摘要:

AbstractRNAs extracted from crown‐gall tumors, induced byAgrobacterium tumefaciens(strain B6) on stems ofDatura stramoniumL., have been isolated by the phenol method and purified through Biogel P 60 columns. These RNAs have been transformed into complexes withl‐amino acids by incubation in a medium containing: Tris HCI buffer, pH 7.6, ATP, MgCl2, a mixture ofl‐amino acids and a polypeptide synthetase purified fromAlcaligenes faecalis. The inoculation of stems of Datura plants with these complexes induces the development of nodular outgrowths, whereas other complexes made from RNAs isolated from healthy Datura plants, fromAgrobacterium tumefaciens, Escherichia coliandAlcaligenes faecalisdo not cause any hyperplasia under our experimental conditions. The analysis of the results obtained, supported by histological studies of the outgrowths, suggests that these neoformations should be of tumoral n

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03905.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractVegetative shoots of coastal Douglas fir [Pseudotsuga menziesii(Mirb.) Franco] seedlings rapidly metabolized 1,2[3H]‐gibberllin A4(GA4) to GA2, GA34and 6 unknown acidie, ethyl acetate‐soluble compounds. The kinetics of formation of each compound depended upon the stage of ontogeny, metabolism being most rapid during bud set and bud break and least rapid during elongation. Translocation of radioactivity was greatest at the bud set stage. By hour 72 large amounts (65%) of neutral, ehter‐soluble compunds were formed at the stage of bud break and lesser, but significant amounts (40%) at bud set. Less than 15% of the radioactivity went into neutral ether during the elongation stage. Douglas fir appears to have an efficient system for con‐version of the relatively non‐polar GA34. This, coupled with the formation of neutral, ether‐soluble and acidie,n‐butanol‐soluble substances, may regulate the effective level of biologically active exogenous and/or endogenous GAs

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03906.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractMeasurements were made of the growthof the sub‐apical region of decapitated, etiolated epicotyls ofPisum sativumL. cv. Alaska after treatments with indoleacetic acid (IAA), gibberellic acid (GA) and triiodobenzoic acid (TIBA). Growth was measured either at the end of a 2‐day period, at short intervals during growth, or was monitored continuously for 2–3 h using a position‐sensing transducer.In experiments measuring growth after 2 days, high levels (0.1–10 μg/plnat) of IAA caused expansion, whereas similar levels of GA caused elongation. When both hormones were applied together, the effects of IAA were dominant and expansion ensued, even when GA was present at 100 times the amount of IAA. Very low amounts of IAA (0.5–5 ng/plant), however, caused elongation. The elongation elicited by high GA or low IAa was inhibited to a similar extent by TIBA and this inhibition of elongation was associated with an increased expansion at the extreme tip. When application of the hormones was delayed, GA‐induced elongation was reduced considerably, IAA‐induced elongation was lessened somewhat and IAA‐induced expansion was partially converted into elongation.In experiments measuring elongation at short intervals, high levels of IAA caused rapid elongation followed after 3 to 6 h by expnasion. Both GA and low levels of IAA extended the duration of elongation with little apparent effect on the rate of growth. In fast‐growth experiments, low, intermediate and high levels of IAA doubled the rate of elongation with a lag period of about 20 min, whereas GA had at most a very slight stimulatory effect on the growth rate.It is concluded that the main role of GA in this system is to maintain physiological levels of IAA in the growing zone and that the level of IAA present determines whether elongation or expan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03907.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe light requirements for induction of flowering by a long dark period were investigated in dark‐grown seedlings ofPharbitis nilChois, cv. Violet. The cotyledons bcame photoperiodically sensitive to a 24 h dark period by two 1 min red irradiations (6.3 μmol m−2S−1) separated by a 24 h dark period. The reversibility of the effect of brief red irradiations, and the effectiveness of low energies of red irradiation suggest the involvement of phytochrome in the induction of photoperiodic sensitivity. Partial de‐etiolation occurred after these brief periods of red irradiation but the seedlings were not capable of net CO2uptakeeven 7 h after the start of the main light period that followed the critical dark period. A changing response to the duration of the priod of darkness given between the two short red irradiations showed the the correct phasing of an endogenous photoperiodic rhythm is needed for the attainment of photoperiodic sn

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03908.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractLosses of one naturally occurring cytokinin (zeatin) and one synthetic cytoknin (kinetin) were determined during purification of turnips (Brassica compestris) infected byPlasmodiophora brassicae(clubroot). A known amount of zeatin and 8‐14C‐kinetin was added after homogenization of plant material in ethanol or water. The commonly used practice to purify the aqueous residues of the homogenate by partitioning with petroleum ether was omitted because of emulsion formation. Losses due to emulsion formation and occlusion of 8‐14C‐kinetin into non‐water soluble plant material could be prevented by extractionof clubroot tissue with water instead of ethanol. To minimize enzyme activity the aqueous homogenate was kept at 100°C for 5 min. High molecular weight compounds were removed by dialysis against water and the diffusible fraction was partitioned withn‐butanol at pH 8.2.It was shown that a rapid evaporation ofn‐butanol under reduced pressure at high temperature caused less breakdown of 8‐14C‐kinetin than prologned treatment at a low temperature.To minimize breakdown to zeatin riboside the butanol fraction was purified further on cation cellulose‐phosphate exchanger instead of on strong acid Dowex H+. 8‐14C‐kinetin was separated from zeatin by column chromatography on Sephadex LH20, and yielded 86% of the amount originally added to a plant homogenate.The zeatin containing fractions were further purified on thin layer chromatography (TLC) silicagel plates and injected into a high pressure liquid chromatograph. A yield of 60% could be estimated from the amount (15 μg) orignally adde

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03909.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe transpiration responses of primaryArenaleaves to red and blue light steps were investigated. The response to a red light step was a so‐called slow response (with a rise time of about 8 min). The response to a blue light step consisted of both a slow, and a rapid response (with a rise time of about 2 min). CO2‐free air outside the leaf eliminated only the slow response,i.e.in CO2‐free ait the plant responded to blue light steps but not to red ones. A short exposure of red light prior to a blue light step enhanced the rapid response. The same enhancement of the rapid response could be achieved by means of a temporary pretreatment with CO2‐free air. The magnitude of the rapid response was dependent on the blue light irradiance and no threshold effects could be detected. — The experimental results are discussed by means of a model, based on stomatal regulation by, ion transport between the subsidiary cells and the guard cells. It is suggested that the slow transpiration response is due to CO2‐regulation of the stomatal aperture and that the rapid response reflect a CO2‐independent blue light sensitive process, which acts directly on the ion transport through the subsidiary and guard c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03910.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn a solution culture experiment with 4‐week‐old barley plants (variety Villa) the influence of NaCl salinization and of KCl additions on the uptake and turnover of labelled N (15NH415NO3) was studied. Labelled N was applied for 24 h at the end of the growth period.Salinization impaired growth and uptake of labelled N. The incorporation of labelled N into the protein fraction, however, was improved by NaCl salinization. Additions of KCl to the nutrient solution diminished the negative effect of NaCl salinization on growth. At both NaCl salinization levels (60 and 120 mM) K additions favoured the uptake of labelled N and particularly its incorporation into the protein fraction.It is suggested that the negative influence of the NaCl stress is not primarily due to an impaired protein synthesis, but is possibly caused by a deterimental effect of Na on other metabolic proces

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03911.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractRoot initiation inCucurbitacotyledons excised at various ages was studied in nutrient solution and water. The time required for root initiation depends on the age of the cotyledon and on the rooting medium. Nutrient solution favoured root formation. Maximum number of roots, maximal total root length, and maximum life‐span were found with cotyledons excised at an age of 14 days. Excision earlier or later resulted in less roots, less total root length, and shorter life‐s

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03912.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractTwo mutants ofChlorella vulgarischaracterized by higher and lower content of sulphur amino acids compared with the wild strain were assayed for the efficiency of the sulphate uptake mechanism. In both mutants uptake exhibited positive cooperation kinetics and was strongly stimulated by sulphate starvation. Stimulation was depressed by cysteine and to a higher extent by methionine. Mutations affected the uptake efficiency concordantly with the level of sulphur amino acids. Addition to the starved strains of sulphate or chromate reduced the induced transport to the lower values of the non‐starved strains. Addition of cycloheximide during the induction period prevented a further enhancement of transport without depressing the attained rate in the low sulphur mutant; it was followed by a rapid fall to the non‐induced rate in the high sulphur mut

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03913.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractLow‐energy blue light (450, 475 nm) has been found to induced unfolding of etiolated barley leaves (Hordeum rulgarecv. Ingrid). This induction can be reversed by far‐red light. Barley leaf unfolding is normally stimulated by red light, reversed by far‐red light, and can be considered to be a typical phytochrome controlled response. It is possible to explain the effects by red and blue light as mediated by the same photoreceptor. The phototransformation of this pigment results in two forms,P2andP4, to which physiological activity can be ascribed. The red and blue light affect different steps in a cyclical photoconversion. Calculated theoretical dose response curves are presented for such a model in agreement with the experimental

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03914.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY