bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fructan metabolism in leaves of Lolium rigidum Gaudin
Authors: SMOUTER HENK , SIMPSON RICHARD J. 
Published: April 2006

summaryAccumulation of water‐soluble carbohydrates (WSC) in leaves of intact seedlings of annual ryegrass (Lolium rigidum Gaudin cv. Wimmera) was studied using a novel model system. The roots and leaf bases of intact seedlings, grown in nutrient solution, were cooled to 5°C to reduce sink activity and the production of photosynthates was enhanced by continuous illumination of the plants. This resulted in accumulation of WSC in the shoots. Thin‐layer chromatography showed the presence of a complex series of fructans, distinct from those found in tubers of Helianthus tuberosus. Two trisaccharides, 1‐kestose and neokestose, were present in various proportions, but no 6‐kestose was detected in the shoots. After feeding 14CO2 to the seedlings in a pulse‐chase experiment, high specific radioactivity was measured in monosaccharides, sucrose and fructan oligosaccharide fractions to DP 5 within 1 hr. These fructan pools were rapidly turned over without significant accumulation of fructans during the first 16 h of the accumulation phase. Neokestose and 1‐kestose contained equally high specific radioactivity, 1 h after feeding. These results indicated that neokestose was possibly as important as 1‐kestose as a possible precursor for synthesis of fructan. Concentrations of WSC increased linearly from 2 to 14 mg g−1 f. Wt of the leaves after 16 h and reached a concentration of 30 mg g−1 f. wt after 64 h. Sucrose, glucose and fructose were the first sugars to be accumulated and reached concentrations of 10, 3.5 and 2.5 mg g−1 f. wt, respectively. Tri‐ and tetrasaccharide accumulated to measurable concentrations after approximately 16 h of treatment and reached concentrations of 2.5 and 2.0 mg g−1 f. wt, respectively. The appearance of these oligosaccharides occurred when sucrose and monosaccharides reached stable concentrations in the leaves, The WSC concentration declined at a rate of about 0.8 mg g−1 f. wt h−1, when the root temperature was raised to 24°C after 64 h and plants were darkened. The decline in WSC concentration was accompanied by a 70% decline in sucrose concentration and a decline in all other fructan concentrations, white the concentration of fructose increased 2‐fold.
Carbohydrates on the surface of urediniospore‐ and basidiospore‐derived infection structures of heteroecious and autoecious rust fungi
Authors: FREYTAG S. , MENDGEN K. 
Published: April 2006

summaryNine flucirescein isothiocyanate‐labelled lectins with affinity towards different carbohydrates were used to probe the surface carbohydrates of infection structures in vitro, derived from urediniospores and basidiospores of an autoecious rust species, Uromyces viciae‐fabae (Pers. J Schroet., and of a heteroecious rust species, Uromyces rumicis (Schum.) Wint. Lectin binding was quantified by measuring fluorescence photometrically.All lectins bound in a characteristic pattern to the infection structures of the respective spore types of each rust fungus. Differences were especially obvious between those infection structures normally produced inside leaf tissue, namely the urediniospore‐derived substomatal vesicles with infection hyphae, and the basidiospore‐derived intraepidermal vesicles. The dikaryotic stage and the monokaryotic stage of the heteroecious fungus differed mainly in their affinity for the leotins from Bandeira simplicifolin and Lotus tetragonulobus.A statistical analysis comparing the binding of the lectins to infection structures of Two rust fungi suggested that cell surface composition is determined by nuclear condition. The monokaryotic stages of both rust fungi have a higher degree of similarity than the dikaryotic and monokaryotic stages of the same rust fungus.
Effect of root‐zone salinity on growth and chemical composition of Acacia ampliceps B. R. Maslin, A. auriculiformis A. Cunn. ex Benth. and A. mangium Willd at two nitrogen levels
Authors: MARCAR NICO E. , DART PETER , SWEENEY COLLEEN 
Published: April 2006

summary Acacia ampliceps B. R. Maslin, A. auriculiformis A. Cunn. ex Benth. and A. mangium Willd. differ in their salt tolerance. Four‐month‐old seedlings were treated with 100 (S1), 200 (S2) and 400 (S3) mol m−3 NaCl in sand culture. Two months prior to NaCl application the seedlings had been pretreated with either 1 mol m−3 N (low N: LN) or 5 mol m−3 N (high N:HN) as ammonium nitrate. LN seedlings were inoculated with a suspension of Rhizobium.HN plants were considerably larger than inoculated plants at each NaCl concentration. Survival, damage symptoms and relative growth reduction under NaCl were generally similar for both N treatments. There was also no effect of N level on shoot water relations and stomatal conductance of youngest expanded phyllodes. However, at S1 and S2, HN plants had significantly lower concentrations of shoot Na+ and Cl− concentrations than LN plants.There were differences in nodule number and weight per plant between species receiving the LN treatment. Nodule dry weight and nitrogenase (acetylene reduction) activity was more sensitive than plant dry weight to NaCl imposition.Ranking of species for salt tolerance, based on relative decline in dry weight of shoot, whole plant and nodules under NaCl addition, was in the order A. ampliceps > A. aurtculiformsis > A. mangium. The greater salt tolerance of A. ampliceps was associated with relatively low shoot Na+ and Cl− concentrations (dry weight basis) and high phyllode succulence.
Terrestrial rhizophytes and H+ currents circulating over at least a millimetre: an obligate relationship?
Authors: RAVEN JOHN A. 
Published: April 2006

summaryCirculating ionic currents are apparently ubiquitous in growing and differentiating eukaryotes. In many the current is carried by H+, in which case the medium around the apex of growing organs is alkalinized while the medium adjacent to subapical portions is acidified. These two zones may help in, respectively, molybdenum acquisition and reduction of aluminium toxicity, and phosphorus and iron acquisition, by rhizophytic plants. An analysis of the taxonomic distribution of H+‐borne circulating current shows that all rhizophytes (terrestrial, freshwater and, probably, marine) except those in the green algal class Ulvophyceae have such currents; the Ulvophyceae have circulating currents carried by Cl−. The Ulvophyceae do not seem to have any alternative means of causing pH zonation in the rhizosphere. Their marine habitat, with the possibility of molybdenum acquisition from the alkaline bulk water phase, may mean that the Ulvophyceae are not disadvantaged by the absence of rhizosphere acid‐alkaline zonation as would be a land plant; similarly, they are less likely to suffer aluminium toxicity to the growing zone of rhizoids. Ulvophyceae do not occur as terrestrial plants; this may relate not only to the absence of rhizosphere pH zonation in these organisms but also to mechanical problems related to their coenocytic habit, which in turn results from their inability to produce plasmodesmata.
Towards an understanding of the differences between the blepharoplasts of mosses and liverworts, and comparisons with hornworts, biflagellate lycopods and charophytes: a numerical analysis
Authors: RENZAGLIA KAREN S. , DUCKETT JEFFREY G. 
Published: April 2006

summaryNumerical analysis of the lengths and positions of the two basal bodies (BBs), lamellar strip (LS) and anterior mitochondrion (AM) relative to each other in mid‐ and late‐stage spermatids of mosses and liverworts reveals the existence of several well denned, but previously unrecognized, features which clearly distinguish the blepharoplasts of the two groups. The ten possible quotients were calculated from measurements of anterior BB lengths, posterior BB lengths, LS lengths, distances between the anterior tips of the BBs and distances between the transition regions of the BBs in mid‐stage spermatids of 9 mosses and 16 hepatics. These critical data may be quickly compiled from a small number of electron micrographs. A Mann‐Whitney rank order t test showed highly significant differences in 6 of the 10 quotients between the moss and liverwort taxa. The primary data for late‐stage spermatids (4 mosses, 6 liverworts) also included the length of the AM. A Wilcoxon signed rank procedure revealed that the relationship between the AM and other blepharoplast components changed significantly between mid‐ and late‐stage spermatids in mosses but not in liverworts. The clear‐cut numerical differences between the blepharoplast components in each group are related to different patterns of development namely (1) bidirectional assembly of the LS in young spermatids of liverworts versus unidirectional (anterior) elongation at the same stage in mosses (2) elongation of the posterior BB over the nucleus in mid‐stage spermatids of mosses and (3) maturational elongation of the AM in mosses. Since the differences between the blepharoplasts of mosses and liverworts become apparent only during the later stages in ontogeny and since the mode of development of basal body stagger, involving the same precisely defined patterns of proximal triplet microtubule extension, is unique to mosses and liverworts, we suggest that the two groups share a common ancestry.The blepharoplasts of all the taxa used in the calculations are illustrated in a simplified form and the ‘average’ blepharoplast for mid‐ and late‐stage spermatids of both mosses and liverworts is reconstructed from all the data presently available on the two groups. The same analysis of the blepharoplasts of hornworts, birlagellate lycopods, and charophytes highlights the differences between these groups and mosses and liverworts. Most striking is the side‐by‐side orientation of the basal bodies in hornworts and charophytes compared with the staggered arrangement in mosses, liverworts and the lycopods.
Continuity of chloroplast and endoplasmic reticulum membranes in Phaseolus vulgaris
Authors: WHATLEY J. M. , McLEAN B. , JUNIPER B. E. 
Published: April 2006

summaryIn cells of young primary leaves of Phaseolus vulgaris, the ER briefly, but regularly, forms a partial sheath around the plastids or lies in dose proximity to them. We have shown previously that, when ER encircles the chloroplasts in the lower vascular plant Equisetum telmateia, the ER membrane can become continuous with the outer membrane of the plastid envelope. It is now apparent that similar membrane continuity can become established between the ER and plastids in the angiosperm, Phaseolus vulgaris, though the period of organelle association is of much shorter duration than in Equisetum and it is characteristic only of the earlier stages of amyloplast development. A comparison is made of the relative timings of association of ER with protein bodies and mitochondria as well as with plastids.
Development and structure of resin glands on tissues of Betula pendula Roth, during growth
Authors: LAPINJOKI SEPPO P. , ELO HEIKKI A. , TAIPALE HANNU T. 
Published: April 2006

summary Betula pendula Roth, and a number of other species of the genus are known to excrete resinous chemicals on juvenile shoots and twigs as deterrents against herbivores. The present studies show that the resin is produced by specific multi cellular glands that are of the same ontogenetic origin as the glands covering developing tissues in buds during winter dormancy. It was possible to deduce from observations over a season that the resin production may be regulated at two levels. Density of the glands on the shoot surface is determined at the time of tissue differentiation in the beginning of primary growth, and the excretory activity is related at least in part to gland size. Towards the end of the growth period the cores of glands were gradually filled with bark cells and the interior of the columnar excretory cells of their epidermis appeared pale and hollow instead of the dense blue in younger glands, when stained with haematoxylin. The excretion of resin by B. pendula appears to be a primary defence mechanism that is active during that part of the season, when apical growth of a juvenile shoot takes place.
Nitrogen transfer from nodulating soybean [Glycine max (L.) Merr.], to corn (Zea mays L.) and non‐nodulating soybean in intercrops: direct 15N labelling methods
Authors: MARTIN R. C. , VOLDENG H. D. , SMITH D. L. 
Published: April 2006

summaryIn order to test for N transfer to com (Zea mays L.) or to non‐nodulating soybean [Glycine max [L.] Merr.), nitrogen enriched in 15N was directly applied to a petiole or to secondary roots of adjacent nodulating soybean. In the field in 1988, 15N applied directly to a petiole of nodulating soybean was detected at significantly higher levels in adjacent corn plants than when un enriched N was similarly applied. Applications of enriched N and un enriched N to nodulating soybean roots did not result in significant differences in %15N an adjacent corn plants. However, in greenhouse experiments, enriched N applied in split‐root systems to secondary roots of nodulating soybean, was detected at higher levels in associated corn and non‐nodulating soybean than when un enriched N was similarly applied.
Starch synthesis in developing pea embryos
Authors: SMITH ALISON M. , DENYER KAY 
Published: April 2006

summaryThe pea embryo stores about half of its carbon as starch and has proved to be an excellent system on which to study the nature and regulation of the pathway of starch synthesis. The developing embryo receives its carbon as sucrose, which is metabolized via glycolysis in the cytosol of cotyledonary cells. Glucose 6‐phosphate enters the amyloplast – probably via a phosphate‐exchange translocator – where it is converted to ADPglucose via phosphoglucomutase and ADPglucose pyrophosphorylase. ADPglucose pyrophosphorylase is the site of action of a mutation at therblocus, which reduces activity by more than 90 % and the rate of starch synthesis by about 50 %. Study of mutant and wildtype embryos reveals that one of four putative subunits of the enzyme is eliminated by the mutation. Three distinct isoforms of starch synthase catalyze the incorporation of the glucosyl moiety of ADPglucose into starch. Two of these are probably active in the soluble phase of the amyloplast and become incorporated into the granule as it grows, while the third is almost exclusively granule‐bound. Analysis of cDNA clones for starch synthases shows that the exclusively granule‐bound form is very similar to the ‘waxy’ gene product believed to be responsible for amylose synthesis in cereal endosperms. The soluble starch synthases show some similarities to the ‘waxy’ proteins, but clearly belong to a different and previously undescribed class of starch synthases. The pea embryo contains two forms of starch branching enzyme, which are encoded by different genes, are maximally expressed at different times in development, and have different kinetic properties. It is likely that they play different roles in the synthesis of the granule. A mutation at therlocus, which reduces the rate of starch synthesis by about 50% and increases the amylose content of the starch from 30% to 70%, consists of a transposon‐like insertion in the gene encoding starch‐branching enzyme I. Activity of this isoform is abolished by the mutation.CONTENTSSummary21I.Introduction21II.The supply of sucrose to the embryo22III.The timing and location of starch synthesis23IV.The supply of carbon to the amyloplast23V.Mutations affecting the committed pathway of starch synthesis26VI.The committed pathway28Acknowledgements31References31
Cytokinins in the xylem sap of desert‐grown almond (Prunus dulcis†) trees: Daily courses and their possible interactions with abscisic acid and leaf conductance
Authors: Fußeder A. , Wartinger A. , Hartung W. , Schulze E.‐D. , Heilmeier H. 
Published: April 2006

summaryXylem sap samples were obtained from one‐ to four‐year‐old almond trees [Prunus dulcis (Miller) D. A. Webb] that had been grown in lysimeters of different volumes with different amounts of available water and subjected to an annual drying cycle. The samples were analyzed for cytokinin patterns by ELISA during the growing season. Free bases, ribosides and nucleotides of the N6‐(Δ2‐isopentenyl) adenine (iP) and the zeatin (Z) type could be identified and quantified. Z‐type cytokinins were always predominant. In many cases the concentrations of the cytokinin fractions were rather constant during the day. In a limited number of days, however, Z‐type cytokinins showed peak concentrations in the morning and a rapid decrease in the afternoon. A correlation between water status of the trees and the concentrations of cytokinins or their daily variations in the xylem sap could not be established. When the concentration of abscisic acid in the xylem sap was not limiting leaf conductance, daily‐variation of a cytokinin fraction preceded daily variation in leaf conductance. We conclude that in almond trees, cytokinins may affect stomatal behaviour on a short‐term basis. This is an outcome of changes in their xylem sap concentrations during the course of a day. Abscisic acid, on the other hand, acts as an opposing signal, the size of which reflects long‐term water deficit.
Effects of ozone and acidic fog on red spruce needle epicuticular wax production, chemical composition, cuticular membrane ultrastructure and needle wettability
Authors: PERCY K. E. , JENSEN K. F. , McQUATTIE C. J. 
Published: April 2006

summaryOne‐year‐old red spruce (Picea rubens Sarg.) seedlings were exposed, from bud break, to ozone (O3) and acidic fog for 14, 42 or 77 days. Ozone was more damaging than acidic fog to epicuticular wax. Wax quantity on needles exposed to charcoal‐filtered air (CFA) and pH 4.2 fog (control) increased from 14 to 42 days, but decreased by 77 days. Exposure of elongating needles to 70 ppb O3 and pH 4.2 fog reduced the rate of de novo wax synthesis. Red spruce wax is composed of secondary alcohols (50%), nonacosane diols (25%), alkyl esters (12%), primary alcohols (6 %), estolides (2 %), fatty acids (3 %), and hydroxy‐fatty acids (2 %). Wax chemical composition varied temporally. Needles exposed to O3 had significantly less secondary alcohols, diols, alkyl esters, fatty acids, and hydroxy‐fatty acids than needles exposed to CFA. Production of secondary alcohols was significantly reduced following needle exposure to fog at pH 3.0. Cuticular membrane thickness increased significantly following needle exposure to O3. The increase in thickness at 250 ppb O3 was due to a new amorphous layer which appeared above the reticulate layer. Contact angles on needles exposed to CFA and pH 4.2 fog increased from 92° after 14 days to 96° after 42 days, then declined to 77° after 77 days. Needle exposure to O3 for 42 or 77 days significantly decreased contact angles.
Effects of long‐term ozone exposure and drought on the photosynthetic capacity of ponderosa pine (Pinus ponderosaLaws.)
Authors: BEYERS JAN L. , RIECHERS GEORGE H. , TEMPLE PATRICK J. 
Published: April 2006

summarySeedlings of ponderosa pine (Pinus ponderosaLaws.) were grown for three years under three atmospheric ozone concentrations – clean air (CF), ambient ozone (NF), and 15 times ambient ozone (NF150)–at a moderately‐polluted site in the Sierra Nevada, under either well‐watered or drought‐stressed conditions. When the trees were 5 years old, photosynthetic capacities of 2‐year‐old, 1‐year‐old, and current‐year needles were measured during August and September of the 3rd season of exposure. Current‐year needles of NF150 trees had higher photosynthetic capacity than NF and CF trees during late summer, an effect due to greatly enhanced photosynthesis in well‐watered plants that had lost older needles as a result of ozone damage. This photosynthetic compensation in well‐watered NF150 seedlings was related to higher tissue nitrogen concentration in the current‐year foliage and possibly to increased inorganic phosphate cycling, both responses to the loss of older needles. Drought‐stressed NF150 seedlings were partially protected from ozone damage by decreased stomatal conductance and did not exhibit the same degree of photosynthetic compensation. No differences in photosynthetic rate were found between CF and NF seedlings or between well‐watered and drought‐stressed seedlings (across ozone treatments) in any needle age class.
Effects of dry‐deposited sulphur dioxide on fungal decomposition of angiosperm tree leaf litter III. Decomposition rates and fungal respiration
Authors: NEWSHAM K. K. , BODDY LYNNE , FRANKLAND JULIET C. , INESON P. 
Published: April 2006

summaryAsh (Fraxinus excelsiorL.), birch (Betulaspp.), hazel (Corylus avellanaL.), sessile oak [Quercus petraea(Mattuschka) Liebl.] and sycamore (Acer pseudoplatanusL.) leaf litters from a virtually non‐polluted and a heavily sulphur dioxide (SO2)‐polluted woodland were fumigated with environmentally‐realistic concentrations (0.010–0.030μl l−1) of SO2for 16–68 wk in an open‐air field‐fumigation experiment. Fumigation inhibited the respiration (CO2evolution) and decomposition rates of the leaf litters. However, there were few differences in the responses between leaf litters from the two woodlands.In addition, pure cultures of four saprotrophic fungi were grown individually on irradiated hazel litter and exposed toc.0.030μl l−1of gaseous SO2, for 28 d in the laboratory. The gas inhibited the respiration ofPhoma exiguaDesm. andPhoma macrostomaMont, but not the respiration ofCladosporium cladosporioides(Fres.) de Vries orConiothyrium quercinumSacc. var.glandicolaGrove. These results in part substantiated findings of previous experiments examining the effects of SO2on the structures of saprotrophic fungal communities. The effects of SO2on fungal decomposition of angiosperm tree leaf litter as possible causes of forest decline are discussed.
Distribution of VA mycorrhizal entry points near the root apex: Is there an uninfectible zone at the root tip of leek or clover?
Authors: SMITH S. E. , DICKSON S. , WALKER N. A. 
Published: April 2006

summaryThis paper re‐examines the question of the susceptibility of plant roots to infection by vesicular‐arbuscular mycorrhizal fungi, particularly near the root apex. The cumulative distributions of the observed distance between the root apex and the most apical mycorrhizal entry points are compared with expected distributions based on (i) a random distribution of successful encounters between hypha and root and (ii) an uninfectible apical region (of length Zo). Data for both Allium porrum L. (leek) and Trifolium subterraneum L. (clover) are well fitted by the expected distributions and in the majority of cases (17/31) the best fit is obtained with zero Zo, with 8 additional cases being best fitted by values of Zo of 1 mm or less. Even where the best fits are obtained with values of Zo greater than zero, the distribution using Zo= 0 is still within the confidence limits for the data. These findings indicate that in neither species is there clear evidence for a subapical region that is immune to infection. The fact that there are short uninfected lengths immediately behind the apex is interpreted as representing a delay between an encounter and a detectable infection. Other consistent deviations of the data from the theoretical distributions are discussed.Fitting the distributions yields values for the frequency of infection (A). These are compared for the two host plants at different propagule densities. The values for leek are much lower than for clover. In both species there are increases in A with increases in propagule density which are consistent with earlier findings.