摘要:

AbstractGermination ofKalanchoé blossfeldianaseeds is absolutely light‐requiring and needs repeated daily light periods.With increasing length of the photoperiod there was a gradual escape from the far‐red inhibition. This escape depended also upon the duration of the far‐red exposure: 10‐second far‐red caused a strong inhibition after a 10‐ to 30‐minute photoperiod and did not inhibit after a 4‐hour day, although the effect of the latter was completely suppressed by 5 minutes far‐red. The action of a 12‐hour photoperiod was not reversed by 10 minutes far‐red but it was by 12 hours far‐red. Light intensity and temperature during the photoperiod were two other important factors influencing the escape from far‐red inhibition. The common features of this escape displayed in very different photomorphological responses are stressed.In order to explain our results in terms of phytochrome action, we distinguish two effects of white light:1) on the initial photoconversion of the inactive to the active PFRform2) on the much slower transformation of PFRto a reacted form P*FR; the latter reaction can also proceed in darkness, but is enhanced by light and is dependent upon light intensity and temperature; this reacted phytochrome is not reversible by a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03642.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractEnzymes, important to protein synthesis, were investigated in young and old leaves ofUrtica dioica. The plants, divided into two groups, were exposed to either 18‐hour or 12‐hour photo‐periods. One group of plants from each photoperiodic regime was subjected to an irradiance of 28 W × m‐2, and the other group of plants to 42 W × m‐2. The enzymes investigated were glutamate dehydrogenase (GDH), aspartate aminotransferase (glutamate‐oxaloacetate transaminase, GOT), and alanine aminotransferase (glutamate‐pyruvate transaminase, GPT), GDH and GOT were determined by means of electrophoretic separation on polyacrylamide and spectrophotometric measurements. GPT was determined only by the latter method.Plants exposed to 18‐hour photoperiods showed much higher GDH activity than did those exposed to 12‐hour photoperiods. The activity of GDH also increased with leaf age. Besides one uniform NAD+‐dependent GDH, two other NAD+‐independent enzymes, showing GDH activity, were identified on polyacryl‐amide gel electrophoresis. The distribution of NADH and NAD+‐dependent GDH activity between young and old leaves was similar under different growth conditions.The activity of GOT was insensitive to environmental changes. The results regarding GPT indicate that this enzyme responded to different photoperiods in the same way as GDH. A correlation coefficient of 0.928 was obtained for the relationship b

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03643.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe ripe seeds ofEranthis hiemalis(L.) Salisb., the winter aconite, contain undeveloped embryos. At 20–25°C the embryos grow only little, and the seeds do not germinate. Rapid embryo development starts if the seeds, after 3 weeks of “after‐ripening” at 20–25°C, are placed at low temperature, 3–4°C; germination then takes place after 2–3 months, Embryo development without germination occurs when the seeds are placed in gibberellic acid solutions at 20–25°C. Embryo development is inhibited at low temperature by the specific inhibitor of gibberellin biosynthesis, 2‐chlorethyl cholin chloride, but is restored by the simultaneous addition of gibberellic acid. It is suggested that one early effect of the cold is to bring about a syn

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03644.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe growth of rice seedlings (Oryza satiraL.) in the presence of ethylene caused a change in the response to light of coleoptile elongation. In plants grown in air without added ethylene coleoptile elongation was promoted by red, far‐red and yellow‐green light only in very young seedlings; in older plants irradiation inhibited the growth of the coleoptile. The effect of growing plants in the presence of ethylene was to prolong the period during which light promoted coleoptile growth. Elongation of the first internode was inhibited by light whether or not the seedlings were grown in the presence of ethylene. A correlation existed between the growth effect of an irradiation and the initial decay rate of phytochrome which was established by the treatment. Regardless of wave length, light sources whose intensities were adjusted to produce a decay rate of about 10% per hour or less induced a moderate rate of coleoptile elongation which persisted for a relatively long period. Irradiation with red or yellow‐green light of higher intensity which produced a higher rate of phytochrome decay induced a higher rate of coleoptile elongation, but growth stopped after several hours. Other observations, however, showed that one cannot establish a general simple correlation between the rate of elongation of rice coleoptiles under light and the status of measurable phytochrome in the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03645.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractNitrate reductase activity was inhibited as a result of reduced soil moisture potentials or application of NaCI to nutrient solutions. The decrease in enzyme activity of wheat seedlings exposed to salinity, was found 24 hours after exposure to stress. The effect of stress on nitrate reductase was found in cell‐free extracts as well as in riro in assays of intact leaf sections.A recovery in enzyme activity was found after irrigation or after removal of seedlings from salinity. While relative water content of the leaves was restored within 3 hours after removal of stress, full recovery of enzyme activity occurred only after 24 hours.Cycloheximide and chloramphenicol suppressed the activity of nitrate reductase in non‐stressed seedlings, but had no effect on the activity of plants exposed to salinity. However, during removal of stress, cycloheximide prevented completely the recovery of nitrate reductase, while chloramphenicol did not interfere with the recovery of the inhibited enzyme activity. It is concluded that a fraction of nitrate reductase may be located in the cytoplasm and lost activity during stress, probably due to inhibited protein synthesis. Another fraction which may be associated with chloroplasts, was inhibited by stress due to conformational changes or partial denaturat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03646.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractChemical and physiological changes occurring in root sapwood of Norway spruce(Picea abies[L.] Karst.), when attacked byFomes annosus(Fr.) Cke, were studied. The transformation of sapwood to reaction zone, induced by the fungal attack, implies a very sharp increase of carbonate content, correlated with higher amounts of potassium, calcium and magnesium. The buffer capacity of the reaction zone is strong, especially in the pH range 6–9. The high peroxidase activity in the rays of the sapwood is almost totally absent in the reaction zone, probably due to inactivating phenolic compounds.o‐Diphenol oxidase was detectable only in the presence of microorganisms.p‐Diphenol oxidase was active in connection with decaying wood but not in the reaction

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03647.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe passive sorption of Pb+2, Cd+2, Zn+2, Co+2, Ni+2, and Mn+2by isolated corn mitochondria was determined, and, except for Pb+2, the maximum sorption for each cation was about 58 nmol per milligram of protein. Sorption of Pb+2was apparently ten times greater, but precipitation may have been the cause of this larger value. The effects of Pb+2, Cd+2, Zn+2, Co+2, and Ni+2on acceptorless rates of electron transport for three substrates were determined. Greater than 50% inhibitions of oxidation were observed for succinate after additions of>0.1 mMCd+2, Zn+2, or Pb+2: for NADH after additions of>0.5 mMCd+2or Zn+2; and for malate + pyruvate after additions of>0.1 mMCd+2. Some inhibition of the rate of substrate oxidation was observed for most cations at higher concentrations. Coupling, as measured by ADP/O ratios, was inhibited at lowest concentrations by Cd+2or Zn+2and at higher concentrations by Co+2or Ni+2. Substantial swelling of mitochondria oxidizing succinate was observed following additions of O.1 mMCd+2or Pb+2, Correlations are drawn between the effects of Pb+2, Cd+2, Zn+2, Co+2, and Ni+2and their sorption to mitochondrial membranes.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03648.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe postulate that single roots ofZea maystransport their absorbed phosphorus nonuniformly to the leaves was tested. Plants were grown under growth chamber conditions for three to four weeks in nutrient solution. At this stage of growth a series of plants was placed into a system in which two roots on each plant were allowed to absorb either33P or32P from uptake solutions for time intervals of up to 24 hours. Plants subsequently were harvested such that each leaf was partitioned into samples containing tissue from one side or the other of the midrib. All samples were assayed for33P and32P and the results were expressed as the amount of total P transported into different plant parts from a single root.Nonuniform P accumulation in the leaves occurred and different patterns of accumulation, dependent on the type of root chosen for uptake were observed. Nearly uniform P accumulation occurred between one side and the other of a given leaf when transport was from radicle roots. In marked contrast, transport from adventitious roots resulted in an alternating pattern of accumulation between one side and the other of each successive leaf up the stem. The seminal root system supplied more P to the older leaves than did the adventitious root system. The nature of these nonuniform P transport patterns is attributed to the vascular organization between roots and leaves.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03649.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAnin vitrobud culture method was devised in order to better understand the control mechanism ofCitrusbud development. This technique offers a new approach to the study of hormonal control of growth, dormancy and flowering cycles in perennial plants.Buds were excised from orchard trees throughout the year, cultured on defined media for prolonged periods, and their vegetative growth responses to various growth hormones were determined. The buds proceeded with their vegetative developmentin vitroand achieved sprouting on a basal medium. The various growth regulators affected both the time required for sprouting (TRS) and the type of growth. In summer buds, IAA delayed sprouting, while GA enhanced it and caused shoot elongation. Cytokinins specifically induced the formation of numerous adventitious buds, whereas ABA completely inhibited sprouting; this inhibition, however, was reversible. A marked decrease in total protein and in the rate of its synthesis was evident during the first 20 days of sprouting induction and early bud growth.The annual growth rhythm was determined in spring buds sampled and cultured throughout the year, and an innate dormancy of citrus buds was revealed. Both the dormancy and the sprouting periods of budsin vitrocorresponded to the natural periods occurring under field conditions. The effect of exogenous IAA, GA and cytokinins on the TRS varied at different periods along the season, suggesting the concept of “critical levels” in the endogenous balance of hormo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03650.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe composition and amount of carotenoid pigments were determined in etiolated seedling leaves of 6 barley (Hordeum vulgareL.) mutants, comprising 1xanthaand 5tigrinamutants. All mutants had on a mole basis approximately the same content of carotenoids as the wild type.The mutantsxan‐u21,tig‐n32, andtig‐33contained significantly higher amounts of carotenes than the wild type, ranging from 32 to 68% of the total carotenoid content as compared to the 4–8% found in the wild type. In the mutantstig‐b23andtig‐o34, only a slight increase in the amount of carotenes was notable. The carotene content and composition intig‐d12was indistinguishable from that of the wild type.The carotenes extracted fromxan‐u21,tig‐b23,tig‐n32,tig‐33, andtig‐o34were characterized by adsorption chromatography and spectrophotometry. Mutantxan‐u21is in the dark blocked in β‐carotene synthesis, and accumulates the aliphatic polyenes: phytofluene, proneurosporene, poly‐cis‐lycopenes, neo‐lycopene and lycopene. The other four mutants synthesize β‐carotene, but accumulate in addition various higher saturated carotenes, the main components being ζ‐carotene intig‐b23, a lycopenic pigment intig‐n32andtig‐33, and lycopene intig‐o34.Accumulation of higher saturated carotenes appears correlated with specific aberrations of the membrane structure in plastids. The regulation of carotene and protochlorophyllide syntheses in etioplasts are closely linked as shown by the single gene mutants which affect both pathways. However, several mutants have been identified which cau

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03651.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY