bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biosynthesis and root exudation of citric and malic acids in phosphate‐starved rape plants
Authors: HOFFLAND ELLIS , VAN DEN BOOGAARD RIKI , NELEMANS JAAP , FINDENEGG GÜNTER 
Published: September 2010

summaryRape (Brassica napus L.) plants are efficient users of rock phosphates. This has been ascribed to the excretion of malic and citric acids from the roots during phosphorus deficiency, resulting in a decrease of the pH in the rhizosphere and a consequent solubilization of the rock phosphate. In this paper the biosynthesis and excretion of organic acids were investigated, partly by comparing physiological reactions to P deficiency of rape with those of an inefficient user of rock phosphate from the same family, hedge mustard (Sisymbrium officinale Scop.). In the leaves of both species, both citrate levels and phosphoenolypyruvate carboxylase were nearly doubled in P–deficient plants, and the citrate/sugar ratio in the phloem exudate into EDTA solution was doubled as well.After exposure of the shoots of rape plants to 14CO2 in the light, the specific activities of citrate in the root and in the nutrient solution were ten times higher than those of malate, and also much higher than the respective activities of citrate in P–sufficient controls. It is suggested that citrate produced in the leaf is exported to the roots, where it is accumulated in the excretion region. Malic acid which is prevailing in the exudate is probably newly–synthesized within the excreting root segment. When no phosphate is supplied, this excretion zone is located 1–2 cm behind the root tips. However, when rock phosphate is applied locally this zone shifts along the root to that part which is in direct contact with the rock phosphate particles. No accumulation and excretion of organic acids could be observed with the roots of P–deficient Sisymbrium.
Evidence against a role for phytochelatins in naturally selected increased cadmium tolerance in Silene vulgaris (Moench) Garcke
Authors: DE KNECHT JOOP A. , KOEVOETS PAUL L. M. , VERKLEIJ JOS A. C. , ERNST WILFRIED H. O. 
Published: September 2010

summaryThe production of phytochelatins in roots of both cadmium–sensitive and cadmium–tolerant plants of Silene vulgaris (Moench) Garcke in response to Cd supply was recorded over a 7–day growth period. At the same level of Cd, sensitive plants produced more phytochelatins than tolerant ones. In sensitive roots this higher production of PCs was associated with a higher Cd content within one day. From the third day, however, Cd contents were similar, but the difference in PC production persisted. Exposure to buthionine sulphoximine strongly inhibited the production of phytochelatins in roots during cadmium treatment in both sensitive and tolerant plants, but only affected root growth of sensitive plants. Sensitive plants exhibited a higher Cd uptake, which was manifested in a higher Cd accumulation in the shoot. It is concluded that differential cadmium tolerance mechanism in Silene vulgaris is not due to differential production of phytochelatins.
Carnivory in pitcher plants of the genus Heliamphora (Sarraceniaceae)
Authors: JAFFE KLAUS , MICHELANGELI FABIÁN , GONZALEZ JORGE M. , MIRAS BEATRIZ , CHRISTINE RUIZ MARIE 
Published: September 2010

summaryField studies of Heliamphora nutans Benth., H. heterodoxa Steyerm., H. minor Gleason, H. ionasii maguire and H. tatei Gleason in the Guayana Highlands of Venezuela, show that the last named species is a true carnivore, possessing all of the following traits: attraction of prey through special visual and chemical signals, trapping and killing of prey, digestion of prey through secreted enzymes, presence of commensals, presence of wax scales aiding in the capture of prey, and absorption of nutrients. The other species possess all traits except they seem neither to secrete proteolytic enzymes nor produce wax scales. The pattern of the carnivorous syndrome among Heliamphora species suggests that the carnivorous habit has evolved in nutrient–poor habitats to improve the absorption of nutrients by capturing mainly ants and only H. tatei further evolved mechanisms for rapid assimilation of organic nutrients and for capturing a variety of flying insects. The carnivorous traits are lost in low light conditions, indicating that nutrient supply is limiting only under fast growth.
Vegetational succession, acidification and allogenic events as recorded in F landrian peat deposits from an isolated Fenland embayment
Authors: WHEELER A. J. 
Published: September 2010

summaryPalaeoecological investigations have been carried out at Wood Fen including pollen and macrofossil analysis. The vegetational history is related to other Fenland sites and is dated by radiocarbon. The base of the vegetational record is dominated by Quercus, Tilia, Corylus/Myrica, Taxus and Ulmus pollen, envisaged as components of the pre‐fen woodland. A rise in the water table resulted in the accumulation of peat which has been correlated with the deposition of a marine/brackish clay (‘fen clay’) in the west of the basin dated at between 4150 BP and 3800 BP. A rise in the acidophilous flora occurred at 3615 BP represented by a change from monocotyledonous to Sphagnum peat and subsequent colonisation by Pinus. Loss–on–ignition data suggests that the colonization by pine was interrupted by a brief flooding episode and subsequently terminated by a major rise in the regional water level with an inferred date of between 3300 BP and 3000 BP, based on comparison with other sites. The high water table probably prevented development to raised bog although an acidophilous flora persisted until a return to eutrophic alder carr at the top of the profile.The nature of the autogenic succession and acidification is discussed and the chronostratigraphic relationships of allogenic influences are considered.
Holocene vegetation history of Flinders Island
Authors: LADD P. G. , ORCHISTON D. W. , JOYCE E. B. 
Published: September 2010

summaryTwo swamp sites on Flinders Island in Bass Strait provide evidence of vegetation cover for the period 10000 BP to present. Steppe vegetation in which Compositae Liguliflorae taxa and chenopods were important was present on the Flinders Island part of the Bassian Isthmus during the earliest part of the record. However, it was replaced by eucalypt forest or woodland with a grassy understorey and some shrubs as sea level rose to form the present island by 6000 BP. The eucalypt dominated vegetation became less important about 940 BP when Callitris became prominent until very recently. This change may be related to a drier climate.Flinders Island is one of the few sites in Australia where humans were absent for an extended time (c. 4700 to 200 BP) during the Holocene. There is no particular indication of pollen or charcoal changes which can be related to the disappearance of humans from the island. However, at Killiecrankie Swamp the arrival of Europeans 200 yr ago probably caused the increased charcoal input to the swamp sediments and the vegetation change observed. Likewise Middle Patriarch Swamp records changes due to clearing and swamp drainage in the most recent times. The fact that the swamp deposits contain charcoal and pollen, together with the density of swamps on the eastern side of the island means the area is very favourably placed to provide detailed information on firing regimes unaffected by humans, in a sclerophyll vegetation very similar to that in large areas of southeastern Australia.In the light of the pollen evidence from this study and that from other southeastern mainland and Tasmanian sites it is suggested that the apparent prominence of Casuarina in the southwest of Victoria and southeast of South Australia during the early Holocene was due to local soil factors and drier climate. Later changes in soil and climate led to a decrease in Casuarina and increase in Eucalyptus.
Evolutionary origins and natural functions of fructans – a climatological, biogeographic and mechanistic appraisal
Authors: HENDRY GEORGE A. F. 
Published: September 2010

SUMMARYGenes for fructan synthesis arose in plants on several occasions ranging from the Cambrian (in Dasycladales‐like algae), the late Devonian (in Jungermannialian liverworts) through to the Tertiary (six orders of angiosperms, including the evolutionarily advanced Poales and Asterales). The widespread occurrence of fructan processing in eubacteria may hove been in response to the rapidly increasing availability of fructan in the angiosperms and the expansion of grass‐eating mammals in the mid‐Tertiary. The origin mid evolution of the majority of fractan‐rich angiosperm families, from fossil evidence, occurs in a relatively narrow window from the Oligocene to the mid‐Miocene (30–15 Ma ago). These epochs coincide with the development in several regions, in most continents, of seasonal rainfall and more prolonged periods of water shortage. The replacement of tropical and temperate forests by a fructan flora in drylands and semi‐arid to arid regions was world‐wide and accounts for tile rapid expansion of fructan‐rich families in the mid‐Tertiary and again in drier phases of the early Holocene. The natural distribution of the contemporary fructan Mora confirms the association of fructan‐rich families with temperate through to sub‐tropical regions with seasonal or more sporadic rainfall and not with regions of low temperatures. It is argued that the natural function of fructan is in maintaining growth during periods of limited water availability. The function of fructan as a vacuolar and soluble carbohydrate in osmoregulation and in Growth by cell inflation rather than temperature‐dependent cell division is given as the most likely explanation for the global success of the 15% of the angiosperm flora which store fructan as a principal reserve carbohydrate.
Purification and properties of an invertase with sucrose: sucrose fructosyltransferase (SST) activity from the roots of Cichorium intybus L.
Authors: VAN DEN ENDE WIM , VAN LAERE ANDRÉ 
Published: September 2010

SUMMARYAn invertase was purified From Cichorium intyhbus L. roots by a combination of ammonium sulphate precipitation. Concanavalimn A affinity chromatography, anion exchange chromatography and gel filtration. A 230–fold purification and a final specific activity of 2.7U per mg protein was obtained. The enzyme has a M, of 93000 as estimated by gel filtration ans after SDS‐PAGE a single bannd with a M, of 50000 was found. Optima activity was found between pH 5 and pH 5.5.At low substrate concentrations equal amounts of fructose and glucose were produced (apperant Kw 55 mm). At higher sucrose concentrations progressively more isokestose was produced and fructose synthesis was inhibited. The high sucrose concentrations needed for isokestose systhesis do not support a physiological role for the enzyme in fructan biosynthesis.
Growth dynamics and associated mycorrhizal fungi of little bluestem grass [Schizachyrium scoparium (Michx.) Nash] on burned and unburned sand prairies
Authors: DHILHON SHIVCHARN S. , ANDERSON ROGER C. 
Published: September 2010

SUMMARYWP examined the influence of burning on little bluestem grass productivity and its vesicular‐arbuscular mycorrhizal (VAM) fungal associates in a sand prairie community over (bar growing seasons (1586‐4). Above‐and below‐ground productivity was higher on the burned sites than on the unhurried sites. Percent VAM funga1 colonization levels were significantly burned sites than on the unburned sites. In contrast, early in the growing season, colonized and specific rout lengths were longer on the burned site than on the unburned sites but differences were not always significant. Roots of plants on the burned sites supported more fungal biomass than roots on the unburned sites especially during the early growing season. However, colonization d:it;i suggest that the fungi were unable to keep up with the greater below‐ground production of plants on the burned prairies. Mycorrhizal inoculum potential levels of little bluestem rooi zone and randomly collected soil and VAM fungal spore densities were lower on the burned sites than the unburned sites during the year of the burn. Above‐ and below‐ground tissue samples showed significantly higher concentrations and accumulations of several inorganic, nutrients on the burned site early and later in the growing season.However, in contrast, plants on the unburned sites had greater nutrient‐use efficiencies for several nutrients than plants on the burned sites. Lower nutrient‐use efficiencies of plants on burned sites may in pan be due to the onset of harsher environmental conditions during the growing season and/or to associated VAM fungi‐ VAM fungi associated with plants on the burned sites are likely a carbon drain on these plants, supporting greater fungal biomass, and hence, plants on burned sand prairie sites may not benefit from their VAM fungal association especially early in the growing season.
Antifungal compounds from the roots of mycotrophic and non‐mycotrophic plant species
Authors: PAUL SCHREINER R. , KOIDE ROGER T. 
Published: September 2010

SUMMARYThe roots of twelve plant spades From bath mycotrophic (hosts of YAM fungi) and non‐mycotropic (non‐hosts) families were examined for their ability to produce antifungal compounds. A TLC bioassay was used with the fungus Cladosporium cucumerimun Ellis & Arch. Of the non‐mycotrophic species, five species from the Brassicaceae [Brassica kaber (DC.) Wheeler, Brassica napus L., Brassica campestris L.,Thlaspi arvense L., Rhaphanus raphasnistrum L.] had detectable antifungal compounds in extracts from roots, while two species from the Chenopodiaceae (Spinacea oleracea L., Beta vulgaris L.) and one species from the Amaranthaceae (Amaranthus retroflexus L.) did not. One mycotrophic species (Daucus carota L.) also had a detectable antifungal compound in root extracts, while three other mycotrophic species (Lactuca sativa LK., Abutilon theophrasti Medic., sorghum bicolor L.) did not. Chloroform extracts of B. kaber roots appeared to have the greatest quantity of extractable antifungal compounds as detarmined by the TLC bioassay. In a separate experiment, chloroform extracts from B. kaber roots greatly inhibited the germination of spores of Glomus etunicatum Becker and Gerd., while extracts from a number of other mycotrophic and non‐mycotrophic plant roots were only marginally inhibitory. Three antifungal compounds in chloroform extracts from B. kaber roots were shown to be derived from glucosinolates. The predominant antifungal compound was identified as +‐hydroxybenzyl isothiocyanate, the isothiocyanate produced by the action of myrosinase on glucosinalbin. The data provide evidence of a possible role for glucosinolates in determining the non‐mycotrophic status in B. kaber.
Factors affecting appressorium development in the vesicular–arbuscular mycorrhizal fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe
Authors: GIOVANNETTI MANUELA , AYIO LUCIANO , SBRANA CRISTIANA , SILVIA CITERNESI ANNA 
Published: September 2010

SUMMARYInvestigations on the luck of appressorium formation in the roots of the non‐host plant Lupinus albus L. showed that root exudates do not inhibit mycelial growth of the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, but that they hinder hyphal attachment and fungal recognition of roots. Exudates do not stimulate hyphal proliferation in the rhizosphere. G. mosseae hyphae were able to recognize and attach to excised root of both lupin and host plants, forming swellings resembling apressoria. No growth of G. mosseae hyphae was observed around simulated roots consisting of nylon, silk, polyamide and glass threads, whereas appressoria were formed on heterologous hyphae of VAM fungal species. The hypothesis that a purely thigmotropic stimulate could trigger hyphal attachment and the further differentiation of appressoria was excluded.
Photosynthetic activity of Scots pine (Pinus sylvestris L.) needles during winter is affected by exposure to SO2 and NO2 during summer
Authors: STRAND MARTIN 
Published: September 2010

SUMMARYA 50‐year‐old stand of Scots pine (Pinus sylvestris L. with a mean height of 12 m. located 60 km northwest of Umeå in northern Sweden, was furnigated with SO2 and NO2 from June to September in 1998 and 1989. SO2 and NO2 were released from vertical vent‐pipes arranged ina circle with a diameter of 60m. During fumigation, the average concentrations of both SO2 and NO2 in the centre of the circle were 10–15 nl l‐1. Measurements of CO2 evolution and chlorophyll a fluorescence of needles were made under laboratory conditions. For samples collected in January of 1989 and 1990, the light‐ and CO2‐saturated rate of O2 evolution at 20°C in needles of trees exposed to SO2+ NO2 was lower than in needles of trees exposed to ambient clean air. Furthermore, the photochemical efficiency of photosystem II, as indicated by the ratio of variable to maximum fluorescence was lower for needles of fumigated trees, in samples collected in December 1989 and January 1990. These results suggest that low concentrations of SO2+ NO2 may have significant long‐term effects n the photosynthetic apparatus in needles of Scots pine. The observed responses may be triggered by unfavourable environmental conditions during autumn and winter. However, no evidence for a greater sensitivity to prolonged freezing stress at –19°C was found in needles of trees exposed to SO2+ NO2 when measured in December or January.
Response of radish to multiple stresses
Authors: PELL E. J. , SINN J. P. , ECKARDT R , VINTEN JOHANSEN C. , WINNER W. E. , MOONEY H. A. 
Published: September 2010

SUMMARYExperiments were conducted 10 determine what impact ozone (O3) and/or soil moisture deficit had on tile growth and development of radish plums. Plants of Raphanus sativus L. Cherry Belle and Raphanus sativus × raphanistrum (wild type) grown in modified open‐top chambers, were treated with O3 and/or subjected to reduced soil moisture throughout growth and development. Experiments were performed in the spring and autumn of 1989. Plants nr both genotypes exhibited a more adverse response to soil moisture deficit in the spring experiment and in O3, in the autumn experiment. The higher light intensity and temperature prevailing in the spring, in contrast to those during the autumn, were thought to favour a negative impact of reduced soil moisture. The spring conditions fostered high relative growth rate and more rapid water loss by the shoot on both a relative and absolute basis. These same conditions may have placed the plants in a physiological state which minimized toxicity by O3. Carbon partitioning in the spring favoured reproduction while the autumn carbon was preferentially partitioned to the hypocotyl and foliage for Cherry Belle and Wild Type, respectively. The importance of these partitioning differences between genotype was explored as it related to injurious and compensatory responses to the two Stresses. Since the plants were not equally sensitive to reduced soil moisture and O3, in the same experiments, interactions were frequently absent. When interactions occurred, O3 injury was reduced in plants also grown in soil with reduced moisture content.
Pollination‐dependent female reproductive success in a self‐compatible outcrosser, Asphodelus aestivus Brot.
Authors: SCHUSTER AYELET , NOY‐MEIR IMANUEL , HEYN C. CLARA , DAFNI AMOTS 
Published: September 2010

SUMMARYExperiments were carried out, during three years (1986‐8), on a population of Asphodelus aestivus Brot. (Liliaceae) in n semi‐arid environment, to test whether seed production of plants was limited by quantity and/or quality of pollen supply. The natural pollinator are mainly solitary bees.The fraction pf flower setting MM varied from 8 to 40% between years. Fruit set of plants caged to exclude inserts was less than 3%. Fruit set was increased by artificial pollination of flowers with their own pollen to 43‐64%, This indicates that the plant is self‐compatible, but due to the position of the anthers and stigma, insect visits are required for effective pollination. Cross‐pollinated caged flowers set yet more fruits (59–82%) and much more (2‐4 times) full seeds per fruit than self‐pollinated flowers.The artificial addition of cross‐pollen to flowers, in the natural environment, increased the moan number of full seeds per flower on the whole plant. Thus, natural reproduction was limited by insect pollination.A quantitative Biffed was indicated by a strong positive association between the number of pollen grains on a stigma and the probabilities of the flower maturing a fruit and of its ovules setting seeds. Furthermore, in 20‐60% of [lowers in the population, stigma loads were less than 13 pollen grains, which indicated very low probability of fruit maturation.A qualitative response was shown by the positive effect of artificially added cross‐pollen on the number of full vs. empty seeds, an effect similar to that of cross‐ vs. self‐pollination in caged plants.The proportion of full seeds developing in a clone of Asphodelus in the natural population was inversely related to the proportion of inflorescences in its neighbourhood that belonged to the same clone, which suggests that fertility is limited by an excess of pollen from the same clone being supplied by insects.It is concluded that female reproductive success of Asphodelus aestivus in its natural environment depended on both the amount and origin of the pollen supplied by us pollinators.
Variation within white clover (Trifolium repens L.) for phenotypic plasticity of morphological and yield related characters, induced by phosphorus supply
Authors: CARADUS J. R. , HAY M. J. M. , MACKAY A. D. , THOMAS V. J. , DUNLOP J. , LAMBERT M. G. , HART A. L. , VAN DEN BOSCH J. , WEWALA S. 
Published: September 2010

SUMMARYThe range of variation for phenotypic plasticity for morphological and yield related characters caused by varying the level of phosphorus (P) supply, was determined both across and within cultivars of white clover [Trifolium repens L.). Analysis of variance was used as a quolitative measure of phenotypic plasticity (i.e. significance of P effect) and to determine differential phenotypic plasticity (i.e. significance of genotype × P interaction). Quadratic P response curves were calculated and plasticity measured quantitively as maximum slope.While all plant characters measured exhibited plasticity, yield related characters were generally more plastic titan characters associated with plant morphology when compared using a scale independent test based on F‐ratios. Internode length and leaf size were the must plastic morphological characters and it is suggested that they are chiefly responsible for the resultant yield response of white clover to increased phosphate fertiliser supply. There was highly significance of variation for plasticity among genotypes for all plant characters measured, although within cultivars, significance of variation for plasticity among genotypes varied with cultivar. Magnitude of plasticity of genotype was not closely related to origin of cultivar. plant type, growth or breeding history. Many characteristics varied independently for an increase or decrease in plasticity of characters is an achievable option.