摘要:

The anatomy of root initiation ofHydrangea macrophyllaand associated changes in protein and DNA synthesis during adventitious root formation are described. Observations showed that adventitious roots originated from preformed root initials in the phloem ray parenchyma cells. The roots appeared 10 to 12 days after the cuttings were made.The total protein content of the root initials increased over 100% in the first 4 days, while there was no rapid increase in DNA content of the cells until the sixth day. The estimated mean content of total protein per cell stabilized on or before the sixth day from the time the cuttings were made, and thenceforth appeared to come into equilibrium with the rate of cell division.

ISSN:0008-4026    

DOI:10.1139/b72-056

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Bud growth on isolated rhizomes ofAgropyron repensshowed a basipetal gradient of decreasing activity and was strongly inhibited at the basal nodes. This evident polarity was correlated with a gradient of decreasing nitrogen content at successively older nodes and with an apparent translocation of nitrogen from the basal to the apical nodes. Isolating the buds from one another reduced growth of the apical buds and prolonged the growth of buds at the basal nodes so that the polarity of bud growth, although still apparent, was much reduced.Supplying nitrogen as NH4NO3through the cut end of rhizomes still attached to the parent plant caused apical buds to develop as shoots instead of rhizomes. Increasing the nitrogen supply to the rooting medium extended this response to buds at older nodes, restricting rhizome production to basal buds whose growth was inhibited in low nitrogen rhizomes.Buds developing as shoots had a considerably higher total nitrogen and moisture content and a lower dry weight than buds developing as rhizomes.The results emphasized the importance of the nitrogen supply not only in determining the polarity of bud growth and the degree of correlative inhibition, but also as a morphogenetic factor controlling bud development.

ISSN:0008-4026    

DOI:10.1139/b72-057

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The growth of Marquillo × Kenya Farmer 1 heat plants has been shown to be irreversibly terminated if they are exposed to a 16° temperature when 10 days old and it has been proposed that this low temperature sensitivity proceeds through a rapid inactivation of the shoot apical meristem. Histological and microautoradiographic techniques were used to study the effects of 16° treatment on the morphology and meristematic activity of the young shoots of both Marquillo × Kenya Farmer 1 and normal Marquillo plants.Within 12 h of the beginning of 16° treatment, damaged cells were visible in the young developing leaf and stem tissues and such cells became numerous after longer periods at 16°. The cells most rapidly destroyed were those surrounding the vascular bundles in both leaf primordia and stem tissues and the extent of damage in a tissue was closely related to the stage of vascular differentiation in the adjacent bundles.Cell division in the apical meristem of the main shoot was inhibited even more rapidly. The proportion of cells dividing and the incorporation of3H-thymidine into the nuclei of meristem cells decreased rapidly at 16° and the reversibility of these effects was similar to that of the whole plant effects.It is suggested that the cessation of growth in Mql × KF 1 exposed to 16° is due to the lack of cell division and that the permanence of this effect is due to the extensive cell destruction that occurs in the meristematic regions.

ISSN:0008-4026    

DOI:10.1139/b72-058

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The genusAsterobolusis proposed for an undescribed hyphomycete characterized by multicelled, star-shaped conidia forcibly discharged by a downfolding of the radiating appendages and rupture of the sporogenous cell.Asterobolus gaultheriaesp. nov. is the causal agent of a leaf spot ofGaultheria shallonPursh. The fungus also infects species ofVaccinium, Pteridium, Malus, andMenziesia. Sclerotia were observed only onGaultheriaand infections of other hosts were found only near infectedGaultheria. In addition to the star-shaped conidia, aGliocladium-like conidial stage was also observed in cultures of the fungus.

ISSN:0008-4026    

DOI:10.1139/b72-059

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The development of the basidiocarp ofCalocera corneain the natural and cultural environments is described. The structural unit is a narrow, unmodified hypha with the capacity for pigment and gel formation. In the basidiocarp the hyphae become organized into a central zone of compact, parallel hyphae, a median zone of interwoven hyphae with numerous spaces containing gelatinous material, and an outer zone composed of bifurcate basidia each bearing two basidiospores.Primordia and basidiocarps show rapid growth with marked sensitivity to relative humidity and sporulation frequently takes place before basidiocarp development is complete. Short periods of rapid growth alternate with long periods of inactivity during which the formation of fungal gel and carotenoid pigments probably aids in survival.

ISSN:0008-4026    

DOI:10.1139/b72-060

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The genusSporormiais restricted to the type speciesS. fimetariaDeNot.,S. fimicolaAhmed & Asah andS. mirabilisBret. & Faur., in which the ascospores are arranged in a truncate bundle, parallel to the ascus and surrounded by a common gelatinous sheath. The cells of the ascospores are without germ slits.InSporormiella, which is regarded as a distinct genus, the ascospores are not arranged in a truncate bundle. Each spore has a distinct and separate gelatinous sheath and each cell of the ascospore has an elongated germ slit. The type species isS. nigropurpureaEll. & Ev.The following 35 species ofSporormiaare transferred toSporormiella:S. affinisSacc.,S. americanaGriff.,S. antarcticaSpeg.,S. australisSpeg.,S. bipartisCain,S. capybaraeSpeg.,S. chaetomioidesGriff.,S. commutataNiessl,S. corynesporaNiessl,S. dakotensisGriff.,S. heptameraAuersw.,S. herculeaEll. & Ev.,S. insignisNiessl,S. irregularisI. Egel.,S. kansensisGriff.,S. lageniformisFuckel,S. lataGriff.,S. leporinaNiessl,S. longisporaCain,S. megalosporaAuersw.,S. minimaAuersw.,S. muskokensisCain,S. ontariensisCain,S. ovina(Desm.) Sacc.,S pascuaNiessl,S. pentameraOud.,S. pilosaCain,S. pilosellaCain,S. polymeraCain,S. pulchellaHansen,S. pyriformisSpeg.,S. scandinavicaI. Egel.,S. schoterrianaBret. & Faur.,S. splendensCain,S. vexansAuersw.There are 22 new species described in the genusSporormiella, as follows:S. alloimera, S. anisomera, S. calomera, S. cylindrospora, S. cymatomera, S. decamera, S. dodecamera, S. dubia, S. euryspora, S. isomera, S. longisporopsis, S. minimoides, S. minipascua, S. octonalis, S. platymera, S. schadospora, S, septenaria, S. systenospora, S. subtilis, S. teretispora, S. tetramera, S. trogospora.These coprophilous species are from Argentina, Canada, Mexico, and the United States.A total of 66 species are described, 61 of which are illustrated. Keys to the species ofSporormiaandSporormiellaare included.

ISSN:0008-4026    

DOI:10.1139/b72-061

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Recent findings based on light microscopy, electron microscopy, electrical gradients, microinjection, and tracer feeding, all on isolated but living phloem strands ofHeracleumare here summarized and collated. A new theory of translocation is presented in which sucrose transport occurs in two chief modes. The first is based on microperistaltic movement of contractile lipoprotein which is thought to extend axially through the sieve tube. The second is a mass flow of solution around the contractile microfibrillar material, but chiefly activated by it. The microfibrillar material transports sucrose in pulses at about 400 cm h−1and this mode of translocation is stopped by cold blocks and desiccation, but not by callose. The mass flow mode is slower and is stopped by callose formation and also by the cessation of activity of the microfibrillar or pulsing mode. A third small surface-layer component of translocation is also indicated, operating at speeds above 1000 cm h−1.

ISSN:0008-4026    

DOI:10.1139/b72-062

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A chytrid tentatively identified as aPhlyctochytriumsp. (isolate 71-1-E) was isolated fromBryopsis plumosacollected in the York River estuary, Virginia (salinity 18–22‰). The morphology of isolate 71-1-E is highly variable and is thought to depend, at least in part, on the substrate. The nature of the rhizoidal system, sporangial size, number and position of the discharge papillae, and the relation of the thallus to substrate were found to vary. Perfusion chamber studies indicate that the germ tube enlarges and is incorporated into the developing sporangium. During discharge pore formation, a rather electrontransparent substance was deposited at the pore site. This was followed by the accumulation of electronopaque substances, rupturing and breaking down of the sporangial wall, and finally the deliquescence of the discharge plug, leading to the formation of the discharge pore.

ISSN:0008-4026    

DOI:10.1139/b72-063

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A review is presented of the taxonomy of four arctic and (or) alpine species ofSenecio, S. conterminusGreenman,S. hyperborealisGreenman,S. resedifoliusLess., andS. cymbalarioidesBuek. Of these, the first three have been recently claimed by one authority or another to have disjunct distributions between the Alaska–Yukon area and the Rocky Mountains. Investigations based on morphology (including that of the pollen) and cytology confirm the recognition of the four species and have furnished clear evidence for the recognition of a new species,S. ogotorukensisPacker, a description of which is provided. It is concluded from the author's understanding of the taxonomy of these species that none has a disjunct distribution between the Alaska–Yukon area and the Rocky Mountains.

ISSN:0008-4026    

DOI:10.1139/b72-064

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Indices of atmospheric purity (IAP) of 31 sites, selected in the SO2-polluted as well as in the non-polluted areas around Sudbury were determined on the basis of number, frequency-coverage, and resistance factor of the epiphytes ofPopulus balsamifera. Based on these indices, arranged into convenient ranges, the investigated area was delimited into five different IAP zones. These zones were then compared with SO2pollution zones based on the ground-level average concentration of the gas prevailing in the area. From this comparison it is clear that the biological method provides a valid, quick, and economical way for assessing and mapping the long-range effect of pollution of a given area.

ISSN:0008-4026    

DOI:10.1139/b72-065

出版商:NRC Research Press    

年代:1972

数据来源: NRC