摘要:

Gibberellins A1(GA1), GA4, GA9, GA19, and GA20were identified in extracts of leaves ofBegonia x cheimanthaEverett cv. Nova (Christmas or Lorraine Begonia). GA‐like substances were purified by reverse phase and normal phase high performance liquid chromatography (HPLC) and detected by Tan‐ginbozu dwarf rice bioassay and binding to antibodies raised against GA1, GA4and GA9. The final identifications were made by gas chromatography—mass spectrometry (G

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05424.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The activity levels of enzymes of aromatic amino acid biosynthesis respond to changing physiological states of growth, as illustrated by results obtained from suspension‐cultured cells ofNicotiana silvestrisSpeg. et Comes line ANS 1 (2N=24). The experimental system provides a foundation for interpretations about overall regulation of enzyme levels in relationship to growth physiology. Levels of activity for shikimate dehydrogenase (EC 1.1.1.25), prephenate aminotransferase and arogenate dehydrogenase were followed throughout a growth cycle obtained by a conventional subculture protocol. Enzyme date were also obtained from cell cultures maintained in continuous exponential growth for greater than 10 generations (EE cells). Both shikimate dehydrogenase and prephenate aminotransferase exhibited elevated stationary‐phase levels of enzyme, much of which was carried over into a subsequent subculture. At least 4 generations of exponential growth were required before diminution of the latter two enzymes to the levels characteristic of truly exponential‐phase growth (EE cells) occurred. This is reminiscent of the overall behavior of 3‐deoxy‐D‐arabino‐heptulosonate 7‐phosphate (DAHP) synthase (EC 4.1.2.15), specifically attributed to the properties of the cytosolic isozyme species (DAHP synthase‐Co). Elevation of arogenate dehydrogenase also occurred in stationary‐phase cells, but diminished rapidly during lag phase to reach the level charact

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05425.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The earlier observation that the fluorochrome sulphorhodamine G selectively enters cells of the extended bundle sheath system (paraveinal mesophyll) of soybean leaves from the transpiration stream, is extended to all the 26 species of legumes so far tested. The species examined were selected to include the three types of the system previously identified: Type 1 with complete systems, Type 2 with attenuated systems, and Type 3 with ordinary bundle sheaths. In Type 3 the dye selectively entered the bundle sheath cells. The hypothesis that the entry of the dye to a cell is caused by local low external pH, which suppresses its ionization, is confirmed by tests of the response of sulphorhodamine uptake to changing external pH, and of the inhibition of uptake by the ionophore dinitrophenol. An extension of this hypothesis identifies the local pH gradient as an energy source driving influx pumps to scavenge solutes from the transpiration stream and store them in special cells. It is proposed that this may be broadened to include many legumes. The activity of the proton extrusion pumps in this storage network is shown to be correlated with the flowering and fruiting of soybean, showing high activity before flowering, and disappearing during pod formation when nitrogenous materials are exported from the network.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05426.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The fluorescent probe sulphorhodamine G (SR) has been previously used as an indicator of low extra‐cellular pH and, by inference, of proton extrusion activity in living leaves. In legumes the SR uptake and proton extrusion was characteristic of the extended bundle sheath system (EBS) or paraveinal mesophyll, composed of bundle sheath cells and the related network of bridging cells between veins. This system has been identified as a site of temporary storage of amino carbon in soybean. A tree species.Populus deltoidesBartr. ex Marsh, was known both to have the EBS system in its leaves and to carry organic nitrogen in its xylem sap. It is now shown thatP. deltoidesalso accumulates the SR probe in the EBS system. This association has been explored in 8 other broad‐leaved tree species. Seven of the 8 species have EBS systems and accumulate SR in them in early summer. The 8th species,Tilia americanaL. has no EBS system and shows weak SR accumulation. The capacity to accumulate SR (and by inference to scavenge solutes from the transpiration stream) disappeared in all species at various stages in late summer. In two species, in addition, SR accumulation is interrupted for several weeks during fruit growth. It is proposed that EBS systems will be found in many dicotyledonous leaves, and will be found to scavenge solutes, especially organic nitrogen, from the xylem

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05427.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The growth, mineral and shoot and root CO2exchange of wheat plants (Triticum aestivumL. cv. Courtot) cultivated in growth chambers have been studied during the complete life cycle. The life cycle could be divided into 4 periods according to the patterns of CO2exchange: exponential increase, linear increase, stabilization and decline of photosynthesis. These patterns are analysed in relation to light interception, tillering, competition between plants and ageing of the leaves, all of which constitute successive limiting factors. Root metabolism seemed to be subordinated to the demand of the shoot for minerals. Ion uptake from the nutrient solution was particularly pronounced in young plants, which were higher in minerals and nitrogen than older ones. The ratios of K and P uptake varied with plant age, and the charge balance in ion exchange was equlibrated by H uptake. Rhythmic patterns appeared in all exchanges and varied with plant age. The highest amplitude of rhythm was found in root respiration. After taking the losses due to respiration and photorespiration into account, the maximum rate of photosynthesis approached the theoretical value calculated from the light energy absorbed.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05428.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The long‐term role of photorespiration was investigated by comparing growth, development, gas exchange characteristics and mineral nutrition of a wheat crop (Triticum aestivumL. cv. Courtot) cultivated in a culture chamber during a life cycle, either in 4% O2or in normal O2Low O2pressure reduced photorespiration, but CO2was controlled so that net photosynthesis remained the same as in the control crop. The growth and development of the low O2crop was slowed down. Ear appearance was 16 days late, but the rate of tillering was the same as in the control and was maintained longer so that the final number of tillers was doubled. Pigment, ribulose bisphosphate carboxylase (EC 4.1.1.39) and soluble sugar contents were similar. The response of photosynthesis to CO2and O2was not appreciably changed by the low O2treatment. There was almost no seed formation, and the senescence of the leaves was delayed. It appears that in non‐stress conditions most of the photorespiration can be suppressed without damage to the photosynthetic apparatus. Retardation of development and inhibition of reproduction are likely due to other effects of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05429.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Electrophoretograms of turions of dioeciousHydrilla verticillata(L. f.) Royle, run under non‐denaturing conditions, had a major complex protein band at Rf0.45 (7.5% acrylamide). Extracts of monoecious plants under similar conditions had major bands at Rf0.43 and 0.45. The polypeptides which comprise these bands were partially purified and characterized. The major protein fraction in extracts of dioecious turions had a molecular mass of 58 kDa on gel permeation chromatography. Electrophoresis of this fraction under denaturing conditions in the presence of sodium dodecyl sulfate indicated principal bands with molecular masses of 58 and 57 kDa. Extracts from turions of the monoecious biotype had major bands at 59 and 55 kDa after electrophoresis under denaturing conditions.Antisera were raised against the proteins from the dioecious turion at Rf0.45 after electrophoresis under non‐denaturing conditions. When blots of gels run under non‐denaturing conditions were probed with these antisera, a complex band was seen at Rf0.45 for extracts of the dioecious biotype, while bands were observed at Rf0.43 and 0.45 for the monoecious extracts. After electrophoresis under denaturing conditions, immunoreactive bands were noted at 58 and 57 kDa or 59 and 55 kDa in extracts of dioecious and monoecious turions, respectively.Extracts of leaves and stems ofH. verticillatahad detectable amounts of immunoreactive proteins, regardless of photoperiod, hence turion production. Related plants with the aquatic habit had immunoreactive proteins in their leaves and organs of perennation [Elodea canadensisMichx.,Elodea nuttallii(Planch.) St. John, andEgeria densaPlanch.,Potamogeton nodosusPoir. andP. pectinatusL.], but the presence of these proteins was not noted in other plants (Zea maysL.,Allium cepaL.,Spinacia oleraceaL.,Lemna gibbaL., orSolanum tuberos

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05430.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In the southeastern part of the Netherlands many Scots pine (Pinus sylvestrisL.) trees show signs of yellowing. To investigate whether there is a relation between this phenomenon and the high ammonium deposition, needle and soil samples were analyzed. Soil samples from the discoloured forests contained more extractable nitrogen than samples from healthy stands, whereas differences in pH values were small. Needles from yellow trees had higher levels of total nitrogen than needles from green trees as well as severe imbalances of Mg, K+and P relative to N. The amount of leaf pigments was substantially lower in needles of the diseased trees, but they contained much higher quantities of free arginine, which accounted for a major part of total nitrogen. This may be an indication of a severe nitrogen overload. The linkage between this excessive nitrogen nutrition and the observed process of yellowing is discussed.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05431.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Median and lateral seeds ofSalicornia europaeaL. were separately analysed for their sizes and nutrient reserves. The mean air‐dry weight of a single median and lateral seed was 0.31 and 0.25 mg, respectively. The composition as well as the concentration of the nutrient reserves were similar in both seed types. The bulk of the cations was derived from K+, followed by Mg2+, Na+and Ca2+. The chloride content was somewhat higher than the sodium content, and phosphate was equalled by acid soluble Ca2+and Mg2+. Starchy compounds and sucrose were present in equal amounts, each of them accounted for about 50% of the carbohydrates. Glucose and fructose were less than 1%. Protein‐nitrogen (ethanol‐insoluble N) was about 34 g (kg dry seeds)−1. About 7 g (kg dry seeds)−1was ethanol‐soluble nitrogen, of which 10% was derived from amino acids. The total lipid content was more than 290 g (kg dry seeds)−1, 65% were calculated to be glycerides. More than 90% of the fatty acids consisted of linoleic and oleic acids, the majority (72%) of which was

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05432.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A method is described to determine germination by blue‐light excited red fluorescence in the positively photoblastic spores ofDryopteris paleaceaSw. This fluorescence is due to chlorophyll as evidenced from 1) a fluorescence‐emission spectrum in vivo, where a bright fluorescence around 675 nm is obtained only in red light (R)‐irradiated spores and 2) in vitro measurements with acetone extracts prepared from homogenized spores. Significant amounts of chlorophyll can be found only in R‐treated spores; this chlorophyll exhibits an emission band around 668 nm, when irradiated with 430 nm light at 21°C.Compared to other criteria for germination, such as swelling of the cell, coat splitting, greening, and rhizoid formation, which require longer periods after induction for their expression, chlorophyll fluorescence can be used to quantify germination after two days. This result is confirmed by fluence‐response curves for R‐induced spore germination; the same relationship between applied R and germination is obtained by the evaluation with the epifluorescence method 2 days after the light treatment as compared with the evaluation with bright‐field microscopy 5 days after the inducing R.Using this technique we show for the first time that Ca2+contributes to the signaltransduction chain in phytochrome‐mediated chlorophyll synthesis in spores ofDry

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05433.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY