bluuebunny/crossref_metadata_2025_split huggingface dataset:
Xylem development in relation to water uptake by roots of grapevine (Vitis vinifera L.)
Authors: MAPFUMO E. , ASPINALL D. , HANCOCK T. , SEDGLEY M. 
Published: April 2006

SUMMARYAxial resistance (Ra) was estimated from xylem diameter measurements obtained from periodic acid and toluidinc blue O (PAS‐TBO) stained sections of Vitis vinifera L. ev. Shiraz. Multiple linear regression showed a strong negative relationship between axial resistance and either root diameter or distance from the root tip. Water stress treatments did not affect the relationships, but plant age significantly influenced the intercept of the regression. The use of both lignin and cytoplasm stain showed that some vessels retained degenerating protoplasm which would impede water flow. Inclusion of these vessels in calculations of axial resistance could account for the underestimation reported by some authors in comparison with experimental determinations. Calculations based on the assumption that all xylem vessels, large and small, are involved in axial water conduction showed that use of mean xylem diameter might result in overestimating values by a magnitude of between 1.7 and 4.4. The use of individual xylem vessel diameters gave more accurate estimation of axial resistance. Some adjacent secondary xylem and metaxylem vessels were observed to merge into single vessels as a result of breakdown of the wall between them. Implications of such a developmental phenomenon are discussed.
Photosynthesis and nutrient supply in needles of Sitka spruce [Picea sitchensis (Bong.) Carr.]
Authors: CHANDLER J. W. , DALE J. E. 
Published: April 2006

SUMMARYGrowth and photosynthetic development were measured for currently developing needles of young trees of Sitka spruce [Picea sitchensis (Bong.) Carr.] throughout their fourth growth season. Treatments included trees that were fully fertilized (control), trees deficient in phosphorus (–P), or nitrogen (–N), and trees initially deficient but then supplied with phosphorus (–PR) or nitrogen (–NR). Growth was measured in terms of needle projected area, and the photosynthetic components measured were pigment concentration, net photosynthetic rate, (PN), activity of ribulose‐1,5‐bisphosphate carboxylase, (RuBPC), stomatal conductance to CO2, (Gs), and the intercellular partial pressure of CO2, (Ci). Needle growth was rapid, beginning in early May and being complete by the end of the month or early in June. Free growth occurred in the –NR treatment. Photosynthesis increased throughout the season, reaching a peak in August, with some variables subsequently showing a decrease in value. PN increased more rapidly during needle expansion than either chlorophyll concentration or RuBPC activity. Phosphorus deficiency led to a reduction in RuBPC activity, which was restored to the control value following Refertilization with P. Nitrogen deficiency severely reduced values of all variables studied, except Ci, which was higher than for the controls. Refertilization of –N trees caused a very rapid increase in values of all variables, with an increase in Ci, representing a larger increase in mesophyll conductance to CO2, (GM), than GS, PN and RuBPC activity were significantly correlated with total chlorophyll concentration for all treatments, but PN was not correlated with GS or RuBPC activity.
Nitrogen uptake, partitioning and internal cycling inPicea sitchensis(Bong.) Carr. as influenced by nitrogen supply
Authors: MILLARD P. , PROE M. F. 
Published: April 2006

SUMMARYFour‐year‐old seedlings ofPicea sitchensis(Bong.) Carr. were grown in sand culture throughout 1989 and irrigated with nutrient solutions containing either 1.0 mol N m−3(Low N) or 6.0 mol N m−3(High N), to precondition their growth and capacity for N storage. During 1990 N enriched with15N was supplied, either from 15 March to 27 June, or 28 June to 20 November. Recovery of unlabelled N was used to determine the storage and immobilization of N for foliage growth, and the partitioning of labelled N taken up during the two periods was measured.Initial growth of trees in 1990 was unaffected by the current N supply and determined only by the N supplied the previous year. High N throughout increased the number of needles grown in 1990 compared to low N‐treated trees, but had little effect on the dry weight of individual needles. When preconditioned with High N, trees responded to Low N in 1990 by a reduction in needle dry weight, without altering the number of needles produced. Low N trees supplied with High N in 1990 responded by increasing both needle numbers and dry weight, compared with trees supplied with Low N throughout. The amount of unlabelled N remobilized to foliage growth in 1990 was unaffected by the current N supply but reflected the amount of N in store, as determined by the N supply the previous year. The majority of N was remobilized from the 1989 foliage and none from roots. Partitioning of labelled N taken up during 1990 altered during the year, with a greater proportion of N taken up after 28 June recovered in the roots in all treatments, due to root growth as opposed to allocation of N to storage during the autumn, since root N concentrations fell between 17 June and the final harvest on 20 November.
Modification of the Fe protein of the nitrogenase of Gloeothece (Nägeli) sp. ATCC 27152 during growth under alternating light and darkness
Authors: DU CAIGAN , GALLON JOHN R. 
Published: April 2006

SUMMARYThe Fe protein of the nitrogenase of the unicellular Cyanobacterium Gloeothece (Nägeli) sp. ATCC 27152 can be resolved by SDS–PAGE into two antigenically detectable components of approximate Mr 38500 and 40000 respectively. The larger form of this protein may be produced by modification of the smaller form. Modification of the Fe protein is promoted under conditions where O2 (but not O2− or H2O2) has increased access to the enzyme, but does not allow nitrogenase to function under conditions of O2 stress.During growth of Gloeothece under alternating light and darkness, antigenically detectable Fe protein is absent throughout most of the light period. The restriction of nitrogenase activity to the period of darkness is better explained in terms of regulation of nitrogenase synthesis and degradation than by reversible modification of a constant intracellular concentration of Fe protein. However, newly synthesized Fe protein always appeared initially as its larger form, which may be catalytically inactive in aerobic cultures of Gloeothece. Conversion of this form to the smaller, assumed active, form of the Fe protein may be an additional factor in explaining the increase in nitrogenase activity that occurs during the first few hours of each dark phase.
The effect of fungicides on vesicular–arbuscular mycorrhizal symbiosis
Authors: SUKARNO N. , SMITH S. E. , SCOTT E. S. 
Published: April 2006

SUMMARYThis paper describes the effects of the fungicides Benlate, Aliette and Ridomil on plant growth and on mycorrhizal development in onion plants. An attempt was made to distinguish effects on plants from those on the fungus by making comparisons between mycorrhizal plants in the absence of added phosphorus and non‐mycorrhizal equivalent size plants. Vital staining techniques were used to analyse the effects of the fungicides on the living fungus both within the root and in the soil.Benlate had no effect on shoot dry weight or root length of onion plants whereas a reduction in plant growth was observed following the application of Aliette or Ridomil, in comparison to control plants. Benlate had negative effects on the numbers of living internal hyphae, arbuscules, fungal‐plant interface and living external hyphae in the soil.Aliette had no effect on the number of living intercellular hyphae and arbuscules. However, it markedly reduced the root length and the length of infected root per plant. These combined effects led to a reduction in the area of the interface between fungus and plant. The length of external hyphae per gram of soil was reduced following the application of Aliette, though not as severely as with Benlate.Ridomil had more complex effects on vesicular‐arbuscular mycorrhizal symbiosis; treated plants showed a reduction in plant growth and also a reduction in all fungal parameters, namely the number of living intercellular hyphae, arbuscules and fungal–plant interface, the length of infected root and the development of external hyphae in the soil.
CO2 fluxes of cryptogamic crusts
Authors: JEFFRIES D. L. , LINK S. O. , KLOPATEK J. M. 
Published: April 2006

SUMMARYThe relationship between carbon dioxide exchange of Microcoleus‐ and Scytonema‐dominated cryptogamic crusts and resaturation time was measured in the laboratory with a modified discrete sampling technique and infrared gas analysis. Maximum net photosynthetic rate of Microcoleus was 187 nmol CO2m−2s−1 and of Scytonema was 111 nmol CO2m−2s−1 for rehydration to 100% soil saturation. Both crust types demonstrated a slow rise in resaturation respiration and took 2 days to become fully active after the (first rehydration to 100% soil saturation after long‐term dryness, and only one day to become active after the second rehydration cycle.
A detailed early postglacial (Flandrian) pollen diagram from Cwm Idwal, North Wales
Authors: TIPPING RICHARD 
Published: April 2006

SUMMARYPalynological investigation of lacustrine sediments in Llyn Idwal, in the uplands of Snowdonia, North Wales, has shown that pollen assemblages predating those at the base of Godwin's (1955) pollen diagram are recorded. These earlier pollen assemblages do not, however, indicate a revision of the Loch Lomond Readvance age of the last glaciers to occupy the cwm, Arctic‐alpine flora presently growing on the cliffs of Cwm Idwal colonized the catchment as pioneer communities in the earliest postglacial, immediately following ice decay, but appear to have been driven to their present niches very early in the postglacial. Their subsequent reappearance is explained by natural or anthropogenically induced instability in local woodland, or perhaps by increased erosion and stream How affecting pollen transport from cliffs. Evidence is presented of a brief period of arid climate during the expansion of Juniperus, at around 10000 BP.
Altitudinal variation in the response of the vegetation to Late‐glacial climatic events in the northern French Alps
Authors: DAVID FERNAN 
Published: April 2006

SUMMARYPollen and macroscopic plant remains were studied at eight neighbouring sites, in order to define Late‐glacial vegetational history in the northern French Alps. Local pollen assemblage zones are described and indicate that the main elements of vegetational history combine the features of adjacent regions. Herb pollen assemblages are similar to those recorded in the Swiss Late‐glacial, whereas the early occurrence of shrubs and trees is typical of the southern French Alps. An early effect of altitude on vegetation distribution is demonstrated at the end of the Oldest Dryas. At that time the landscape consisted of a patchwork ofArteimisia–Chenopodiaceae steppe, with shrubs in hollows and valleys.Betulawas recorded up lo 700 in andJuniperusup to 1300 m. This altitudinal variation became more pronounced with the arrival of new species. During the Alleröd, mixed stands ofBetulaandPinuswere present up to an altitude of about 1000–1300 m, withBetulareaching 1700 m, this limit depending on factors such as exposure and continentality. The Younger Dryas oscillation is clearly recorded, as at more oceanic N.W. European coastal margins. Nevertheless, the record of the vegetation response to climatic change depends on the elevation of the studied sites. The limit ofPinusstands fell to 700–1000 m. At a lower altitude the climatic signal is weaker and alders [Alnus glutinosa(L.) Gaertn,Alnus incana(L.) Moench] began to spread. Continuous occurrences of alder owing to regional pollen transport are detected up to the highest sites. The empirical limit ofAlnusis therefore proposed as a biostratigraphic marker of the Younger Dryas in the area. Finally. The possibility of a climatic deterioration that started during the late Alleröd is discussed on the basis of absolute chronology.
Cells and tissues in the vegetative sporophytes of early land plants
Authors: EDWARDS DIANNE 
Published: April 2006

SUMMARYRemarkable preservation in coalified and pennineralized fossils from Upper Silurian and Lower Devonian sediments deposited some 420 to 390 million years ago provides insight into the major anatomical innovations associated with the early stages in the colonization of the land by higher plants. Using uniformitarian principles, such information, combined with gross morphology, can then be used to reconstruct the pioneers as growing, metabolizing and reproducing organisms, as well as allowing assessment of affinity, although apart from the lycophytes, they have no close relationship with extant groups. In considering vascular tissues, diversity is exemplified by descriptions of the metaxylem in protosteles of Zosterophyllopsida and Drepanophycopsida (putative lycophytes), ofPsilophyton(Trimerophytopsida), of the Rhyniaceae (includingRhynia gwynnevaughanii, certainTaeniocradaspp.,Sennicaulis) and ofCooksonia pertoni, a Lower Devonian representative of the organization found in the oldest pteridophyte‐like land plants.Aglaophyton majoris included as a plant with bryophyte‐like vascular tissues in a branching sporophyte with cuticle, stomata and intercellular space system typical of the homoiohydric tracheophyte. In all water‐conducting cells, interpretation of the primary and secondary wall results from comparisons involving the anatomy and chemistry of extant examples and an understanding of taphonomic processes. Phloem is only rarely preserved and usually identified from its position around the xylem. In contrast, dermal features are better known, because of penetration of the resilient cuticle between epidermal cells. They appear conservative. Thus stomata with two guard cells look remarkably similar to extant forms in surface view, and by consideration of their relationship with surrounding epidermal cells and of extent of cuticularization, seem to have operated in a similar way to those in certain mosses and ferns. Cuticular ornamentation (papillae, striations) and epidermal outgrowths (unicellular and multicellular) are described and their adaptive significance conjectured. Ground tissue systems are best preserved in Rhynie Chert permineralizations where zonation of the cortex is tentatively related to photosynthetic and structural roles. The latter function is also attributed to thick‐walled, outer cortical cells recorded in many zosterophylls and inPsilophyton, although the chemical nature of the walls themselves remains equivocal. Problems of identification of roots in plants possessing axial organization with exarch xylem, and in leafy plants with smooth lateral branching systems are briefly addressed. Finally axis apices inRhynia givynne‐vaughaniiand sections showing stages in the maturation ofAsteroxylonstems are described from the Rhynie Chert.ContentsSummary225I.Introduction226II.Vascular systems226III.Dermal systems237IV.Ground tissue systems241V.Apical meristems244VI.Distinction of aerial stems, rhizomes and roots245VII.Why anatomy?245Acknowledgements245References245
Plant response to irrigation with water enriched with carbon dioxide
Authors: ENOCH H. Z. , OLESEN J. M. 
Published: April 2006

SUMMARYThe influence of irrigation with CO2‐enriched water on plant development and yield is reviewed. The reason for irrigation with CO2‐enriched water was – in most cases – to increase yield. The present evaluation considers results from over a hundred studies performed since the first experiment in 1866. Special emphasis is given to the comparison of 85 experiments made by Mitscherlich in 1910 with 358 irrigation experiments made in the last 80 years. In a statistical analysis of these experiments, the measured plant parameter (often growth and/or gas exchange rates) showed a highly significant mean increase of 2.9 % in plants irrigated with CO2‐enriched water as compared with control.Evidence of five mechanisms was found. The subterranean carbon dioxide concentration influences: (a) the rate of nitrification and hence of nitrogen availability; (b) the rate of weathering and pH, and hence the availability of other plant nutrients; (c) the CO2 uptake via roots into the transpiration stream, contributing to the rate of leaf photosynthesis; (d) the hormone levels in the plant; and (e) the rate of pesticide decomposition in soils.After examining the available evidence we found that (a) and (b) in some experiments are important to plant growth, since they change the physiochemical environment of the roots. On the other hand, while (c) could theoretically contribute up to 5% of plant carbon assimilation, it usually contributes less than 1 %, while (d) contributes most of the observed effects of CO2‐enriched water on plants. In addition, pesticide decomposition in soils can be delayed by supra‐ or sub‐optimal CO2 concentrations.

Contents

Summary
249

I.
Introduction
249

II.
Historical background
250

III.
Methods for comparing experimental data
251

IV.
Analysis of yield ratios
251

V.
Temporal and spatial changes in the soil atmosphere during and after irrigation with CO2‐enriched water
252

VI.
Mechanisms through which irrigation with CO2‐enriched water influences yield
253

Acknowledgements
256

References
257
Structure and expression of genes coding for structural proteins of the plant cell wall
Authors: JOSÈ MATILDE , PUIGDOMÈNECH PERE 
Published: April 2006

SUMMARYThe best‐known protein components of the plant cell wall have highly repetitive, proline‐rich sequences. The use of recombinant DNA approaches has enabled complete sequences of these proteins to be determined and features of the expression of the corresponding genes to be examined. These results, coupled with the use of immunological techniques, have shown that proline‐rich proteins are interesting probes to study developmental and defence processes in plants. In this review, the sequence and expression of different groups of proline‐rich proteins in plants are presented. These groups include hydroxyproline‐rich glycoproteins (HRGP) or extensins, proline‐rich proteins (PRP) and glycine‐rich proteins (GRP). The specific features of each group and the possible functions of these proteins are discussed, as well as the data available on the mechanisms controlling the expression of their corresponding genes.

Contents

Summary
259

I.
Introduction
259

II.
Hydroxypioline‐rich glycoproteins (HRGPs)
261

III.
Proline‐rich proteins (PRPs)
270

IV.
Glycine‐rich proteins (GRPs)
274

V.
Concluding remarks
277

References
279
Cloning symbiosis‐related cDNAs from eucalypt ectomycorrhiza by PCR‐assisted differential screening
Authors: TAGU D. , PYTHON M. , CRÉTIN C. , MARTIN F. 
Published: April 2006

SUMMARYAs part of a project to identify symbiosis‐related genes, we report here a simple differential screening procedure for isolating up‐ and down‐regulated fungal transcripts from a cDNA library of the developing Eucalyptus globulus‐Pisolithus tinctorius mycorrhiza. cDNA inserts of randomly selected λZAP plaques were amplified by PCR and separated by agarose gel electrophoresis. The PCR‐amplified cDNA samples were then screened by Southern blotting, using radiolabelled‐cDNA probes of high specific activity. We have applied this method to fungal transcripts that are differentially expressed in ectomycorrhizas during the early stages of development. We estimate that about 50 % of the fungal mRNA population is regulated by development of the symbiosis; several up‐ and down‐regulated cDNAs have been isolated for further analysis.
Adverse effects of nitrate on stem nodules of Sesbania rostrata Brem*
Authors: KWON DUCK‐KEE , BEEVERS HARRY 
Published: April 2006

SUMMARYWhen the stems of Sesbania rostrata, growing vigorously in nutrient solution, are inoculated with Azorhizobium caulinodans ORS 571 and deprived of nitrate, hundreds of nodules with active N2 fixation (acetylene reduction) develop on each stem within 10 d. The numbers of nodules that develop are not affected by increasing the nitrate concentration in the medium from 0 to 9 mM. However, as the nitrate concentration is raised above about 2 mM the growth of the nodules is strongly inhibited and all aspects of acetylene reduction activity (ARA) are progressively curtailed as the nitrate concentration is increased from zero. In 6 mM nitrate, effects are seen at the earliest possible time of measurement (6 d after inoculation) with maximum inhibition of growth and ARA (about 80%) at 10 d. In plants with stem nodules that have developed in the absence of nitrate since inoculation, the addition of 9 mM nitrate leads to inhibition of further nodule growth and to prompt decrease in specific ARA. The ‘growth’ and ‘activity’ responses of the stem nodules of Sesbania are similar in degree and sensitivity to those of root nodules of other legumes and thus they can no longer be considered as resistant to fixed N.
Uptake and assimilation of nitrite in the acidophilic red alga Cyanidium caldarium Geitler
Authors: FUGGI AMODIO 
Published: April 2006

SUMMARYThe acidophilic red alga, Cyanidium caldarium Geitler, could use nitrite as a nitrogen source for growth, although this compound was very toxic in acidic media. Growth could be sustained when nitrite was added continuously at a rate lower than the maximum rate of nitrite assimilation for the culture. Nitrite assimilation was derepressed in cells growing on nitrate or nitrite, under nitrogen limitation and by nitrogen starvation. Ammonium‐grown cells showed a limited capacity for nitrite reduction in the light, even if nitrite reductase was not detectable in cell extracts. In acidic media nitrite was taken up mainly through HNO, influx. Nitrite assimilation, in viva, was restricted by a saturable step under conditions in which nitrite uptake was not limiting. The pH of the cell suspension affected nitrite assimilation by changing the K½ over the pH range tested but not the Vmax. The K½ was inversely proportional to the concentration of H+ in the medium. The apparent Km value for nitrite of nitrite reductase, in vitro, and its expected apparent Km value, in vivo, estimated from the K½ of nitrite assimilation, suggested that the activity of this enzyme may not be the limiting step of nitrite assimilation.
Visualizing the distribution of elements within barley leaves by energy dispersive X‐ray image maps (EDX maps)
Authors: WILLIAMS M. L. , THOMAS B. J. , FARRAR J. F. , POLLOCK C. J. 
Published: April 2006

SUMMARYX‐ray image maps of transverse sections of barley leaf blades were compared with individual X‐ray emission spectra from vacuoles of barley leaf mesophyll, epidermis and parenchymatous bundle sheath cells. Both forms of X‐ray analysis revealed distinct patterns in element distribution within the leaf blade. Calcium and Cl predominated within the epidermal cell vacuoles whilst P appeared mainly in the mesophyll cell layer. Apparent accumulation of S and Mg within the bundle sheath cell vacuoles is discussed in relation to xylem unloading and sulphur assimilation.