermatium secession, the broken outer wall layer left remnants as a basal frill on the spermatium and an annular scar on the spermatiophore. Each succeeding spermatium formed at a near-fixed locus on the spermatiophore. Although the formation of succeeding spermatia appeared superficially to be phialidic, examination of wall relationships indicated that the formation of each successive spermatium recapitulated the holoblastic first spermatium.As the spermatia matured, the outer wall layer, including the basal frill, gradually dissipated. The thickness of the spermatium wall was maintained by expansion of the inner layer. In mature spermatia, the inner layer comprised the bulk of the wall, and the outer layer was left as a thin tenuous band surrounding the spermatium.

ISSN:0008-4026    

DOI:10.1139/b78-049

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Preparations of phosphoenolpyruvate (PEP) carboxylase activity fromAvenu sativacoleoptile tissue were assayed by measuring the incorporation of labelled bicarbonate into a derivative of oxaloacetic acid or by coupling oxaloacetic acid production to malate dehydrogenase activity and the oxidation of NADH. Malate inhibition of PEP carboxylase activity was found to be noncompetitive, was not due to a mass action effect on the coupled enzyme system or to chelation of Mg2+, and probably involved direct inhibition of the enzyme by malate. Maximal PEP carboxylase activity was exhibited around pH 8.0 and increased 125% between pH 7.0 and pH 7.6. Inhibition by 4 mML-malate was virtually complete at pH 7.0 and decreased to 10% inhibition at pH 8. This information is discussed in the light of data which demonstrates that in response to IAA. coleoptile tissue accumulates malate and secretes H+. The regulatory properties of PEP carboxylase are consistent with a role in malate production which could resist increases in intracellular pH resulting from an auxin-stimulated H+efflux.

ISSN:0008-4026    

DOI:10.1139/b78-050

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Cells ofC. crypticabecome plasmolyzed when subjected to a sudden increase in extracellular osmotic pressure (0.3 to 1.01 osmol/kg). Protoplasts regain their original volume if certain ionic species are present in the plasmolyzing solution. KCl is most important since it is the only electrolyte which allows deplasmolysis when supplied alone, and cells do not deplasmolyze if KCl is omitted. Ca2+, Mg2+, and Na+are also necessary for high rates of deplasmolysis. Neither light nor ouabain have any effect on deplasmolysis rate in contrast with 2,4-dinitrophenol, which acts as a reversible inhibitor. The characteristics of deplasmolysis are consistent with a mechanism based on energy-dependent uptake of KCl, which is also affected by Na+and divalent cations.Earlier workers in the field of permeability studies added sucrose to diatom suspensions in ion-containing media and observed plasmolysis followed by rapid deplasmolysis. This was interpreted as evidence for unusually high permeability to sucrose. The present work indicates that diatoms are impermeable to sucrose and that deplasmolysis observed by earlier workers was due to active uptake of ions rather than high permeability to sucrose. It is demonstrated that this technique can also be used for comparative studies of osmoregulation.

ISSN:0008-4026    

DOI:10.1139/b78-051

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The partitioning of dry matter into component plant parts has been traced for four legumes. The four species were chosen to represent different positions along ther-K continuum. Three of the species,Medicago lupulina, M. sativa, andTrifolium pratense, behaved essentially as predicted byr- and K-selection theory. However, the stolons ofT. repensare formed within 7 weeks of germination and thus permit this species to reproduce sooner thanMedicago lupulinacan reproduce by seed. In this way,T. repenscan behave as anrstrategist in an environment imposing density-dependent regulation (a ‘K' type environment).

ISSN:0008-4026    

DOI:10.1139/b78-052

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A seasonal study of accumulation of calcium, magnesium, sodium, potassium, and phosphorus was made onPontederia cordataL., an important component of wetlands in North America. Twice weekly sampling of soil and plant material was made from May 23, 1975, to September 23, 1975. Results were analysed using the prepared program POLYFIT TSL, which fits a curve to the data and prepares anR2value (coefficient of multiple determination) for the data. Positive correlations between seasonal growth events ofP. cordataand accumulation of individual ions were obtained from the analysis. In addition, a positive correlation between accumulation of ions and changes of ion concentration in the upper horizon of the soil was detected for potassium and magnesium.

ISSN:0008-4026    

DOI:10.1139/b78-053

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Spore release was observed in eight decay fungi of southern hardwood near Stoneville, Mississippi. During June–September, daily spore release peaks ofIrpex mollis, Fomes geotropus, F. rimosus, andPolyporus lucidusoccurred in evening and those ofF. everhartiiandP. fissilisoccurred at night. Means were 17–30 °C and 60% RH or higher during peaks. Afternoon peaks were also recorded forP. fissilis, P. sulphureus, andP. dryadeusfrom November to February when daily temperature was high (means = 10–16 °C) and RH decreased (means = 63–76%). Phenological data indicate that temperature is the most important periodic stimulus.

ISSN:0008-4026    

DOI:10.1139/b78-054

出版商:NRC Research Press    

年代:1978

数据来源: NRC