摘要:

AbstractThe cytokinin activity of the root exudate, the leaves, and the apices of vegetative and flowering white lupin plants (Lupinus albusL.) was investigated. The level of cytokinin activity in the root exudate decreased over the 11‐week experimental period. Four peaks of cytokinin activity were recorded in the root exudate of 8‐week‐old plants after fractionation on Sephadex LH‐20. Two of these peaks co‐eluted with zeatin and zeatin riboside. It is suggested that the remaining peaks represent nucleotide and glucoside cytokinins. The cytokinin levels in extracts of the mature leaves fluctuated slightly over the experimental period. Three peaks of activity co‐eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in extracts of mature leaves of 8‐week‐old plants. In the apices cytokinin activity could only be detected in the inflorescences of flowering plants. It would appear that cytokinins produced by the roots accumulate in the fully expanded mature leaves, but are utilized in the rapidly growing apical region and in young e

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01570.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe cytokinin content of the root exudate and leaves of fruiting white lupin plants (Lupinus albusL.) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence. Up to 8 weeks after anthesis the level of cytokinins in the root exudate increased. However, at 10 weeks after anthesis insufficient sap was produced for analysis. Cytokinins co‐eluting with zeatin and zeatin riboside were detected in the root exudate after fractionation on Sephadex LH‐20. The cytokinin levels in the mature leaves steadily increased up to 8 weeks after anthesis and thereafter remained relatively constant. Three peaks of activity, co‐eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in the leaf extracts. The level of glucoside cytokinins in the leaves was high at 8 and 10 weeks after anthesis. Paper chromatography of extracts of fruits collected at 2 weeks after anthesis indicated that as fruit development proceeded there was a build up of cytokinin in this region of the plant. It is suggested that, in the white lupin, the cytokinins translocated to the shoot are accumulated in the leaves and in the fruits and that it is only later when there is a considerable decrease in sap (10 weeks after anthesis) production that a decreasing supply of cytokinins leads to shoot senes

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01571.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe cytokinins in the pod wall and seeds of the white lupin (Lupinus albusL.) were investigated at 4, 6 and 8 weeks after anthesis. The level of cytokinin in the pod walls increased up to 8 weeks after anthesis, but then declined at 10 weeks. Fractionation on Sephadex LH‐20 shows that during the early stages of pod development cytokinin activity was associated mainly with substances co‐eluting with zeatin and zeatin riboside. However, in the later stages of pod wall growth an increase in activity was noted not only in these cytokinins but also in the cytokinins co‐eluting with the glucoside cytokinins. The level of cytokinin activity in the seeds decreased over the 10‐week experimental period. After fractionation on Sephadex LH‐20 four peaks of cytokinin activity were recorded in extracts of 6‐week‐old seeds. Two of these peaks co‐eluted with zeatin and zeatin riboside. The remaining peaks co‐eluted with the nucleotide and glucoside cytokinins. Only two peaks of activity co‐eluting with zeatin and zeatin riboside on Sephadex LH‐20 were recorded in 10‐week‐old seeds. Dihydrozeatin and its riboside also appear to be present in the seeds extracts. The significance of the quantitative and qualitative changes in the cytokinins of the seeds a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01572.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractInter‐organ control of greening in etiolated cucumber (Cucumis sativusL. cv. Aonagajibae) cotyledons was investigated. Four‐ or six‐day‐old excised or intact etiolated cucumber cotyledons were illuminated under aerobic conditions. Excised cotyledons without hypocotyl hooks produced chlorophyll without a prolonged lag phase and the rate of chlorophyll formation was not depressed if they were illuminated immediately after excision. If the excised cotyledons were incubated in the dark before illumination, chlorophyll accumulation at the end of 6 h of continuous illumination was remarkably lowered as the dark period lengthened, especially in 6‐day‐old cotyledons. The rapid loss of chlorophyll‐forming capacity of excised cotyledons during dark preincubation suggests a stimulatory effect of hypocotyls on the greening in cotyledons. The treatment of excised cotyledons with bleeding sap in the dark for 18 h resulted in the promotion of chlorophyll formation during subsequent continuous illumination. Partial fractionation of bleeding sap with organic solvents and paper chromatography indicates that the active substances showed the same behavior as cytokinins. These facts add weight to the hypothesis that cytokinins from roots flow into cotyledons and stimu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01573.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractIt has been reported in some cases that an increase in pCO2stimulates growth in diluted cell suspension cultures. Experiments have been designed to study the pattern of dark CO2fixation in sycamore cells grown in liquid suspension and to correlate this pattern with the culture growth phases. Comparisons were made between enzymatic activities, CO2incorporation, malic acid content during lag, logarithmic and stationary phases of growth. Malic enzyme (NADP‐dependent) was at its maximum activity during early logarithmic growth phase, when biosynthetic capacities were at the highest. Phosphoenolpyruvate‐carboxylase activity was strongly correlated with the ability of cells to fix CO2. Malic acid content decreased soon after transfer of the cells to a new medium and increased at the onset of stationary phase. Under optimal conditions, the CO2incorporation pattern did not change during growth, with an almost identical incorporation in the basic (amino acids) and acidic (organic acids) fractions. These observations have been discussed in relation to a possible effect of increased pCO2in the cell environm

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01574.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractCell suspensions ofDaucus carotaandHaplopappus gracilisand callus suspensions ofAllum cepavar.proliferumwere grown in media with and without activated charcoal. Differentiation occurred in thoseDaucusandAlliumcultures that contained charcoal. It was shown by mass spectrometry that the media without charcoal contained high amounts of phenylacetic acid andp‐OH‐benzoic acid (Daucus), 2,6‐OH‐benzoic acid (Allium) and benzoic acid, pelargonic acid and caprylic acid (Haplopappus), whereas the media with activated charcoal did not. It was also shown thatp‐OH‐benzoic acid had inhibitory effects on the embryogenesis inDau

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01575.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractMesophyll and bundle sheath chloroplasts were isolated by differential grinding from the leaves of two NADP‐ME C4plants,Setaria italicaBeauv. cv. H‐1,Pennisetum typhoidesS&H. cv. AKP‐2, and a NAD‐ME C4speciesAmaranthus paniculatusL. The mesophyll chloroplasts of C4plants possessed slightly lowerKmfor ADP and Pi than those of bundle sheath chloroplasts.The Hill reaction activities and noncyclic photophosphorylation rates of the bundle sheath chloropiasts fromS. italicaandP. typhoideswere less than one‐fifth of those by the mesophyll chloroplasts. But the bundle sheath chloroplasts ofA. paniculatusexhibited high rates of Hill reaction, cyclic as well as noncyclic photophosphorylation. The pigment‐ and eyiochrome composition suggested a relative enrichment of PS 1 in bundle sheath chloroplasts ofS. italicaandP. typhoides. The chain exists in both mesophyll and bundle sheath chloroplasts. As much as 35–52% of leaf chlorophyll was located in the bundle sheath chloroplasts. The photochemical activities of bundle sheath chloroplasts are significant though a major part of leaf photochemical potential is associated with the mesophyll

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01576.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe phase behaviour of smooth microsomal membranes from senescing cultures ofScenedesmus quadricaudahas been examined by wide‐angle x‐ray diffraction. The algae were grown in Bristol's medium at 22°C under continuous illumination. The transition temperature, taken to be the highest temperature at which crystalline (gel) phase lipid can be detected, increased with culture age from a low of 0°C for young cultures to a high of about 70°C for 140‐day‐old cultures. This indicates that for young cultures the membrane lipid is entirely liquid‐crystalline (fluid) at physiological temperatures, but as the cultures age portions of the lipid become crystalline. The increase in transition temperature showed a close temporal correlation with loss of chlorophyll and loss of protein per g dry weight, and can thus be construed as an index of senescence. The unsaturated to saturated fatty acid ratio of the membrane lipid, while fluctuating with culture age, did not show any consistent trend that could be related to the change in transition temperature. Thus the formation of gel phase lipid does not appear to be due to a change in fatty aci

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01577.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractWater transport through plant roots is determined by a single layer of cells, so that water passes through a plasmamembrane‐cytoplasm‐plasmamembrane system. The water transport shows an exponential relationship with temperature in two phases with an abrupt transition. The Arrhenius activation parameters logAandEare calculated for the two phases of water transport below and above the transition temperature. Between logAandEtwo linear and parallel relationships are observed, one for each phase of water transport. The difference of logAbetween these two relationships is a measure for a change in entropy in cell water structure at the transition temperature. The change in entropy was small (13.4 J · mol−1· K−1) in comparison to the difference in activation energyEfor water transport above and below the transition temperature. The role of the plasmamembrane and cytoplasm in determining the cell water structure is

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01578.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA series of experiments were carried out in order to elucidate whether acetylsalicylic acid (ASA) fed via petioles to beans could affect transpiration rate. In comparison with the water control it was found that a 10−3MASA reduces transpiration as much as 43%, a reduction equivalent to 5 × 10−5Mabscisic acid (ABA). Preliminary kinetics on the ABA, ASA and the water control on transpiration rate are presented and the results discu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01579.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY