摘要:

AbstractThe effect of desiccation on distribution of excitation energy between the two photosystems has been studied in the lichenCladonia impexaHarm., in the green algaTrebouxia pyriformisArchibald, isolated fromCladonia squamosa; and in the non‐lichen green algaScenedesmus obliquus, strain D3. The method used was to compare the low temperature fluorescence emission of samples equilibrated with air with different humidity prior to freezing in liquid nitrogen.Desiccation ofCladoniaandTrebouxiacaused a pronounced increase of the height of the far red fluorescence emission band, F 715, over the short wave bands, F685 and F697; the ratio between the two short wave bands remained essentially constant. Upon rewetting, these species regained normal fluorescence emission properties, indicating that they are desiccation‐tolerant.Scenedesmus, which was used as a desiccation intolerant species, also showed an increase of the far red fluorescence band over the two short wave bands upon desiccation, but the original fluorescence spectrum was not restored upon rewetting.These results are interpreted as showing that desiccation of tolerant species such asCladoniaandTrebouxiacauses a preferential energy distribution into photosystem I. We tentatively believe that desiccation induces conformational changes within the chloroplast thylakoids, thereby controlling distribution of energy between the two photosystems. Furthermore, this change in energy distribution may be of ecological significance as the mechanism by which desiccated lichens or algae avoid photo‐dynamic destruction of the photosynthetic apparatus when photosynthesis is inhibited under dry conditions. By a preferential distribution of absorbed energy into photosystem I, the organisms avoid the formation of strong, harmful oxidants in photosystem II when photosynthesis is inhibited. It is suggested that β‐carotene associated with the far red‐absorbing chlorophyllafraction of the reaction center antenna of photosystem I is the final sink for excess excitation energy in dry, desiccation‐tolerant liche

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03311.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractMetabolic changes in developingCuscuta campestrisYunck seeds were studied with respect to TCA‐soluble phosphate fractions, nucleic acids and the enzymes,viz, acid and alkaline phosphatase, neutral and alkaline FDPase, starch phosphorylase, α‐amylase ribonuclease, deoxyribonuclease and phytase. RNA and DNA contents increased steadily, and then remained stationary during the last two stages. The activities of all the enzymes studied increased with development with a sharp fall in the final stage. Interestingly, α‐amylase was present throughout the seed development. Phytic acid (16% of the total P) does not seem to function as phosphate reservoir, instead orthophosphate (13% of the total P) and nucleic acids (30% of the total P) may serve this f

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03312.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractDormancy and break of dormancy of tubers ofHelianthus tuberosusL. (Jerusalem artichoke) have been investigated in regard to the possibility that polyamines can control these processes. Polyamines were detected by the method of direct dansylation and abscisic acid was bioassayed using wheat coleoptile growth test. Arginine and glutamine, which are the main store nitrogenous organic compounds ofHelianthus tuberosustuber, decrease during the last phase of dormancy as well as abscisic acid; moreover the corresponding increase in polyamines (putrescine, spermidine and spermine) seems to be strictly related to the break of dormancy of tuber. The artificial break of dormancy induced by 2,4‐dichlorophenoxyacetic acid stimulates a great increase in polyamines, just evident within 15 min after activation, and a corresponding decrease in arginine and glutamine. The levels of polyamines, at 1 h of activation are sufficient to stimulate protein synthesisin vitr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03313.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractSeedlings ofPinus sylvestrisL. were grown under controlled conditions (temperature 20°C, photoperiod 17 h) at two irradiances, 8 or 40 W m‐2. Hypocotyl cuttings were excised and rooted at different irradiances in tap water solutions of indolebutyric acid (IBA). The fastest rooting and highest rooting percentage were obtained with cuttings from stock plants grown at 8 W m‐2and treated with 10‐5MIBA for 21 days. The concentration of 10‐4MIBA inhibited root formation. In comparable treatments rooting was always better in cuttings from stock plants grown at 8 W m‐2than in cuttings from stock plants grown at 40 W m‐2. The irradiance during the rooting period had only a minor influence on rooting. When cuttings from plants irradiated with 40 W m‐2were treated with 10‐5MIBA for 21 days the rooting percentage almost reached the same level as in untreated cuttings from stock plants given 8 W m‐2. In cuttings treated with IBA during the whole rooting period, rooting was depressed in comparison to untreated cuttings. Aeration of the 10‐4MIBA solution increased the rooting percentage, but aeration had no effect on untreated cuttings and on cuttings treated with lowe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03314.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractComplete separation of the steryl and wax esters in the subarctic mossDicranum elongatumwas achieved on MgO thin‐layer plates without any notable alteration of the acyl and alkyl moieties of the esters. Gas chromatography‐mass spectrometry of the hydrolyzed fraction showed that the sterols (campesterol, stigmasterol, sitosterol, cycloartenol, 24‐methylene cycloartanol and an unidentified sterol) were primarily esterified with unsaturated fatty acids 18:2 ω 6, 18:3 ω 3 and 20:4 ω 6. In contrast, the wax alcohols (l‐octadecanol, phytol and geranylgeraniol) were mainly esterified with saturated fatty acids with 16:0, 18:0 and 20:0 as major components. No great differences were found in the fatty acid pattern of the steryl esters between different portions of the shoot. Slight differences, however, were found in the proportions of ω 3 and ω 6 fatty acids. In the wax esters a clear decrease was found in the proportions of 18:0 and 20:0 acids with increased shoot age accompanied by a slight increase in the proportions of 14:0, 20:4 ω 6 and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03315.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effect of sulphite on ribulose bisphosphate carboxylase, extracted from needles ofPinus silvestrisL., was studiedin vitroat pH 8.15 and 25°C. 1 mMand higher concentrations of SO32‐inhibited the enzyme.The enzyme was activated either in the assay medium (2.5 – 20 mMHCO3,20 mMMgCl2) or in 10 or 20 mMHCO3‐and 20–25 mMMgCl2. Linear reciprocal plots of the activity versus the substrate concentration were obtained, when the HCO3‐concentration during activation was 4 mMor higher. When the enzyme was activated at high HCO3‐and Mg2+concentrations, the Km(CO2) wasc. 27 μM. With respect to HCO3‐. SO32‐inhibited the enzyme in a non‐competitive fashion. The inhibition was similar, whether SO32‐was present during activation or not. Apparently. SO32‐did not interfere with the binding of CO2and Mg2+at the activating site. The K1was 11–13 mMSO32‐. With respect to ribulose bisphosphate the inhibition was also noncompetitive.Similar results with respect to HCO3‐were obtained for spinach,Spinacia oleraceaL., which i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03316.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractStock plants ofHedera helixcv. Pittsburgh were grown in controlled environment rooms at four different irradiances (light intensities) 10, 22, 37 or 46 W m‐2PAR (photosynthetically active radiation). The root formation on single internode cuttings from these stock plants was observed in relation to length of the internodes and the position on the vine (topophysis). The analysis indicated that the root number was primarily dependent on internode length which in turn was dependent on irradiance to stock plants and topophysis. The irradiance of 37 W m‐2PAR was optimal for internode length and root number and the basal internode was the one which produced the greatest number of ro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03317.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractPhotosynthetic and anatomical parameters of leaves from the juvenile and adult part of an ivy plant (Hedera helixL.) have been determined and compared with each other. Light‐saturated net photosynthesis (per unit leaf area) was about 1.5 times higher in adult leaves than in juvenile ones. The lower photosynthetic capacity of juvenile leaves was caused by a lower stomatal and especially a lower residual conductance to the CO2‐transfer. This corresponds with anatomical features of the leaves,i.e.lower stomatal frequency, fewer chloroplasts per cell, and – most important – thinner leaves, as well as with a less efficient photosynthetic apparatus measured as Hill reaction of isolated broken chloroplasts and activity of ribulose bisphosphate carboxylase. No differences in the respiration in light (relative to net photosynthesis) and in the CO2‐compensation concentration could be detected between the two leaf types. These observed anatomical and photosynthetic parameters of the juvenile and adult ivy leaves resemble those reported for shade and sun leaves, respectively, although the leaves investigated originated from the same light en

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03318.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractStudies were conducted on effects of flooding for 15, 30, 60, and 90 days on morphological changes, stomatal aperture, water potential, and growth of seedlings ofMelaleuca quinquenervia, a species often planted for reclamation of swamps. Flooding rapidly induced formation of many hair‐like adventitious roots as well as a few thick adventitious roots that originated on the original root system. Some adventitious roots also formed on submerged portions of the stem.Melaleucaseedlings were very tolerant of flooding as shown by only slight reduction in dry weight increment of shoots after 30 days of flooding in stagnant water. Although flooding for 60 or 90 days significantly reduced dry weight increment of leaves, dry weight increment of roots was not inhibited by any flooding treatment, reflecting both degeneration of some of the original roots and compensatory growth of adventitious roots. On certain days flooding induced stomatal closure on both adaxial and abaxial leaf surfaces. Extensive production of adventitious roots and some stomatal reopening after a critical period of flooding appeared to be important factors in the flooding tolerance ofMelaleucaand are consistent with its aggressiveness and vigorous growth on wet site

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03319.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractAntibodies (rabbit) have been prepared against total stroma from isolated spinach (Spinacia oleraceaL. cv. Viking II) chloroplasts. These antibodies inhibited most of the aldolase activity present outside the chloroplasts in preparations of intact (80–95%) chloroplasts. They also reduced the amount of labelled fructose‐1,6‐bisphosphate found in the medium after14CO2fixation with such preparations. Both intact and broken chloroplasts were strongly agglutinated by the antibodies. The results indicate that the external fructose‐1,6‐bisphosphate was formed from excreted dihydroxyacetone phosphate by the action of aldolase and triose phosphate isomerase present outside the chloroplasts. The contamination of organelle preparations with free enzymes or enzymes adsorbed on the outer surface of the organelles is probably a general phenomenon. It is suggested that antibodies can be used as a tool to detect and selectively inhibit such contaminating enzyme a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb03320.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY