bluuebunny/crossref_metadata_2025_split huggingface dataset:
Initial association between Helianthemum and Terfezia is enhanced by low iron in the growth medium
Authors: KAGAN‐ZUR VARDA , RAVEH ERAN , LISCHINSKY SMADAR , ROTH‐BEJERANO NURIT 
Published: April 2006

summaryActivated charcoal added to artificial growth medium enhances initial association between the mycelium of the desert truffle Terfezia leonis Tul. and the roots of Helianthemum sessiliforum (Defs). Pers. in vitro. This is due, at least in part, to adsorption of iron.
Characterization of developmental phases of the woody perennial shrub, Solanum aviculare Forst.
Authors: JAMES A. C. , MANTELL S. H. 
Published: April 2006

summaryDevelopmental phases which occur during the growth of seedlings through to flowering in the woody perennial shrub, Solanum aviculare Forst., were characterized. Bud position, as determined by nodes and height to flower, was correlated with the characteristics of heterophylly, leaf anatomy, phyllotaxy, diameter of the shoot apex, dry matter content and chlorophyll content. The existence of developmental phases was confirmed by comparing the performances of axillary buds of the pre‐ and post‐flowering (anthocladial shoots) phenotypes which were either left to develop in situ, following decapitation of plants, or ex situ on subsequently rooted severed shoots (ramets). Performances of in situ buds differed from ex situ buds in both adults and juveniles, indicating that flowering had not been initiated prior to excision. Ramets and shoots derived from the ninth node above the cotyledons of seedlings required similar nodes and heights above their own root systems before phase change occurred; the excision and rooting of axillary buds from these positions did not appear to promote maturation in terms of nodes and height to flower. Conversely, the excision of anthocladial axillary buds promoted floral induction when compared to the performance of their counterpart buds which developed in situ, indicating a difference in competence of juvenile and mature anthocladial buds.
Cytoplasmic polarity and endoplasmic microtubules associated with the nucleus and organelles are ubiquitous features of food‐conducting cells in bryoid mosses (Bryophyta)
Authors: LIGRONE ROBERTO , DUCKETT JEFFREY G. 
Published: April 2006

summaryAn ultrastructural survey of food conducting cells in the gametophytes and sporophytes of bryoid mosses, including the highly specialized leptoids of Polytrichales, has revealed that, without exception, these cells have a polarized organization and contain an axial system of endoplasmic microtubules (MTs). The orientation of polarity is highly consistent with the putative direction of the source to sink gradient, with distal cellular ends, i.e. those toward the sink, containing denser cytoplasm than proximal ends. In most cases the nucleus is spindle‐shaped and also lies at the distal end. Longitudinal arrays of MTs are associated with the nuclear envelope. These MTs extend into the cytoplasm for long distances and may come into contact with the plasma membrane lining the terminal walls at the distal ends. Cortical MTs are absent. The endoplasmic MTs are closely associated with a variety of organelles including mitochondria, plastids. endoplasmic reticulum and membrane‐bounded tubules and vesicles. The organelles aligned along the MT bundles lie within longitudinal cytoplasmic strands clearly visible with light microscopy. The discovery of cytoplasmic polarity and endoplasmic MTs as distinctive features of food conducting cells of mosses sets these cells apart from the sieve elements of vascular plants. The MT‐organelle associations, as observed in the food conducting cells of mosses, are hitherto undescribed in plants but are reminiscent of MT arrays functioning in organelle transport in neuronal axons and other animal and fungal systems.
Tansley Review No. 74 Control of organogenesis at the shoot apex
Authors: LYNDON ROBERT F. 
Published: April 2006

summaryThe processes involved in the formation of primordia on the shoor apex are those controlling (1) growth rate, (2) division plane. (3) surface microstructure, and (4) extensibility of the surface. Changes in growth rate and division planes may accompany primordium formation but are considered as probably not in themselves being causal. Changes in surface microstructure may be necessary to delimit the position and area occupied by an incipient primordium. However, attention is directed to changes in surface extensibility as perhaps being the overriding factor in primordium formation. Nevertheless, the position and form of the primordia will also depend on growth rate, division plane, and surface microstructurc being permissive. The relative importance of these four sets of processes may differ from species to species and from one stage of development to another. Chemical and metabolic changes within the apex may first be necessary to determine whether the surface can extend sufficiently for any primordia to form at all, but their positions and time of initiation may depend more on the other factors. The surface microstructure may become more important when patterning is detailed and precise as it is in the developing flower, whereas a less precise mechanism dependent on localized induction of synthesis of a morphogen (auxin?) may provide sufficient information to determine the general position and liming of primordium initiation in vegetative apices. In determining the pattern of primordia on the apex, primordial area at initiation is important and reasons for believing that auxin may be involved in determining this are summarised. The different developmental pathways of primordia seem to diverge from the moment of initiation. Developmental fate of primordia is determined by the hamcotic genes which may in fact be heterochronic genes. How these regulatory genes control the processes involved in differentiation of different types of primordia is so far unknown.

Contents

Summary
1

I.
Introduction
2

II.
The mechanism of primordium formation: what causes an outgrowth of the apical surface?
2

III.
The positions of successive primordia: what determines their size and localization, so giving rise to pattern?
11

IV.
What determines the developmental pathways of the primordia once initiated?
13

V.
Conclusions
15

VI.
Acknowledgements
16

VII.
References
16
The vascular architecture of the fruit receptacle of red raspberry determined by 3D NMR microscopy and surface‐rendering techniques
Authors: WILLIAMSON B. , GOODMAN B. A. , CHUDEK J. A. , HUNTER G. , LOHMAN J. A. B. 
Published: April 2006

summaryThe three‐dimensional structure of the vascular system in tht fruit receptacle of red raspberry was determined using NMR microscopy in combination with computer techniques which highlight the surfaces of specific tissue types. The surface‐rendering technique is particularly valuable in situations, where there are large differences in image characteristics between the tissue of interest and the rest of the specimen, and thus ideal for the delineation of ilic vascular tissue in the raspberry receptacle. This was shown to consist of a conical network of bundles with a spiral pattern of gaps; tht carpellury traces emereed from the proximal end of each gap. The inner xylem and outer phloem tissues each appeared as a pair of fused columns in the surface‐rendered images, and each carpellary trace had a separate supply from the xyiern and phloem.
The host‐pathogen system of Gremmeniella abietina (Lagerb.) Morelet and Scots pine; effects of non‐pathogenic phyllosphere fungi, acid rain and environmental factors
Authors: RANTA HANNA , NEUVONEN SEPPO 
Published: April 2006

summaryScots pine seedlings (1‐yr‐old) were inoculated either once, or three times, with the conidia of two saprophytic Honmmema species. After these inoculations, the seedlings were inoculated later with conidia of the pathogenic fungus Gremmeniella abietina (Lagerb.) Morelet. Seedlings received irrigation with simulated acid rain at pH 3, with water of pH 6. or no irrigation, during and after the inoculation treatments, The severity of the symptoms caused by G. abietina, and rhe isolation frequency of endophytic (symptomless) G. abietina and the saprophytes, were measured 11 months after G. abietina inoculation. The isolation frequencies of the two Hormunema species increased significantly in the seedlings inoculated three times with saprophyte conidia. Irrigation treatments did not affect the saprophytes. The disease symptoms caused by G, abietina were positively correlated with tree density. Symptomless G, abietina was isolated most often from the seedlings that had received irrigation at pH b. The isolation frequency was lowest in seedlings with acidic irrigation. The seedlings inoculated three times with conidia of Hormonema sp. 1 had a lower frequency of G. abietina isolations than other seedlings, but the difference was not statistically significant.
The effect of an insect herbivore and a rust fungus individually, and combined in sequence, on the growth of two Rumex species
Authors: HATCHER P. E. , PAUL N. D. , AYRES P. G. , WHITTAKER J. B. 
Published: April 2006

summaryThe chrysomelid beetle Gastrophysa viridula and the rust fungus Urmnyces rumicis both occur on leaves of Rumex crispus and R. obtusifolius. We investigated the effect of beetle grazing or rust infection individually and when combined in sequence on the growth of their hosts in the field. Singly, beetle or rust reduced leaf area and plant biomass; the effect was greater on R. crispus, and rust caused greater damage than the beetle. Beetle grazing with subsequent rust infection caused damage no greater than that caused by rust alone, although on R. obtusifolius damage was greater than that from beetle grazing alone. Rust infection of R. obtusifolius with subsequent beetle grazing produced damage similar to that from other treatments; involving rust infection. In R. crispus this treatment produced the greatest reduction in biomass, The reductions in root and total plant weight from rust infection with subsequent beetle grazing were accurately predicted by a model including the damage produced by beetle and rust alone and the length of time each was present on the plant. This model also predicted accurately the damage to R. obtusifolius from the beetle followed by rust treatment, but over‐estimated by up to 40% the damage to R. crispus. This can be explained mainly by an inhibition of rust infection by beetle grazing.
Distribution patterns of number of nuclei in conidia from heterokaryons of Heterobasidion annosum (Fr.) Bref. and their interpretation in terms of genomic conflict
Authors: RAMSDALE MARK , RAYNER ALAN D. M. 
Published: April 2006

summaryRatios of nuclear genotypes observed in conidia from heterokaryotic strains of Heterobasidion annosum (Fr.) Bref., obtained from pairings between sympatrically derived, sib‐related and non‐sib‐related homokaryons, commonly deviated from 1:1. Ratios were temporally stable, and the genotypes examined could be ranked in a strict dominance hierarchy, linked both to the relatedness of the association partners and to the growth rates of the parental homokaryons. Parental homokaryons and sibrelated heterokaryons produced conidia with a mean number of nuclei of about two, whereas non‐sib‐related‐d heterokaryons produced conidia that were predominantly uninucleate. Moreover, whereas conidia containing more than one nucleus germinated most rapidly when derived from homokaryons or sib‐related heterokaryons, uninucleate conidia germinated more readily if derived from non‐sib‐related heterokaryons. In a study of naturally occurring heterokaryons, distribution patterns of the number of nuclei in conidia were found to be similar to those of the homokaryons. The possible interpretation of these findings in terms of inter‐nuclear genomic conflict is discussed.
Effects of nitrogen on the response of loblolly pine to drought
Authors: GREEN THOMAS H. , MITCHELL ROBERT J. , GJERSTAD DEAN H. 
Published: April 2006

summaryEffects of drought on carbon and nitrogen dynamics and biomass allocation patterns of loblolly pine (Pinus taedaL.) seedlings grown under 4 different nitrogen levels were determined Nitrogen stress caused an increase in root‐shoot ratio. increased Foliar and mot Starch concentration, decreased soluble sugar concentration, and decreased free amino acid concentration in well‐watered seedlings. Drought cent‐rally caused an increase in foliar hexoses and decreases in foliar find root starch and root hexoses. while not affecting foliar free amino acids. However, nitrogen stress arid drought interactedinaffecting carbohydrate pools and seedling morphology. Foliar starch reserves in high‐N seedling were rapidly metabolized under drought, white N‐deficient seedling maintained similar starch concentrations throughout the drought stress cycle. After one drought cycle, the N‐induced difference in root:shoot ratio was no longer significant. These results suggest that N‐stressed seedlings partition a higher percentage of fixed carbon to storage, and that (his storage pool is less available For immediate Use than in seedlings grown under adequate N.
Exposure of Norway spruce to ozone increases the sensitivity of current year needles to photoinhibition and desiccation
Authors: MIKKELSEN T. N. , RO‐POULSEN H. 
Published: April 2006

summaryPhysiological effects of ozone exposure over three consecutive growing seasons on current year needles of Norway spruce were studied in open‐top chambers, during daily Fumigation cycles in the summer, and after the termination of ozone fumigation in autumn 1990. The trees were exposed to two levels of ozone: charcoal filtered air and non‐filtered air to which 30 nl I−1 of ozone was added in three consecutive years from 1988 to 1990, daily from May to September (8 hours a day). Photosynthesis, stomatal conductance, transpiration and chlorophyll fluorescence were studied on selected days. Significant decreases in net photosynthesis and chlorophyll fluorescence (FN/FM) were found during periods with co‐occurrence of high ozone concentrations And high light intensities, indicating interactions between effects of ozone and photoinhibition. After termination of fumigation enhanced rates of photosynthesis were seen in the trees which had been exposed to ozone. A significant decrease in FN/FM was found for twigs from ozone treated trees when exposed to severe desiccation.
Tolerance and co‐tolerance of the grassChloris barbataSw. to mercury, cadmium and zinc
Authors: PATRA JITA , LENKA MAHESWAR , PANDA BRAHMA B. 
Published: April 2006

summaryRaces ofChloris barbataSw. from a mercury‐contaminated site in the vicinity of a chloralkali plant and from a non‐contaminated site were tested for their relative tolerance to mercury, cadmium and zinc. Pre‐rooted tillers of each of the races were grown in calcium nitrate solution, Ca(NO3)2, 4H2O, l gl−1with or without HgCI2(0.001, 0.01, 0.05, 0.1 and mgl−1), CdSO4.8H2O (0.05, 1.0, 2.5 and 5 mg l−1and ZnSO47H2O (1, 5, 10, 20 and 40 mg l−1) for a period of 5 d, Metal tolerance was evaluated by the effects of the metal on root elongation. Races from the contaminated site were found to be metal‐tolerant, as indicated by higher tolerance indices (TIs) than races from the non‐contaminated site. Mercury and cadmium at lower concentrations and zinc at all concentrations stimulated root growth in tolerant races, resulting in a TI of more than 100%. This indicated a requirement of the metal ion for better root growth. Compared to non‐tolerant races, the tolerant races exhibited higher catalase, peroxidase and acid phosphatase activities as well as higher thiol levels. The over‐all study thus indicated that races ofC. barbatafrom the mercury‐contaminated site were not only tolerant to mercury but also co‐tolerant to cadmium and zinc. Biochemical studies provided evidence that the tolerant races were physiologically distinct from the intolerant races.
Tansley Review No. 76 Helper bacteria: a new dimension to the mycorrhizal symbiosis
Authors: GARBAYE J. 
Published: April 2006

summaryThe symbiotic establishment of mycorrhizal fungi on plant roots is affected in various ways by the other microorganisms of the rhizosphere, and more especially by bacteria. This review discusses the case of some of these bacteria which consistently promote mycorrhizal development, leading to the concept of ‘mycorrhization’ helper bacteria (MHBs). Examples of MHB evidence are given from the literature, with special reference to the Douglas fir (Pseudotsuga menzeisii Mirb. Franco) Laccaria laccata Scop, ex Fr. ectomycorrhizal combination which has been more extensively studied.The fungal specificity of some MHBs and the various mechanisms underlying their effect are discussed, considering five hypotheses: effects on the receptivity of the root, effects on the root‐fungus recognition, effects on the fungal growth, modification of the rhizospheric soil, and effects on the germination of the fungal propagule.MHBs are then considered for their ecological and evolutionary implications, and examples of practical applications in forest nurseries are given: when added to the fungal inoculum, MHBs can improve the success of ectomycorrhizal inoculation of planting stocks with fungi selected for their outstanding growth stimulation after outplanting.The conclusion points out a number of fundamental questions which remain unanswered about mycorrhization helper bacteria and suggests some investigation priorities in this new field of mycorrhiza research.

Contents

Summary
197

I.
Introduction
197

II.
Evidence for helper bacteria
198

III.
Fungus‐specificity of MHBs
200

IV.
Mechanisms underlying the MHB effect
201

V.
Ecological and evolutionary implications of MHBs
205

VI.
Practical applications of MHBs
206

VII.
Conclusions and perspectives
208

Acknowledgements
208

References
208
The effects of mycorrhizal infection on components of plant growth and reproduction
Authors: LU XIAOHONG , KOIDE ROGER T. 
Published: April 2006

summaryWe studied the effects of mycorrhizal infection by Glomus etunicatum Becker & Gerd. and P amendment (three levels) on growth and reproduction of Abutilon theophrasti Medic. Mycorrhizal infection increased total leaf area, but individual leaf size was more‐affected than leaf number. Mycorrhizal infection decreased the time taken to initiate flowering, increased the total duration of flowering, and increased seed production by increasing the number of flowers produced, the proportion of flowers producing fruits, and the number of seeds per fruit. Seeds produced by mycorrhizal plants were also heavier and contained more N and P than those produced by non‐mycorrhizal plants, P amendment generally had similar influences to mycorrhizal infection, but seed P content was far more plastic in response TO P amendment than to mycorrhizal infection. The various components of reproduction were not uniformly affected by either mycorrhizal infection or P amendment. The most phenotypically plastic reproductive components were fruit production and seed P content. The least plastic components were seed weight and seed N content.
Effects of O3 on the stomatal behaviour of Egyptian varieties of radish (Raphanus sativus L. cv. Baladey) and turnip (Brassica rapa L. cv. Sultani)
Authors: HASSAN I. A. , ASHMORE M. R. , BELL J. N. B. 
Published: April 2006

summaryThe effects of O2 (80 nl 1−1) on the photosynthetic rate (A) and stormatal conductance (g) of Egyptian varieties of radish (Raphanus sativus L. ev. Baladey) and turnip (Brassica rapa L. ev. Sultani) were examined. Exposure to O3decreased A in both species, while gs was increased in radish and decreased in turnip. The effect of different concentrations of O3, (50, 100, 150 nl l−1 on radish was examined and it was found that A decreased, while g, increased, with increasing concentrations of O3.Scanning electron microscopy (SEM) of fumigated leaves showed that the increase in gs in radish resulted from the collapse of epidermal cells. Counts of the percentage of stomata which were fully open demonstrated that 80 nl 1−1 O3 caused an increase of 18% in radish and a decrease of 14% in turnip. The proportion of opened stomata was found to increase with increasing O3 concentration in radish.
Comparative investigations of cuticular permeability of conifer needles from healthy and damaged trees
Authors: SCHREIBER LUKAS 
Published: April 2006

summaryUsing pentachlorophenol (PCP) and conifer needles, rates of cuticular PCP uptake and effective leaf surface areas were measured, and PCP permeances of the cuticular membranes were calculated. Needles from healthy and damaged conifer trees of the species Picea abies (L.) Karst., Pinus sylvetris L. and Abies alba Mill. were Investigated. Significant differences of the rates of cuticular uptake, effective leaf surface areas and permeances of the cuticular membranes between healthy and damaged trees were not evident. Thus, it must be concluded that damaged cuticular transport harriers of the needles cannot have contributed to the damage symptoms observed with the trees investigated in this study. However, it was found that increasingly older spruce needles had significantly higher permeances, indicating a decrease of cuticular barrier properties with needle age. Additionally, due to larger effective leaf surfaces spruce needles of higher altitudes (1100 m above sea level) possessed higher rates of cuticular transport compared to needles from lower altitudes (400 m above sea‐level). Therefore, these findings might help to understand why older needles and trees growing in higher Geographical sites are more sensitive to detrimental environmental influences causing symptoms of novel forest decline.
Light, chlorophyll, carboxylase activity and CO2 fixation at various depths in the chlorenchyma of Opuntia ficus–indica (L.) Miller under current and elevated CO2
Authors: NOBEL PARK S. , CUI MUYI , ISRAEL ALVARO A. 
Published: April 2006

summaryMature cladodes of Opuntia ficus‐indica (L.) Miller have a thick chlorenchyma (about 4 mm) with a relatively high chlorophyll convent (0.65 gm−2), suggesting that light may be greatly attenuated and hence CO2 fixation negligible in the inner part of this tissue. Indeed, blue light (400–470 nm) and red light (670–685 nm)were 99% attenuated in the outer 2 mm of the chlorenchyma when the cladodes developed under both current and elevated CO2 Concentrations. Nevertheless, the nocturnal acidity increase and 14C accumulation following a brief exposure to 14CO2 at night decreased only 22 to 47% for a layer 2–3 mm deep in the chlorenchyma of this CAM plant. Under a particular growth CO2, the activities of both ribulose‐1,5‐bisphosphate carboxylase/oxygenase and phosho‐enolyruvate carboxylase were similar for each of the outer three 1‐mm‐thick layers of the chlorenchyma. Therefore, although the light level and total chlorophyll decreased sharply with depth and the chlorophyll a/b ratio also decreased. Substantial CO2 fixation apparently occurs throughout most of the chlorenchyma. When O. ficus‐indica was grown under 720 μmol CO2 mol−1, the chlorenchyma was 20% thicker but contained 11% less chlorophyll and had a lower absorptance than under the current CO2 concentration (370μmol mol−1). Greater nocturnal acidity increases and 14C accumulation following exposure to 14CO2 at night occurred at the doubled CO2 concentration despite 29–39% reductions in the activities of the two carboxylating enzymes, the lower absorptance, and a 24% increase in the cladode reflectance from 400–700 nm.