摘要:

In vivo nitrate reductase (NR, EC 1.6.6.1.) activity was measured in leaves, branches and trunk of field‐grownAlnus glutinosa(L.) Gaertn. All of the assayed tissues enzymatically reduced nitrate with a decreasing activity [μmol NO2−(g dry weight)−1h−1] in the order: leaves>branch bark>inner branch tissues>trunk xylem. The NR activity of the various tissues of excised branches was inhibited by tungstate added to the transpiration stream. Part of the nitrate added to the feeding solution (0.2, 0.5 or 1 mMKNO3) of excised branches disappeared during its transport via the transpiration stream in the perennial tissues. This disappearance was enzymatic since it was decreased by tungstate.No evidence was obtained for the presence of nitrate in natural xylem sap nor for a significant correlation between nitrate content of soil and leaf NR activity. These results indicate that in the field‐grown black alder, the nitrate not reduced in the roots could be reduced in the perennial tissues of aerial parts. Since the leaf NR activity does not reflect the actual in situ nitrate reduction, the existence of a constitutive NR activity inAlnusleaves is

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03364.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The reasons for CO2release by some CAM plants during the light period were investigated by comparative gas‐exchange studies with three leaf‐succulent species,Kalanchoë tubifloraHamet,Sedum morganianumE. Walth. andSempervivum tectorumL.Sempervivumshowed net CO2output during the day at constant day‐night temperatures of both 15 and 25°C, whereasKalanchoëandSedumshowed no CO2release at this time at either temperature. Net nocturnal CO2uptake was markedly reduced at 25°C compared with 15°C inKalanchoëandSempervivum, while CO2was released at night at higher temperature bySedumif leaf/air vapour pressure difference was also increased.Values for intercellular partial pressure of CO2(piCO2) were calculated from leaf conductance and were characteristically lowest in the dark and highest in the light period. Maximum values of piCO2ranged from 264 Pa inSedumto 87 Pa inKalanchoë, but were somewhat lower than those reported from direct measurements of the gas phase in other CAM plants. Leaf conductance declined with increasing piCO2in all three species. Minimum values of approximately 0.2 mmol m−2s−1were observed at piCO2= 33 Pa inKalanchoëandSedum, with no further decrease at higher piCO2, implying that this largely represented the conductance of the cuticle. InSempervivum, however, leaf conductance declined more gradually, and was as much as 0.8 mmol m−2s−1at the highest observed values of piCO2. The cause of net CO2output in the light bySempervivumthus appeared to be lower stomatal sensitivity to CO2, resulting in relatively high leaf conductance even at times when piCO2greatly exceede

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03365.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Sixty‐seven hydroxyproline‐resistant (hypr) cell lines were selected from cell suspensions of a diploid potato (Solanum tuberosumL., clone H2578) after plating on 5 and 10 mMhydroxyproline (hyp). Resistant colonies were obtained with a spontaneous frequency of 2.9×10−6. No clear influence could be shown from treatment with N‐ethyl‐N‐nitrosourea (10 or 50 μM). Ninety % of the variant lines contained more proline than the wild type when cells were grown away from hyp for 1 month. Total free amino acid content was increased 2.2 to 6.8 times. When the lines were grown for another 2–5 months on non‐selective medium, the content of proline and other amino acids and hyp resistance decreased. After this period the values were, however, still substantially higher than in the wild type. When tested for growth on media with other amino acid analogues (azetidine‐2‐carboxylic acid and dehydroproline, analogues of proline; aminoethyl‐cysteine, analogue of lysine and 3‐fluorotyrosine, analogue of tyrosine) and on media with inhibitory concentrations of lysine + threonine. lines H4a and H4b4 were cross resistant to these compounds. When tested on media with inhibitory NaCl concentrations, variant lines H2a, H4a, and H6 showed better tolerance than the wild type. One variant cell line (H4a) was successfully regenerated into plants. Preliminary results showed an increased frost tolerance in the leaves of these plants (−4.5°C compared to −3°C for the wild type), accompanied by a higher leaf proline content. Callus initiated from leaves of the regenerated clones was more resistant to hyp than wild type callus, indicating that the variant t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03366.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Mature grain from 31 rice (Oryza sativaL.) cultivars grown in the same location was analyzed for soluble sugar content to determine quantitative differences in this parameter. Cultivar variation in caryopsis sucrose content was 4‐fold ranging from 15 to 59 μmol sucrose (g fresh weight)−1. Soluble reducing sugar ranged from 7 to 15 μmol hexose (g fresh weight)−1. Soluble sugar content was much greater in the outer part of the grain than in the endosperm. Caryopsis enzyme activities were measured in 8 cultivars having a range of grain sucrose content. No relationship between grain sucrose content of these cultivars and the level of enzymes of sucrose metabolism, glycolysis, and oxidative pentose pathway was established. Caryopsis respiration after 1 h of imbibition also was not related to the amount of soluble sugars available in the grain among these 8 cultivars. The results show that there are significant differences in the sugar‐accumulating capacity of the caryopsis of different rice cultivars. The detection of a fructose 2,6‐bisphosphate‐sensitive, PPi: fructose 6‐phosphate phosphototransferase (EC 2.7.1.90) in the endosperm suggests the presence of a regulatory mechanism for sucrose/starch partitioning established in othe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03367.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The growth of a supernodulating, nitrate‐tolerant soybean [Glycine max(L.) Merr.] mutantnts382 (nitrate‐tolerant symbiosis) was compared to that of its wild‐type parent, cv. Bragg, over the first 50 days after sowing. Plants were grown either inoculated in the absence of an external nitrogen source or uninoculated in the presence of 5 mMKNO3. For both treatments,nts382 growth up to 13 days after planting was faster than that of cv. Bragg. Thereafter, supernodulation of inoculatednts382 occurred and growth of cv. Bragg was faster; shoot and root dry weight increments and leaf area were greater in cv. Bragg, but the N content ofnts382 was higher. Relative growth and net assimilation rates were lower innts382, which had faster shoot and root respiration rates. Shoot growth of uninoculated plants was similar for both mutant and wild‐type but roots ofnts382 were slightly smaller than those of cv. Bragg. Total plant N content was similar in uninoculated cv. Bragg andnts382 but the latter had a higher leaf N content. Early lateral root formation (prior to nodule emergence) was greater innts382 regardless of whether rhizobia or KJNO3were present. We conclude thatnts382 has some inherent differences from its parent but that supernodulation significantly retards plant

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03368.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

A transient CO2burst from seedlings of some plant species was observed after a rapid temperature decrease. The magnitude of the CO2release depended on initial temperature, oxygen concentration and light intensity. To obtain a maximal value of CO2release, the temperature had to decrease by more than 8°C. The phenomenon was detected only in the light, and was confined to C3species. It was inhibited by low oxygen concentration, indicating its possible connection with photorespiration

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03369.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Regulation of nitrate reductase (NR, EC 1.6.6.1) by oxygen concentration and light was studied in segments of oat (Avena sativaL. cv. Suregrain) leaves, using the in vivo nitrate reductase assay. The activity of NR decreased after excision in either light or darkness; the addition of cycloheximide prevented this decrease. Treatments that increased tissue permeability (anoxia, Triton X‐100) also increased NR activity. There was in general less NR activity in the light than in the dark and also less under aerobic (21–100% O2) than under anaerobic (0.3% O2) conditions. Treatments with antioxidants improved the activity in the light, but only at high O2levels (21–100% O2).The results suggest that NR may be regulated by inhibitory proteins synthesized in either light or darkness, by permeability changes and by light‐induced oxidations that occur when O2is present. Oxygen may control the activity by stimulating the synthesis of inhibitory proteins in the light and in the dark and by promoting oxidation of SH‐groups in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03370.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The short‐term effects ofp‐chloromercuribenzenesulphonic acid (PCMBS) on the transmembrane potential difference (PD) of broad bean (Vicia fabaL. cv. Aguadulce) cotyledon cells and on sugar beet (Beta vulgarisL. cv. Klein E.) leaf cells were studied by the electrophysiological method. These effects were compared with that of the permeant thiol reagents N‐ethylmaleimide and HgCl2. N‐Ethylmaleimide and HgCl2markedly and rapidly depolarised the PD of all the material studied, while PCMBS caused either a slight depolarisation (cotyledon cells) or no depolarisation (leaf cells) during the first 30 min of treatment. In cotyledons, PCMBS markedly inhibited sucrose uptake (89%) and the sucrose‐induced depolarisation associated with the proton‐sucrose symport (67%), while it decreased the proton‐motive force only marginally (7%). It is concluded that during short treatments (30 min or less). PCMBS inhibits sucrose uptake directly by blocking the sucrose carrier, and not the proton pump. For longer treatments, indirect effects canno

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03371.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Gas chromatography‐mass spectrometry evidence is presented for the presence of both phenylacetic acid (PAA) and 3‐indoleacetic acid (IAA) in vegetative and fertile tissues of the sporophyte of the ostrich fern [Matteucia struthiopteris(L.) Todaro]. 3‐Indolepropionic acid, tryptamine and 3‐indoleacetonitrile were not found in tissue extracts, although small amounts of 3‐indolebutyric acid and tryptophol may have been present. PAA was present in amounts higher than those found in flowering plants, while LAA levels fall within the angiosperm range. The levels of both auxins were higher in the younger vegetative tissues than in mature vegetative or fertile pinnae. Recent evidence for the occurrence of angiosperm growth hormones in ferns is

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03372.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The vegetative mycelium ofSphaerostilbe repensBerkeley and Broome (strain CBS 275‐60) gives rise, within 48 h, to aggregated organs composed of coremia and rhi‐zomorphs. Developmental changes in polypeptide patterns were studied by one‐ and two‐dimensional polyacrylamide gel electrophoresis after cells had been induced to undergo synchronized differentiation. One‐dimensional gel electrophoresis revealed only minor changes during the morphogenesis. Of the 300 polypeptides resolved by two‐dimensional gel electrophoresis, nearly 12% either increased or decreased during coremium and rhizomorph differentiation. Some polypeptides appeared to be unique to one or the other of the cell preparations and represented apparent qualitative differences. During the first 24 h of differentiation, about 20 polypeptide spots appeared, 6 were enhanced, 4 were reduced and 32 disappeared. Over the next 24 h changes in the population of proteins were less marked: 14 new proteins were revealed and 9 increased in intensity while 15 declined and 9 were no longer detectable. Five proteins which were present at a significant level only during the first stages of differentiation, may therefore, putatively be designated as aggregation‐specific

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03373.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY