摘要:

The occurrence of growth regulators and nucleic acids in buds of red pine trees has been investigated in relation to seasonal change, position of the bud in the crown, and age of the tree. The regulators were extracted, separated by chromatography, and assayed by anAvenastraight-growth test. Three growth promoters and an inhibitor were found in the buds on all occasions. All of them affected the growth of hypocotyls of red pine seedlings as well asAvenainter-nodes, and none gave an indole reaction. The regulators varied in concentration in relation to season, age, and bud position. The individual growth promoters varied independently, one of them, designated as P1, being more variable than the others. Changes in the inhibitor were frequently, but not invariably, reciprocal to those of P1. There is evidence that individual growth promoters may be concerned with separate aspects of growth. The balance between P1 and the inhibitor was related to extension growth, with the notable exception that a balance favorable to growth reappeared in September, when no growth occurs. RNA concentration declines during the summer and a deficiency of this nucleic acid could be implicated in the cessation of growth.Treatment with ammonium nitrate fertilizer caused a shift from male to female cone production and a localized increase in the number of shoots that developed in the following year. These effects were accompanied by changes in concentration of growth promoters in the buds.

ISSN:0008-4026    

DOI:10.1139/b66-087

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The addition of gibberellin A3(GA) to leaf discs ofTaraxacum officinaleWeber retards their senescence and delays the decline in the levels of chlorophyll, protein, and RNA. Incorporation of14C leucine and14C adenine into protein and RNA respectively was increased by GA. This enhancement of protein and RNA synthesis did not occur if the discs were supplied with actinomycin D before treatment with gibberellin. If, however, actinomycin D was added after the gibberellin treatment then the stimulatory effect of the hormone was maintained. These results suggest that the retarding action of gibberellins on leaf senescence could be mediated through a regulation of RNA synthesis that is DNA dependent.

ISSN:0008-4026    

DOI:10.1139/b66-088

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Fifty-four sites were selected in a number of mires in Ontario, and rates of water movement were measured on a number of occasions. The rates of water movement ranged from less than 0.1 cm sec−1to over 8 cm sec−1. The oxygen concentration of the mire waters increased with increasing flow rate, approaching saturation at rates over 1 cm sec−1. From a model it was shown that at a flow rate of less than 0.3–0.4 cm sec−1the diffusion of oxygen into the water would be similar to simple diffusion into a stationary water surface, and because of the respiration of roots and microorganisms in the peat, the oxygen would tend to be depleted. Above flow rates of 0.4 cm sec−1the water is agitated, and is continually replenished with oxygen from the atmosphere. Reduced states of iron and manganese were shown to be in solution at concentrations greater than 0.1 mg/1 only at low rates of water flow. The pH was also shown to increase with faster rates of water movement, the increase depending on the base status of the mire. Aluminium is in solution only in situations of low water movement where more acidic conditions are prevalent.

ISSN:0008-4026    

DOI:10.1139/b66-089

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The effects of sodium or potassium sulfate on RNA metabolism in soybean roots were examined. Two soybean varieties differing in salt tolerance were used.Growth for 6 days in 50 mMsulfate salts inhibited dry weight production and DNA synthesis in both varieties, the sodium salt being more inhibitory than potassium. Salinity, whether sodium or potassium, nearly stopped protein synthesis and retarded RNA synthesis.Both salts accelerated the endogenous degradation of RNA in root homogenates, sodium being more effective than potassium. Ribosomal RNA was degraded primarily. In the salt-tolerant soybean, total RNA of root tips did not decrease on a DNA basis; only a small decrease occurred in the salt-sensitive variety.Nucleic acids from roots were resolved on methylated albumin columns. Oligonucleotides increased with salinity in both varieties. Sodium sulfate drastically reduced32P incorporation into nucleic acids in the salt-sensitive soybean, but less in the tolerant variety. Potassium salinity had little effect on radioactivity incorporation. Incorporation of32P into the DNA fraction was reduced more in sodium than in potassium salinity, with the salt-sensitive soybean being affected most.Aberrations in RNA metabolism are discussed in relation to reduced growth in saline media.

ISSN:0008-4026    

DOI:10.1139/b66-090

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Acid-soluble nucleotides in senescing wheat leaves tended to decrease with time in a manner similar to the decline in RNA.2Little change was apparent in the free nucleotide: RNA nucleotide ratio. Treatment with kinetin reduced, but did not prevent the loss of soluble nucleotides. The greatest losses occurred in the nucleoside diphosphates. Rust infection increased each of the soluble nucleotides even more rapidly than it increased RNA content. Rust uredospores, themselves, appeared to possess a large soluble nucleotide pool. Uridine and adenosine derivatives were the only nucleotides consistently found. Uredospores and rust-infected leaves differed from uninfected leaves in possessing a large amount of a UDP-N-acetylglucosamine complex. The results are discussed in relation to previous measurements of RNA in senescing and rust-infected leaves.

ISSN:0008-4026    

DOI:10.1139/b66-091

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The percentage number of cells in S (cells which are undergoing DNA synthesis at time of treatment) in 4-mm root tips during early stages of germination was determined by tritiated thymidine and liquid emulsion autoradiography. Labeled nuclei were observed within all anatomical regions of the primary root 24 hours after seeds were sown and the observed labeling did not follow the known pattern of mitotic reactivation. This would indicate that DNA synthesis was not closely-related to the onset of mitosis during germination. The percentage of cells labeled was 10% at 24 hours, approximately 3% at 32 through 48 hours, and 10% at 60 through 96 hours after seeds were sown. The 3% labeled cells at 32–48 hours after planting may indicate a large population of G2cells but this was not in accordance with a previous study onGlycine max, in which DNA per cell was determined. A greatly reduced labeling over the stelar and common initial regions indicates the existence of a quiescent zone in the embryonic root.

ISSN:0008-4026    

DOI:10.1139/b66-092

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Myzus persicae(Sulz.) transmitted a second component virus from a turnip latent virus complex to healthyPhysalis floridanaRydb. seedlings after passage of the complex through turnip (Brassica rapaL.). The symptoms were small yellow specks on the leaves which became more pronounced on new growth when infected plants were cut back. Combined transmissions with the first component, mild chlorosis virus, produced yellow-net symptoms characteristic of the complex.The second component was transmitted fromP. floridanatoP. floridanaby graft and of six aphid species tested, onlyM. persicaetransmitted it. The first component alone was transmitted from the complex byM. circumflexus(Buckton). Only a few plants developed symptoms of the second component after inoculation by aphids, and data from some tests indicated that infectedP. floridanamay sometimes be symptomless. Both components were transmitted in the persistent or circulative manner and were not sap-transmissible.

ISSN:0008-4026    

DOI:10.1139/b66-093

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Twenty-three cultures ofVerticilliumwere isolated from 10 species of horticultural plants in Quebec. On the basis of morphological and physiological characters in culture the isolates were grouped into three species:V. albo-atrumR. and B.,V. dahliaeKleb., andV. nigrescensPethybr. These species must be distinguished to eliminate the current confusion on host specialization inVerticilliumand the influence of environment onVerticilliumwilt.

ISSN:0008-4026    

DOI:10.1139/b66-094

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Plants ofPhaseolus vulgariswere grown under controlled conditions at day/night temperatures of 24.0/15.5, 29.5/21.0, and 35.0/26.5 °C for measurement of blossoming and fruit set patterns over a 60-day period of blossoming. Fruit removal at a large green stage was compared with fruit removal at dry maturity and with removal of all blossoms. Removal of fruit at a large green stage resulted in cyclic patterns of blossoming at the two lower temperatures with a greater proportion of blossoms setting fruit in later cycles. When all blossoms were removed, the cyclic pattern was not as pronounced. When fruit were removed at dry maturity only one blossoming cycle occurred and the plants senesced. The numbers of blossoms and fruit were greatest at 29.5/21.0 °C.

ISSN:0008-4026    

DOI:10.1139/b66-095

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Particles within lesions of leaf tissue infected with either tobacco necrosis virus (TNV) or southern bean mosaic virus (SBMV) were compared with particles in embedded pellets of purified preparations of these viruses by an examination of thin sections. The mode of the diameters of particles in tissues and pellets was 20.5 mµ.It is assumed that the particles in infected tissues are virus particles on the basis of their similarities in size, shape, and arrangement with the particles in purified preparations.

ISSN:0008-4026    

DOI:10.1139/b66-096

出版商:NRC Research Press    

年代:1966

数据来源: NRC