摘要:

AbstractRed light with a wavelength of 660 nm promotes germination of longleaf pine (Pinus palustrisMill.) seeds, and far‐red light (730 nm) inhibits germination. The promotion‐inhibition process is repeatedly reversible, indicating that germination is controlled by the photoreversible reaction of phytochrome. Response varied greatly between single‐tree lots and was dependent on the length of time seeds were imbibed at 5°C. Dry seeds did not respond to light treatments when they were subsequently imbibed and tested in darkness. Stratification for 28 days essentially removed the light requirements for germi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06385.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe variation in Skeletonema cells grown at 3 klux continuous illumination and 20°C is reported. Four different types of lamps gave no difference in the photosynthetic characteristics. The average diameter of the cells decreased from 8–3.5 μ during their six months vegetative period. The ratio between the pigment content in the largest and the smallest cells was about 2:1. A good correlation between cell volume and chlorophyllacontent was found for this species. The content of chlorophyllcgenerally varied between 4 and 17 per cent of the chlorophyllacontent. — A distinct correlation between the chlorophyllacontent and the rate of photosynthesis per unit of cells at low light intensity was found. The rate of photosynthesis, in mg C per mg chlorophyllaand hour at 1 klux, varied between 0.40 and 0.70 for all 60 experiments with an average value of 0.56. The corresponding value for cells deficient in phosophorus was 0.19 and for cells deficient in nitrogen 0.09. — The material also showed a good correlation between the rate of photosynthesis per cell at 1 klux and the light‐saturated rate of photosynthesis. Ikvaried between 7 an

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06386.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe induction of seedlings with multiple shoots by thein vivotreatment of embryos of wheat by herbicides such as 2,4‐D, 2,4,5‐T, MCPA and TBA as well as mixtures of these substances was studied. Treatment during the first week of embryo development was necessary for the production of additional shoots in the seedling; later treatment gave rise to callused seedlings. Other seedlings such as oats, barley and rye, and other species of wheat were treated, but seedlings with extra shoots were not produced, though callused seedlings were recove

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06387.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of red and far‐red treatment on chlorophyll synthesis in dark‐grown bean leaves was studied at various ages. Although the effect was pronounced in the old leaves, no effect was observed in the young ones (4 days old). In the 5‐day old leaves a measurable effect of red light pretreatment can be observed, whereas the far‐red reversal effect was not observed. — The length of the dark period between the red pretreatment and the continuous illumination is also age dependent. Leaves older than 6 days show a maximum at about six hours, while in the young leaves the red light effect increases with the time of dark incubation up to the 24 hours tested. — The reversal effect of far‐red light on protochlorophyllide regeneration was also examined. The far‐red light has no reversal effect on leaves younger than 6 days old, while on the old leaves it has

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06388.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe kinetics of induction of heat stability of cytoplasmic proteins and lipoproteins by auxin (2,4,‐D) were determined for basal sections of soybean hypocotyl. Maximum heat stabilization occurred after 4 h of tissue incubation with 10‐5M2,4‐D. The effect was less pronounced or absent with longer incubations. Membrane fractions sedimenting between 10,000 and 100,000gand proteins of the 100,000gsupernatant were most affected. The auxin‐induced protein aggregation response varied among experiments. With many tissue lots, the response was small or absent even though the tissue responded to the auxin uniformly by increased growth. The magnitude of response was proportional to the logarithm of auxin concentration but with low 2,4‐D the portion of the homogenate protein coagulated by heat was increased and with supraoptimal concentrations it was decreased relative to the control. The smallest auxin‐induced change in heat coagulability was observed at the auxin concentration nearest the optimum for growth. No direct correlation was found between the auxin‐induced protein and lipo‐protein aggregation phenomenon and total protein, chloroform‐extractable lipid, residual lipid, growth or tissue deformability. Total sulfhydryl equivalent of the homogenates, however, did correlate with auxin effects on aggregation. This result, plus experiments where homogenates were exposed to oxidizing or reducing conditions, suggests that heat stabilization and associated protein aggregation phenomena are related to conversion of protein sulfhydryl to intramolecular disulfide bonds. No significance is attached to heat stabilization of cytoplasmic proteins as a requisite of aux

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06389.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractA method for growingFusarium oxysporum, a mycelial fungus, and a technique for its use in mineral uptake studies have been described. Some general characteristics of the uptake process were determined. The fungus, grown for 54 hours, was found to take up as much K as 15 to 20 meq/100 g dry weight in 2 to 4 hours from a solution of 5 meq/l KCl. Approximately 3 to 5 meq of this uptake was readily removed by a CaCl2rinse. The uptake was only slightly sensitive to pH over the range of 4 to 9. Below pH 4 uptake dropped rapidly. The age of the culture appeared to be the dominant factor in determining the rate of uptake. In contrast to other fungi, the presence of glucose during uptake was detrimental to K uptake. Conditions unfavorable for metabolic activity as low temperature, anaerobiosis, or the presence of DNP markedly reduced the uptake rate. Although the fungus took up Na from single salt solutions nearly as well as K, the latter ion was much preferred in mixtures of the two ions. The organism showed no significant metabolic uptake of Ca or Cl. During uptake from KCl solutions, the organic acid content increased. The increase, chiefly in succinic acid and to a lesser extent in acetic and citric acids, amounted to about half the K uptake. The remainder of the K taken up was correlated with a roughly equivalent efflux of cellular Mg.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06390.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIsolated mitochondria of wheat shoots oxidize α‐ ketoglutarate, DL‐malate succinate and NADH with good relative respiration control and ADP: O ratio. They have high affinity for α‐ketoglutarate and NADH as substrates and utilize malate and succinate with a respiration ratio of about one‐half of α‐ketoglutarate. The average ADP : O ratios approach the expected theoretical values,i.e., 3.6 ± 0.2 for α‐ketoglutarate, 1.8 ± 0.2 for succinate, and 2.8 ± 0.2 for malate. The ADP: O ratio with NADH is 1.8 ± 0.2. The maximum coupling of oxidation and phosphorylation is obtained at concentrations of 10 mM, 2 mM, 10 mMand 8 mMfor α‐ketoglutarate, NADH, malate and succinate, respectively. — Wheat mitochondria have little or no dependence on added cofactors. Mitochondria prepared by our procedure apparently retain sufficient amounts of endogenous cofactors required for NAD‐linked systems. FAD+is found to improve succinate oxidation. Cytochromecdoes not have any significant effect on respiratory parameters of wheat mitochondria. — Wheat mitochondria are some ‐what resistant to DNP at 1.7 × 10‐5M. Malonate seems to improve coupling of α‐ketoglutarate oxidation. Other Krebs cycle intermediates have been tested on three major substrates of TCA cycle,i.e.,

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06391.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe distribution of aluminium, nitrogen, calcium and phosphorus in the cortex cells of bean and barley roots was investigated by means of X‐ray microanalysis. Aluminium was apparently localized inside the cell‐lumens and its distribution over ‐lapped that of nitrogen. More calcium was observed in the cell walls. No correlation between the distribution of aluminium and phosphorus was

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06392.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractDuring investigations of their metabolism fragments of plant tissue are most commonly incubated in watery solutions in order to replace the conditions within the intact organ approximately. — This paper reports experiments performed to investigate the influence of a hypotonic medium on several parameters of importance in cell metabolism (protein synthesis, enzymatic activity, concentrations of metabolic intermediates, respiration and cell division). — It could be shown that protein synthesis is severely inhibited in hypotonically exposed potato tuber discs. As a consequence the activities of two dehydrogenases of the pentose phosphate shunt (glucose‐6‐phosphate‐ and 6‐phosphogluconate‐dehydrogenase) are very low as compared with tissue in air. Since the activated pentose shunt evidently contributes to the respiratory reaction after derepression of the tissue, lowered activities of these dehydrogenases must consequently result in lower respiratory activity. This is actually realized in washed tissue. Likewise the mitotic activity is inhibited to a considerable extent. — The destruction of permeability barriers within the cell as a consequence of slicing causes leakage of a variety of metabolites such as glucose, glucose‐6‐phosphate, fructose‐6‐phosphate and pyruvate. Thus leaching of metabolic active substances is certainly one of the causal factors in the complex reaction of tissue slices exposed to a hypotonic medium, although such important parameters as changed gas conditions and the various effects of altered hydration of cell cytop

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06393.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractCarotenoid synthesis in the fruit of tomato mutants is under gene control. Since undifferentiated plant cells are presumably totipoltent, the callus tissue should be able to produce the carotenoids typical of the genotype. The carotenoids of masses of callus derived from hypocotyls of thered ghostandtangerinetomatoes were extracted and characterized by means of column and thin layer chromatography, chemical and spectral properties. Thered ghostcallus contained predominantly phytoene and phytofluene; thetangerinecallus had primarily ζ‐carotene and prolycopene. Thus under our cultural conditions, carotenoids typical of the fruit rather than the leaf were produced, albeit in much reduced quantiti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06394.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY