摘要:

A naturally occurring glycoprotein present inBoerhaavia diffusaroot extract (BD inhibitor), causes plant cells to produce a highly active antiviral agent (AVA) that defends cells against infection by viruses. AVA was present in inhibitor-treated plants only, but not in nontreated plants, and was produced 2–48 h after treatment with BD inhibitor. AVA was effective not only in plant species in which it was produced but in other plant species as well. Crude AVA was active bothin vitroandin vivo. In vitro, it markedly reduced the infectivity of viruses, andin vivo, the virus content in AVA-treated leaves and leaf discs was considerably suppressed. The AVA showed the characteristics of protein.

ISSN:0008-4026    

DOI:10.1139/b80-246

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

One moss taxon and five lichen taxa new to British Columbia and eight moss taxa new to the Yukon are reported. In addition, four other rare British Columbia or Yukon species are discussed.

ISSN:0008-4026    

DOI:10.1139/b80-247

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Alpine lichen-dominated vegetation is described with emphasis upon floristic composition, quantitative structure, and distribution of lichen communities. Macrolichens and vascular plants were quantitatively sampled using stratified random quadrats (10 cm × 40 cm) in 40 stands (30 m × 5 m) in west-central Alberta and north central Yukon Territory. Comparable acid and basic substrates, and glaciated and unglaciated sites were sampled in each region. Bray-Curtis and reciprocal averaging ordinations were used to analyze vegetation data. For both macrolichens and vascular plants, floristic similarity is greater within each region than on equivalent substrates in different regions. Three alpine macrolichen communities are described in each region which exhibit pronounced regional differences.Cetraria tilesiiandThamnolia subuliformischaracterize driest sites in both regions, whileCetraria cucullataindicates mesic habitats.Cladoniaspp. dominate acidic Yukon sites;Stereocaulon alpinumandPeltigera aphthosacharacterize equivalent Alberta habitats. Vascular plant communities are dominated byDryas integrifoliaandD. octopetalain Alberta and Yukon areas, respectively, with dwarf willow and heath in acidic, mesic sites. Distribution of alpine communities of macrolichens and corresponding vascular plants is more strongly correlated with substate pH and moisture, than with glaciation history. Comparison with other northern studies suggests that these macrolichen communities may be found throughout the Canadian Cordillera where equivalent habitats are present.

ISSN:0008-4026    

DOI:10.1139/b80-248

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The levels and developmental patterns of the two acid phosphatases in the two strains ofIpomoeasp. (morning glory) grown in vitro are influenced differently by gibberellic acid (GA3). In the strain that requires a number of exogenously added hormones for growth (original strain), GA3appears to show little effect on the specific activity of the phosphatases during the initial 3 days of growth but represses their levels in the growth medium, soluble and particulate fractions upon further growth. The repressive effect of both inorganic phosphate and GA3on the enzymes appears to be additive. In the strain that does not require exogenously added hormones for growth (NH strain), the level of enzymes in the soluble fraction increases in the presence of GA3during the early stages of growth and then decreases with culture age. GA3also elevates the level of the enzymes in the particulate fraction over that in the controls. This elevation increases as phosphate level in the medium is increased. However, GA3greatly decreases secretion, or leaching of the enzymes from the cells.

ISSN:0008-4026    

DOI:10.1139/b80-249

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Young, greenhouse-grown tomato plants were transferred to growth cabinets where they were maintained in normal air (0.03% CO2) or in air enriched to 0.1 or 0.5% CO2. CO2enrichment increased net assimilation rate but decreased leaf area ratio. As a result, relative growth rate was greatest at 0.1% CO2and was less in 0.5% CO2than in 0.03% CO2. Gas exchange measurements were made on the third true leaf of plants from different CO2regimes. They indicated that growth under conditions of CO2enrichment affected photosynthesis at an early stage of leaf development (leaf plastochron index (PI) = 5) but not at a later stage (PI = 10.5). The effects were linked to changes in mesophyll resistance, not stomatal resistance. At PI = 5 and under equivalent test conditions of irradiance and CO2concentration, net photosynthesis tended to be increased following growth in 0.1% CO2but was decreased or unchanged by 0.5% CO2. Young leaves developed in 0.1% CO2were less subject to photosynthetic inhibition by atmospheric oxygen and had low CO2compensation points. CO2enrichment also affected the activities of the enzymes ribulose-1,5-bisphosphate carboxylase and glycolic acid oxidase and the enzyme responses corresponded well with the gas exchange responses. The results indicate that photosynthetic adaptations may occur in response to the concentration of CO2present during growth, and that enrichment to concentrations much above 0.1% CO2may be detrimental to net photosynthesis and growth rate.

ISSN:0008-4026    

DOI:10.1139/b80-250

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A 50-fold increase inFuchsia hybridacv. Swingtime was obtained every 4 weeks on B5 medium with eitherN6-benzylaminopurine (BAP) orN6-(Δ2-isopentenyl)adenine (2iP). The shoot tips were established and grown on B5 agar for 2 weeks and then proliferated for 4 weeks on B5 liquid medium with BAP or 2iP. The dose-response relationship for both compounds was expressed by a quadratic curve and on the average the rate of proliferation was greatest with BAP at a concentration of 3 mg/L(1.3 × 10−5 M). The proliferated shoots elongated when the cytokinin was eliminated and rooted readily on B5 medium solidified with agar.

ISSN:0008-4026    

DOI:10.1139/b80-251

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Two new species,Harposporium angularisandHarposporium cylindrosporum, are described as parasitic on a species of bdelloid rotifer belonging to the genusAdineta. InH. angularisthe conidia are long, slender, bent at right angles and taper to an acutely pointed slightly curved apex. Infection is initiated by conidia lodging and germinating in the gullet of the host between the mouth and the mastax. InH. cylindrosporumthe conidia are also ingested but apparently pass through the mastax to initiate infection in the lower gut.

ISSN:0008-4026    

DOI:10.1139/b80-252

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Growth and yield increases, obtained in nodulated soybeans growing in unamended sterile soil by inoculation with the vesicular–arbuscular (VA) mycorrhizal fungusGlomus mosseae, were accompanied by improved P uptake, lower root to shoot ratios, better nodulation with higher nitrogenase activity, and modifications in the pattern of the latter during plant growth. Stimulation of nitrogenase activity occurred early in plant development and preceded plant growth responses by about 2 weeks. Phosphate fertilization increased yield, percent P but not percent N of both mycorrhizal and nonmycorrhizal soybeans, and also modified the pattern and amount of nitrogenase activity during plant growth. Additions of 0.25 g KH2PO4/kg to the soil eliminated the mycorrhizal effect on plant growth, but nodule formation and nitrogenase activity were still significantly stimulated by the mycorrhizal infection. Mycorrhizal effects on nodulation were eliminated with 0.5 g KH2PO4and on nitrogenase activity with the addition of 1.0 g KH2PO4. These higher levels of phosphate fertilization considerably diminished infection and, in particular, fungal spread within the roots.

ISSN:0008-4026    

DOI:10.1139/b80-253

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The ascocarps ofN. galligenaBres. were induced by exposures to white light with variations in time, rhythm, and intensity. It was shown that perithecia could be photoinduced by a single 12-h photoperiod at 10 μW cm−2or by continuous irradiations at 750 μW cm-2for 30 days. These light requirements varied according to the stage of sexual development: perithecia were initiated by a 12-h exposure to light between the 7th and 8th day, but daily 12-h exposures between the 7th and 22nd days were necessary for the best ascocarp development. Ascospore formation did not require light exposure. Light did not produce its effect on sexual reproduction before the 7th day of mycelial growth; its maximum stimulation occurred between the 7th and 10th day.Some biological photoresponses were very similar to the sexual induction which appears in the dark after the addition of mycosporine (P310) to the growth medium. Thus, mycosporine is suggested to act mainly on ascocarp initiation; complete sexual differentiation being achieved by some other photoinduced mycelial products.

ISSN:0008-4026    

DOI:10.1139/b80-254

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The influence of light quality on the sexual reproduction ofNectria galligenaBres. has been studied in three experimental series with progressive accuracy. The last one, as did the two previous experiments, showed that wavelengths of 320, 370, 420, 450 et 480 nm were the most effective for ascocarp production. The sexual induction stimulated by these five wavelengths has been demonstrated for an irradiation of 12 h, at 40 μW cm−2, applied on the 7th day of growth.The action spectrum of the photoinduced sexual stage and the absorption spectra of myceliain vivoand aqueous acellular fungi extracts presented some similarities. The analysis of these results did not allow characterization of the nature of the photoreceptor molecule, but some hypotheses about mycosporine action are suggested by this work.

ISSN:0008-4026    

DOI:10.1139/b80-255

出版商:NRC Research Press    

年代:1980

数据来源: NRC