摘要:

AbstractAs a continuation of a study of the molecular events surrounding the establishment of a mature root apex, changes in the pattern and specific activity of the isoenzymes of aminopeptidase (AmP), esterase (EST), glucose‐6‐phosphate de‐hydrogenase (G6PD) and glutamic‐oxaloacetic transaminase (GOT) were investigated during the early germinative growth of the Allium radicle tip.Polyacrylamide disc gel electrophoresis revealed a total of 9 EST fractions. A shift in pattern and reactivity characteristic of pre‐emergence to those characteristic of post‐emergence was demonstrated.G6PD electropherograms displayed 5 isoenzyme bands. Relative specific activity analyses indicated that this enzyme may be more important during the very early stages of germination.Only quantitative differences were noted in the 3 AmP isoenzymes detected. The progressive increase in AmP isoenzyme activity during the period of maximal protein body degradation suggested a role for these exopeptidases in the degradation of reserve proteins.The 3 isoenzyme bands of GOT exhibited only quantitative changes during germination. Parallel increases in the quantity of soluble protein and GOT specific activity suggest that this isoenzyme is involved in the onion's nitrogen metabolism during

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03556.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractNyctinastic closure ofAlbizzia julibrissinpinnules is inhibited by 5 × 10−2Methylenediaminetetraacetic acid. At least two hours of incubation are required for maximum inhibition and destruction of the phytochrome effect.Concentrations of 10−3to 10−5Mnaphthaleneacetic acid reduced the nyctinastic closure of pinnules but not the phytochrome response. Similar results were obtained with indoleacetic acid and gibberellic acid. No appreciable differences in pinnule movements could be attributed to pH. Chelation or the inhibition of ion transport resulting in, or caused by, changes in membrane permeability are suggested as possible mechanisms involved in these e

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03557.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractExcision of the embryonic axis prior to 3 1/2 days of germination in the dark followed by 8‐h of light decreased the total chlorophyll content of cucumber cotyledons but not squash cotyledons. Benzyladenine stimulated the accumulation of chlorophyll in the cotyledons of intact embryos and excised cotyledons in both cucumber and squash. Gibberellic acid had no effect. Atrazine inhibited chlorophyll formation in excised squash cotyledons. Benzyladenine also increased the carotenoid and xanthophyll content in the cotyledons from intact squash seedlings.The results suggest that pigment synthesis in cotyledons may be controlled by a number of substances produced in the embryonic axis and that cytokinin‐like benzyladenine can simulate the action of one of t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03558.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractSeveral transpiration suppressants, (phenyl mercuric acetate, Tag 16 (polyethylen emulsion) R14‐poly (ethylene adipate) 4–4 Diphenylmethan diisocyanate), which are known to either close stomata or form thin films on leaves, were sprayed on citrus and grapevine seedlings. Water vapor and carbon dioxide exchange of single leaves were measured by means of infra red gas analyzer and L1C1 hygrosensors. Theeffects of the chemicals were evaluated by analyzing net photosynthesis, transpiration, mesophyll resistance to CO2compensation concentration and respiration. All the chemicals tested increased either mesophyll resistance or CO2compensation point to various degrees. It is concluded that none of the chemicals tested acted solely on epidermal resistance. All chemicals reduced photosynthesis, but the ratio of photosynthesis to transpiration increased in most cases in grapevine but not in citrus. Different chemicals acted differently on citrus and grapevine. The method of analysis used enabled us to evaluate separately the relative effect of a chemical on mesophyll resistance and respirat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03559.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractEvidence is given that a selective light‐pretreatment of the embryonic axis exerts a deep influence on the greening in primary leaves of 8‐day‐old etiolated bean seedlings (Phaseolus vulgariscv. Limburg). After a subsequent dark incubation of sufficient length and a final exposure of the entire plants to continuous illumination the lag phase of chlorophyll synthesis is completely removed. In particular the highly meristematic hook tissue seems to be responsible for this light effect. Lengthening of the dark period following pre‐irradiation increased the capability of chlorophyll production in the main white light period, reaching its maximum after about 12 hours of darkness. The period of dark incubation for elimination of the lag phase is considerably longer in plants with shielded leaves than the length of the lag phase in etiolated seedlings of the same age, exposed entirely to continuous light. This difference may be explained by the synergistic effect between leaves and embryonic axis. Evidence for this interorgan cooperation is given by experiments with a selective light‐pretreatment of leaves and embryonic axis. After a 5 min pre‐exposure to white light of whole plants the leaves of some of the plants were shielded and these plants received a further pre‐illumination of 2 hours on their embryonic axis. In all the pre‐irradiated, etiolated plants the lag phase of chlorophyll synthesis was eliminated during the main white light period, following a dark incubation of 2 hours. Additional and preferential light activation of the embryonic axis during the pretreatment had no significant effect on chlorophyll production during the white light illumination after a 2 hours dark incubation, but resulted in a lower yield of chlorophylls after 18 hours dark incubation compared to the white light controls, receiving no selective light‐pretreatment on the embryonic axis. From our results we can decisively conclude that a simultaneous light‐pretreatment of both, leaves and embryonic axis, is more effective and beneficial for building up a capacity of chlorophyll synthesis in the leaves than either a selective light‐pretreatment of the embryonic axis alone or a simultaneous pre‐illumination of leaves and embryonic axis, immediately followed by an additional preirradiation of the embryonic axis. Therefore, we think that several photoactive sites are involved in de‐etiolation processes of intact, etiolated seedings. Light activation of the embryonic axis stimulates the development of this organ and contributes to the greening processes in the leaf. At the same time, by irradiating the leaf, light activates the photo‐sensitive site in the leaf itself, which also develops a capacity for chlorophyll synthesis. Both photo‐acts are cooperative, explaining the enhanced chlorophyll production. Additional pre‐irradiation of the embryonic axis after a short illumination of whole plants favours its own development and reduces the synthetic capacity of the leaf. A prolonged far‐red pretreatment induces qualitatively the same response as white light. We assume that these effects on lag phase removal and chlorophyll production, induced in etiolated, primary bean leaves by selective irradiation of the embryonic axis, is a phytochrome‐mediated process. Our results indicate a transmission of light‐indu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03560.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThere was greater incorporation of [2−14C] acetate and of [6−14C] glucose into phosphoglycerides than into triglycerides, of 1 1/2, 2, 3, 4 and 6 day old mycelial sample of the fungus Glomerella cingulata. Maximum incorporation into both classes of lipids occurred in young mycelial samples (2 to 3 days of age) which had a high content of total nitrogen. The five sets of mycelial samples all contained somewhat larger quantities of phosphoglycerides than triglycerides, and changes in content of both classes of lipids were similar in pattern to changes in content of total nitrogen. Incorporation, accumulation and total nitrogen of the mycelial samples, decreased at 4 days but increased again by 6 days. The apparent turnover of the triglycerides and phosphoglycerides was qualitatively similar although there was greater apparent turnover of phosphoglycerides than triglycerides; the similarity in patterns of apparent turnover was inferred to be a consequence of acyl exchange between labeled and unlabeled triglycerides and phosphoglycerides. There was greater incorporation of [2−14C] acetate into the acyl than into the glyceryl moieties of both classes of lipids but greater incorporation of [6−14C] glucose into the glyceryl than acyl moieties. With both precursors, the glyceryl and acyl moieties of the phosphoglycerides were more heavily labeled than corresponding moieties of the trigly

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03561.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe uptake and translocation of59Fe applied to leaves ofZea maysL. is studied with special reference to the effect of dimethylsulfoxide (DMSO).59Fe is deposited on corn leaves as droplets of solution of ferrous sulfate or ferric nitrate (1 mM. The uptake of59Fe is affected by the associated anion; the penetration is more important with the nitrate than with the sulfate. The translocation of59Fe from the treated part during 24 hours is very low in all the experiments. The exsorption of59Fe taken up, from the site of application in different solutions (FeSO4, 7H2O; EDTA Na) concerns only a low percentage of59Fe present in the treated part. DMSO (0.5 and 1 %) increases the uptake but not the translocation of59Fe applied as sulfate; it seems to have no effect when iron is applied as nitrate. The increase during 24 hours reaches between 32 % and 53 % in seven experiments with sulfate. The effect also appears in an experiment conducted during four weeks, with several applications of ferrous sulfate during this time. This effect of DMSO is discussed: it is mainly explained by the great hygroscopicity of this solvent, therefore the effect would in part depend on the solubility of salts in concentrated DMSO and of the climatic conditions: relative humidity and temperature of the air.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03562.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractSupplying nitrate to N‐depleted wheat seedlings (Triticum vulgarecv. Knox) stimulated the uptake and translocation of both83Sr and45Ca. Since the increase in45Ca accumulation was greater, the85Sr/45Ca ratio in the plant tissue was decreased. Nitrate had relatively little influence on the amount of the divalent cations and85Sr/45Ca ratio in the exchangeable fraction on the root surfaces, whereas it greatly increased the uptake into root tissue and translocation to shoots. The increase in percent transported to shoots occurred largely in the period of most rapid nitrate uptake.A split root study indicated that nitrate was ineffective when it was supplied to a different portion of the root system than that exposed to85Sr and45Ca. Nevertheless, ammonium and urea also increased the translocation of the two cations, indicating that the effects of nitrate could not entirely be ascribed to a direct effect of the nitrate anio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03563.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03564.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY