bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relative growth rate correlates negatively with pathogen resistance in radish: the role of plant chemistry
Authors: HOFFLAND E. , NIEMANN G. J. , VAN PELT J. A. , PUREVEEN J. B. M. , EIJKEL G. B. , BOON J. J. , LAMBERS H. 
Published: April 2006

ABSTRACTPlant growth rate has frequently been associated with herbivore defence: a large investment in quantitative defence compounds occurs at the expense of growth. We tested whether such a relationship also holds for growth rate and pathogen resistance. For 15 radish (Raphanus sativus L.) cultivars, we determined the potential growth rate and the resistance to fungal wilt disease caused by Fusarium oxysporum. We subsequently aimed to explain a putative negative relationship between growth rate and resistance based on plant chemical composition. Both growth rate and resistance level varied greatly among cultivars. Moreover, there was a strong negative correlation between growth rate and resistance, i.e. there are costs associated with a high resistance level. Roots of slow‐growing, resistant cultivars have a higher biomass density. Using pyrolysis mass spectrometry. we part1y explained variation in both growth rate and resistance in terms of the same change in chemical composition. Leaves of slow‐growing, resistant cultivars contained more cell wall material. Surprisingly, roots of slow‐growing, highly resistant cultivars contained significantly less cell wall material, and more cytoplasmic elements (proteins). We speculate that this higher protein concentration is related to high construction and turn‐over costs and high metabolic activity. The latter in turn is thought to be responsible for a rapid and adequate resistance reaction, in which phenols may be involved.
The relationship between the relative growth rate and nitrogen economy of alpine and lowland Poa species
Authors: ATKIN O. K. , BOTMAN B. , LAMBERS H. 
Published: April 2006

ABSTRACTThis study investigates the nitrogen economy of six altitudinally contrasting Poa species which differ in their relative growth rate (R). Two alpine (Poa fawcettiae and P. costiniana), one sub‐alpine (P. alpina)and three temperate lowland species (P. pratensis, P. campressa and P. trivialis) were grown hydroponically under identical conditions in a growth room. The low R exhibited by the alpine species was associated with lower plant organic nitrogen concentration (np) and lower nitrogen productivity (Πp, amount of biomass accumulation per mol organic nitrogen and time). The differences in Πp between the alpine and lowland species did not appear to be due to differences in the carbon concentration or the proportion of total plant organic nitrogen allocated to the leaves, stems or roots. Variations in ΠP were also not due to variations in photosynthetic nitrogen use efficiency (ΨN, the rate of photosynthesis per unit organic leaf nitrogen) or shoot or root respiration rates per unit organic nitrogen (ΛSH and ΛR, respectively) per se. Rather, the lower Λp in the alpine species was probably due to a combination of small variations in several of the parameters (e.g. slightly lower ΨN, slightly higher ΛSH and ΛR, and slightly higher proportions of total plant organic nitrogen allocated to the roots). The alpine species exhibited lower organic acid and mineral concentrations. However, no differences in whole‐plant construction costs (grams of glucose needed to synthesize one gram of biomass) were observed between She alpine and lowland Poa species. The lack of sub‐stantial differences in ΨN between the alpine and lowland species contrasts with the large differences in ΨN between slow‐ and fast‐growing lowland species that have been reported in the literature. The reasons for the unusually high ΨN values exhibited by the alpine Poa species are discussed.
Cell wall composition of leaves of an inherently fast‐ and an inherently slow‐growing grass species
Authors: GROENEVELD H. W. , BERGKOTTE M. 
Published: April 2006

ABSTRACTDifferences in the relative growth rules of the inherently slow‐growing Deschampsia flexuosa L. and the inherently fast‐growing Holcus lanatus L. were reflected in cell wall synthesis in the elongation zone of the leaves. Leaf elongation rates depended on the size of the plant and ranged from 6 to 14 mm d−1 in Deschampsia and from 12 to 42 mm d−1 in Holcus. Anatomical data showed that the epidermis and vascular tissue are the important tissues controlling leaf extension. The cell wall polysaccharides of fully expanded leaves of the two species were identical in sugar composition. Enzymatic hydrolysis of polymeric sugars in the cell walls of the sheath and the lamina gave glucose (85%), arabinose (3.5%), fucose (0.5%), xylose (5.0%), mannose (0.5%), galaclose (0.8%) and galacturonic acid (3–4%). This composition applied throughout the blade and the sheath and did not change with ageing. Polysaccharides in the meristems of the two species showed identical sugar compositions with 51–55% glucose, 13–15% galactoronic acid and 13–14% arabinose as the main components. The extension zone was marked by a gradual increase of driselase‐digestable polymers (per mm tissue) and a concurrent shift in sugar composition. The massive increase of glucose in the cell wall polymers of the elongation zone is probably caused by cellulose synthesis. The rate of synthesis of cell wall polysaccharides in Holcus was twice as high as that in Deschampsia. The slower‐growing Deschampsia has more ferulic acid esterified with cell walls, which might contribute to the slowing of leaf growth. Lignin is not significantly deposited until growth has essentially ceased and is not responsible for the difference in growth rate.
Location of sugars in barley seeds during germination by NMR microscopy
Authors: ISHIDA N. , KOIZUMI M. , KANO H. 
Published: April 2006

ABSTRACTThe distribution and fluctuation of sugars in germinating barley seeds were examined by13C nuclear magnetic resonance (NMR) spectroscopy,1H‐NMR imaging and1H‐NMR localized spectroscopy in relation to morphology. Maltose, sucrose, fructose and oils were detected in intact imbibed seeds by13C‐NMR spectra. During the first 6 d of germination, the maltose content increased and the oil content gradually decreased, whilst the levels of sucrose and fructose remained constant. Sugars were located by1H‐NMR images and1H‐NMR localized spectra in the vascular bundle of the seeds as well as in the solubilized endosperm. They were also detected in the shoots. The sugars detected in an 80% ethanol shoot extract were sucrose and glucose, which were located in the vascular bundles but not in the mesophyll cells of the coleoptile. They were also located in the basal part of the shoot, but not above 7 mm from the scutellum. The data suggest that the sugars are primarily transported through the vascular bundles and, at the same time, rapidly incorporated into mesophyll cells in the leaves.
Molecular phylogeny of Flaveria as deduced from the analysis of nucleotide sequences encoding the H‐protein of the glycine cleavage system
Authors: KOPRIVA S. , CHU C.‐C. , BAUWE H. 
Published: April 2006

ABSTRACTSequence comparisons have shown that nucleotide sequences of the H‐protein, a component of the glycine cleavage system, are only moderately conserved and can be used as molecular markers for intrageneric phylogenetic studies. We have analysed the respective cDNA sequences from 12 species of Flaveria, and a more limited set of gdcsH upstream regions. These data are discussed with respect to a phylogenetic reconstruction of Flaveria, a small genus which includes species of different photo‐synthetic types, namely C3, C3‐C4, C4‐like and C4. Our analysis essentially supports an earlier hypothesis, based on morphological and eco‐geographical data, of the evolution of Flaveria (Powell 1978). This close agreement shows the usefulness of H‐protein nucleotide sequences at a low taxonomic level. Our analysis independently confirms that C4 photosynthesis has evolved two times in different lineages of Flaveria. Most remarkably, the C4 taxa of Flaveria appear as derived relative to the C3‐C4 intermediate taxa, i.e. they probably have common direct predecessors. This is the first direct evidence for a phylo‐genetically intermediate position of C3‐C4 intermediate photosynthesis. Our data also confirm the antiquity of C3 photosynthesis in Flaveria but suggest that the collection of F.pringlei used in our experiments, although clearly of C3 photosynthetic metabolism, possibly originated from hybridization with a more advanced taxon.
Interactions between K+ and NH4+: effects on ion uptake by rice roots
Authors: WANG M. Y. , SIDDIQI M.Y. , GLASS A. D. M. 
Published: April 2006

ABSTRACTInteractive effects of K+ and N (principally NH4+) on plant growth and ion uptake were investigated using hydroponically grown rice (Oryza sativa L. cv. M202) seedlings by varying the availability of NH4+ or NO3− and K+ during an 18d growth period, a 3d pretreatment period and during flux measurements. Plants grew best in media containing 100 mmol m−3 NH4+ and 200mmolm−3 K+ (N100/K200), followed by N2/K200 < N100/K2 < N2/K2. 86Rb+(K+) fluxes were increased by exposure to N during the 18 d growth period and the 3 d of pretreatment, but decreased by the presence of NH4+ during flux measurements. This inhibition was a function of prior N/K provision and the [NH4+]0 present during flux determinations. NH4+ was least inhibitory to 86Rb+(K+) influx in high‐N/low‐K plants. Pretreatments with K+ failed to stimulate NH4+ uptake, and the presence of K+ in the uptake solutions reduced NH4+ fluxes only in high‐N/low‐K plants.
Thermodynamic analysis of the physical state of water during freezing in plant tissue, based on the temperature dependence of proton spin‐spin relaxation
Authors: MILLARD M. M. , VEISZ O. B. , KRIZEK D. T. , LINE M. 
Published: April 2006

ABSTRACTMulti‐proton spin‐echo images were collected from cold‐acclimated winter wheat crowns (Triticum aestivumL.) cv. Cappelle Desprez at 400 MHz between 4 and −4 °C. Water proton relaxation by the spin‐spin (T2) mechanism from individual voxels in image slices was found to be mono‐exponential. The temperature dependence of these relaxation rates was found to obey Arrhenius or absolute rate theory expressions relating temperature, activation energies and relaxation rates, Images whose contrast is proportional to the Arrhenius activation energy (Ea), Gibb's free energy of activation (ΔG‡), and the entropy of activation (ΔS‡) for water relaxation on a voxel basis were constructed by post‐image processing. These new images exhibit contrast based on activation energies rather than rules of proton relaxation. The temperature dependence of water protonT2relaxation rates permits prediction of changes in the physical state of water in this tissue over modest temperature ranges. A simple model is proposed to predict the freezing temperature kof various tissue in wheat crowns. The averageEaand ΔH‡for water protonT2relaxation over the above temperature range in winter wheat tissue were −6.4 ± 14.8 and −8.6 ± 14.8kj mol−1, respectively. This barrier is considerably lower than theEafor proton translation in ice at 0°C, which is reported to be between 46.0 and 56.5 kj mol−1
Phloem‐specific expression of pyrophosphatase inhibits long distance transport of carbohydrates and amino acids in tobacco plants
Authors: GEIGENBERGER P. , LERCHI J. , STITT M. , SONNEWALD U. 
Published: April 2006

ABSTRACTAs reported in a previous paper [Lerchl et al. (1995) Plant Cell, 7, 259–270], expression of Escherichia coli inorganic pyrophosphatase in the cytosol under the control of the phloem‐specific rolC promoter from, Agobacterium rhizogenes results in decreased growth of transgenic tobacco plants. In this paper we investigate the effect of the phloem‐specific expression of pyrophosphatase on phloem metabolism, and on plant growth and allocation. A small decrease in the hexose phosphate/UDP‐glucose ratio, the ATP/ADP ratio and the respiration rate in the midribs of the transformants provides evidence Hint mobilization of sucrose via pyrophosphate‐dependent reactions is necessary for phloem energy metabolism. The source leaves of the transformants had higher levels of carbohydrates and amino acids and a much higher glutamine/glutamate ratio than the wild type, showing that export was inhibited and that the growth inhibition was not due to a lack of photoas‐similates or organic nitrogen in the leaves. The accumulation of photoassimilates was paralleled by a decrease in photosynthesis, chlorophyll content and ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity, a small increase in hexose phosphates and triose phosphates and a decrease in glycerate 3‐phosphate in the source leaves. There was a decrease of soluble sugars and amino acids in sink leaves of the transformants. In sink leaves amino acids decreased more than carbohydrates and a decrease in the glutamine/ glutamate ratio was observed. This was accompanied by a large decrease of nitrate. Sugars and amino acids were also reduced in the root tips of the transformants. The carbohydrate /amino acid ratio decreased 5‐fold in the root tips, indicating a particularly smile shortage of carbohydrates. Relatively high levels of sugars and amino acids in the basal regions of the root and the increase in sugars in the midrib indicate that there is also increased leakage of assimilates out of the phloem during long‐distance transport. Metabolism is required to maintain phloem function along the transport route, as well as for the initial step of loading. The transformants showed decreased stem and root growth. The growth inhibition was largest in conditions allowing rapid growth of the wild type (high light and nitrogen supply).
Physiological and biochemical changes related to methyl jasmonate‐induced chilling tolerance of rice (Oryza sativa L.) seedlings
Authors: LEE T.‐M. , LUR H.‐S. , LIN Y.‐H. , CHU C. 
Published: April 2006

ABSTRACTPhysiological and biochemical changes related to methyl jasmonate (MeJA)‐induced chilling tolerance of rice (Oryza sativa L. cv. Taichung Native 1) seedlings were investigated. Treatment of whole plants with 10 mmol m−3 MeJA for 48 h before chilling (5 °C) was optimal for the induction of chilling tolerance. MeJA greatly improved the survival ratio of chilled seedlings and ameliorated chilling injury such as demolition of membrane structure (estimated by electrolyte leakage). MeJA also prevented water loss in chilled seedlings by reducing the opening of stomata and decreasing the root bleeding rate. Putrescine and spermine levels in shoots increased but spermidine levels decreased on exposure to MeJA. In roots, putrescine levels also increased and spermidine levels increased transiently on exposure to MeJA. Activities of arginine decarboxylase (ADC; EC 4.1.1.19) and S‐adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.50) in both shoots and roots increased on exposure to MeJA, while the activity of ornithine decarboxylase (ODC; EC 4.1.1.17) remained unchanged. The MeJA‐induced putrescine increase was inhibited by 50 mmol m−3α‐difluoromethylarginine (DFMA), an irreversible inhibitor of ADC, but not by 50 mmol m−3α‐difluoromethylornithine (DFMO), an irreversible inhibitor of ODC. The effect of MeJA on the induction of chilling tolerance was also reduced by 50 mmol m−3 DFMA. The effects of DFMA were partly prevented by 1 mol m−3 putrescine. This indicates that putrescine accumulation is required for the induction of chilling tolerance of rice seedlings by MeJA.
Effects of light regime on δ13C, photosynthesis and yield of field‐grown banana (Musa sp., Musaceae)*
Authors: ISRAELI Y. , SCHWARTZ A. , PLAUT Z. , YAKIR D. 
Published: April 2006

ABSTRACTBanana plants (Musa sp., Musaceae) were grown for 2 years in the field in 12×20m plots under irradiance levels incident upon the canopy of 100, 81, 62 and 32% of sunlight. Time‐integrated parameters such as leaf δ13C, yield and leaf mass to area ratio were linearly correlated with irradiance level (R2>0.9). In contrast, midday CO2 assimilation and transpiration efficiency (A/g) decreased significantly and substomatal CO2 concentrations (cst) increased significantly only at the lowest irradiance levels (below 81% irradiance). Diurnal gas exchange measurements indicated that the linear response of the long‐term parameters may be associated with the significant variations in photosynthetic activity among the irradiance treatments observed only in the early morning hours. The linear fit between yield and irradiance level (per cent of control) had a slope of 0.82 (with apparently constant yield to biomass ratio). These results directly demonstrate the significance of variations in incident light, such as may be associated with increasing cloudiness, on productivity of tropical plants such as the banana. The importance of using time‐integrated indicators in general, and the reliability of using 13C discrimination in particular, in evaluating the responses of plants to changes in incident irradiance is demonstrated.
Glucose feeding of intact wheat plants represses the expression of a number of Calvin cycle genes
Authors: JONES P. G. , LLOYD J. C. , RAINES C. A. 
Published: April 2006

ABSTRACTThe photosynthetic capacity and Rubisco levels of primary wheat leaves were reduced significantly in plants grown on media supplemented with 1 % glucose. Neither the chlorophyll content nor the growth rate of the primary leaf was affected by this treatment. In glucose‐fed plants a decrease in levels of mRNA encoding several Calvin cycle enzymes (fructose 1,6‐bisphosphatase, sedoheptulose 1,7‐bisphosphatase, phosphoglycerate kinase and Rubisco Small Subunit) was found to correspond to an increase in the internal levels of glucose. In control plants endogenous levels of glucose and sucrose were measured in leaf sections from the base to the tip of the primary leaf, which revealed a gradient of each of these sugars within the leaf, with the highest levels at the tip. Conversely, Calvin cycle transcripts were seen to decrease in the oldest tip sections. In glucose‐fed plants, the endogenous glucose levels were increased throughout the leaf but Calvin cycle RNA levels were most markedly reduced in the mid‐leaf section. These data indicate that the changing metabolic status of the cells from the base to the tip of the primary wheat leaf may play a role in the regulation of Calvin cycle gene expression during normal leaf development.
Exchange diffusion of alkali ions through the apoplast of the potato (Soianum tuberosum L.) storage parenchyma
Authors: MICHAEL W. , EHWALD R. 
Published: April 2006

ABSTRACTInterdiffusion coefficients of K and Na for tangential transport through cell walls were found to be independent of ion strength and only moderately (c. 50%) lower than values known for diffusion in water. Although at low salt concentrations alkali ion exchange diffusion on the cell wall pathway is facilitated by accumulation of diffusing species in the Donnan space, at all concentrations the resistance of the whole tissue for apoplastic cation exchange diffusion remained significantly higher than that of unstirred liquid of equal thickness, as the area fraction of the cell wall pathway in the parenchyma is small.
Influx and efflux of inorganic carbon in Synechococcus UTEX625
Authors: SALON C. , MIR N. A. , CANVIN D. T. 
Published: April 2006

ABSTRACTThe CO2 and HCO3− fluxes in air‐grown cells of Synechococcus UTEX 625 al pH 8‐0 were measured during dark to light and light to dark transitions using a mass spectrometer and sampling of the reaction medium. The kinetic parameters for initial uptake of CO2 and HCO3− were determined during the initial period of illumination. The development of the internal Ci pool was followed up to steady‐state photosynthesis, which occurred when the size of the internal inorganic carbon pool remained apparently constant for a limited period. The experimental procedure confirmed that only CO2 transport occurred with 100mmolm−3 Na+ and that both CO2 and HCO−3 transport occurred with 25molm−3 Na+. The K1/2 values of initial CO2 and HCO3 uptake were 0.7 and 17.2 mmolm−3respectively and agreed closely with the K1/2 values of net CO2 and HCO3− transport during steady‐state photosynthesis, which were 0.66 and 17.1 mmolm−3 respectively. Maximum rates of CO2and HCO3− transport were 423 and 219mmolh−1 g−1 Chl. Maximum CO2 efflux observed upon darkening was 118mmolh−1 g−1 Chl. A permeability coefficient of the cell for CO2 of 3 × 10−8 m s−1 was determined from the dark CO2 efflux assuming an internal pH of 7.2 in the dark. Following the initial CO2 uptake in the light, the extracellular [CO2] steadily declined when only CO2 transport was allowed, but an increase in the extracellular [CO2] when HCO3− transport was allowed to proceed suggested that an enhanced CO2 efflux occurred as a result of the larger size of the intracellular Ci pool.
HCO3− and CO2 leakage from Synechococcus UTEX 625
Authors: SALON C. , MIR N. A. , CANVIN D. T. 
Published: April 2006

ABSTRACTThe leakage of various inorganic carbon species from air‐grown cells of Synechococcus UTEX 625 was investigated after a light to dark transition or during a light period using a mass spectrometer under a wide variety of experimental conditions. Total inorganic carbon efflux and CO2 efflux during the initial period of darkness were measured with or without carbonic anhydrase in the reaction medium respectively. The HCO3− efflux after a light to dark transition was estimated by difference. Carbon dioxide efflux in the light was measured by inhibiting CO2 transport with either Na2S or COS3 or quenching the 13C inorganic carbon transport by the addition of 12C inorganic carbon in excess. In cells in which CO2 fixation was inhibited, when only the HCO3− transport system was fully operative, CO2 effluxed continuously during the light period at a rate equal to about 25% of that in darkness. When only the CO2 transport system was operative, HCO3− effluxed during the light period. The difference between the light and dark efflux rates was consistent with a 0.6 unit decrease in the intracellular pH upon darkening the cells. The permeabilities of the cell for CO2 (2.94 ± 0.14 ± 10−8ms−1; mean ± SE, n=137) and HCO3− (1.4–1.7 ± 10−9 ms−1) were calculated.
The involvement of the transpirational bypass flow in sodium uptake by high‐ and low‐sodium‐transporting lines of rice developed through intravarietal selection
Authors: YADAV R. , FLOWERS T. J. , YEO A. R. 
Published: April 2006

ABSTRACTWe report the characterization of high‐ and low‐sodium‐transporting lines developed by intravarietal selection within a cultivar, IR36, of rice (Oryza sativa L.). The purpose was to investigate the mechanistic basis of sodium uptake in material in which differences in salt uptake could be isolated from the many other morphological and physiological characteristics that affect the phenotypic expression of salt tolerance. The lines differed in mean sodium transport by a factor of 2. They differed in vigour and water use efficiency, which are characters that modify the effects of salt transport, by only 12% or 13%. The lines did not differ significantly in other physiological traits that are components of salt resistance: compartmentalization at the leaf and cellular levels. There was a strong correlation between the transport of sodium and a tracer for apoplastic pathways (trisodium, 3‐hydroxy‐5,8,10‐pyrene trisulphonic acid, PTS) in both lines. The regression coefficient for sodium transport on PTS transport was the same in both lines. The individual variation in PTS transport was similar to that in sodium transport, and the variation in the transport of both was very much greater than the variation in any other character studied. The high‐sodium‐transporting line took up proportionately more PTS than the low‐sodium‐transporting line. It is concluded that the transpirational bypass flow is of major importance in sodium uptake by rice and that selection for differences in sodium transport has been brought about by selection for heritable differences in the bypass flow.