bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pathogenesis‐related proteins in ozone‐exposed Norway spruce [Picea abies (Karst) L.]
Authors: KÄRENLAMPI SIRPA O. , AIRAKSINEN KIRSTI , MIETTINEN ANU T. E. , KOKKO HARRI I. , HOLOPAINEN JARMO K. , KÄRENLAMPI LAURI V. , KARJALAINEN REIJO O. 
Published: April 2006

SUMMARYIn a search for biochemical markers indicating the impact of ozone on plants. Pathogenesis related (PR) proteins were studied. The following observations were made: (1) PR‐proteins are present in gymnosperms, exemplified by Norway spruce (Picea abies) and (2) ozone induces PR‐proteins in Norway spruce. Studies were made by Western blot analysis using antibodies raised against seven PR‐proteins; five from tobacco (PR‐1a, ‐1b, ‐1c, ‐P and ‐Q) and two from maize (PRm 6 and 7). Each antibody recognized specific proteins in spruce needles. A more detailed study was done with the antibodies against tobacco PR‐P (endochitinase) and maize PRm 6 (β‐1,3‐glucanase). Exposure to ozone increased the contents of proteins recognized by both antibodies. In control trees, anti‐PR‐P antibody recognized a protein of about 28 kD while in the ozone‐exposed trees a form with a slightly faster migration rate in SDS‐PAGE predominated. In contrast, in the range of 34–44 kD, a family of proteins was recognized by anti‐PRm 6 antibody upon induction by ozone. In this same size range, a strong bund of 37 KD appeared in the total protein pattern, corresponding to about 5 to 10% of total protein. N‐terminal sequencing revealed a typical homology pattern shared by β‐1,3‐glucanases. This was also reflected by the enzymatic level Where ozone was shown to increase β‐1,3‐glucanase activity. By inducing pathogenesis‐related proteins, ozone may modify the response of spruce to pathogens.
Genetics of ectomycorrhizal symbiosis
Authors: ROSADO S. C. S. , KROPP B. R. , PICHÉ Y. 
Published: April 2006

SUMMARYThe interactions between genotypes of Pinus elliottii and the ectomycorrhizal fungus Pisolithus tinctorius (Pt) were investigated to assess genetic variability and heritability of root morphology and ectomycorrhizal traits. Seedlings from 15 open‐pollinated pine families, which were either uninoculated or inoculated with Pt and grown under controlled conditions in growth pouches, were analyzed for the following traits: number of shoot roots (SRN), root dry weight (RDW), shoot/root dry weight ratio (SRR), number of ectomycorrhizes (ECN), percentage ectomycorrhizal colonization (ECP) and development of extramatrical mycelium (EMD). There were significant increases in SRN and SRR in inoculated seedlings and significant family variation for RDW and SRR traits. A significant inoculation × family interaction was observed for SRN, but not for RDW and SRR. The individual narrow‐sense heritabilities for SRN, RDW and SRR were, respectively, 0·55, 1·00 and 0·68 (inoculated) and 0·43, 1·00 and 0·25 (uninoculated). The higher heritabilities for the ectomycorrhizal traits were 0·60, 0·81 and 0·53 for ECN, ECP and EMD, respectively. The higher heritabilities of root morphology traits for inoculated seedlings indicates that the mycorrhizal condition of plants should be an important factor in increasing root quality from genetic selection, especially on poor sites where the plants are more dependent on mycorrhizal. The relatively strong genetic control of ectomycorrhizal traits indicates a great potential for selecting individuals in tree breeding programs.
Photostimulation of seed germination during soil tillage
Authors: SCOPEL A.L. , BALLARE C.L. , RADOSEVICH S.R. 
Published: April 2006

SUMMARYWe conducted intensively replicated field experiments in the Willamette Valley. Oregon, USA, in order to study the role of light in triggering seed germination during soil tillage. We found that the normal practice of cultivating agricultural land during daytime can increase germination of buried seed populations between 70 and 400 above the levels recorded following nighttime cultivations. Experimental reduction of the irradiance under the tillage implements during daytime cultivation decreases the number of dicotyledonous seedlings emerged. while strong artificial illumination (>300μmol m−2 s−1; 400–800nm) of the soil surface under the implements during nighttime tillage significantly increases seedling densities. These results suggest that the enhancement of seed germination caused by daytime tillage, compared with nighttime tillage, is due to light that penetrates into the soil during the actual disturbance. The detection by the seeds of this very short exposure to sunlight requires a high photosensitivity. which provides an adaptive‘purpose’for the evolution of the very‐low‐fluence response mechanism in phytochrome‐controlled seed germination. Seedling emergence induced by nighttime control tillage was considerable in some experiments. suggesting that light perceived by seeds after cultivation or other microenvironmental factors affected by tillage may be important in triggering germination in disturbed soil.
Responses of white clover to gaseous pollutants and acid mist: implications for setting critical levels and loads
Authors: ASHENDEN T. W. , BELL S. A. , RAFAREL C. R. 
Published: April 2006

summaryWhite clover plants (Trifolium repens L. cv. ‘Grasslands Huia’) were exposed to combinations of gaseous pollutants and acid mists for 15 wk. The treatments were (a) charcoal‐filtered air (control), (b) 40 ppb SO2+ 40 ppb NO2, (e) 40 ppb Oa with additional peaks of 2 × 3 h at 80 ppb and 1 × 1 h at 110 ppb O3 and (d) SO2+NO2+O3 (a combination of treatments b and c), these being combined with acid mist treatments (6 mm wk1) with solutions at pHs of 2.5, 3.5, 4.5 and 5.6. All gaseous pollution treatments resulted in substantial reductions in plant dry weights with additive effects of SO2+ NO2 and O3 in the SO2+ NO2+O2 treatment. There was a lower dry weight, averaged over all gas pollution treatments, for plants exposed to pH 2.5 compared with pH 4.5 or pH 5.6 mists. An interactive effect of gas x mist treatments revealed that effects of acid mists on plant dry weights were overridden by the more toxic O3 and SO2+ NO2+ O3 gas exposures. Net photosynthesis was reduced in plants exposed to pH 2.5 and pH 3.5 mists compared with plants exposed to pH 5.6 mist. Rates of stomatal conductance were reduced by exposure to the gaseous pollution treatments but not to acid mists. Water loss was greater after 55 h for leaves detached from plants exposed to all gaseous pollution treatments compared with ones from control plants. There was a greater loss of water from detached leaves exposed to pH 2.5 compared with pH 5.6 mist. The quantities (loads) of S + N in gaseous form resulting in decreased growth of T. repens were calculated to be much lower than those applied in mists with no adverse effects. It is concluded that the concepts of critical levels and critical loads of pollutants need considerable refinement for realistic assessments of the threat of pollutants to vegetation.
Growth, photosynthesis and carbohydrate utilization in submerged Scirpus maritimus L. during spring growth
Authors: CLEVERING O. A. , VAN VIERSSEN W. , BLOM C. W. P. M. 
Published: April 2006

summaryThe importance of underwater photosynthesis and the use of reserve‐carbohydrates were assessed in submerged Scirpus maritimus L. during spring growth. Submerged plants were grown in outdoor ponds (90 cm deep) using different initial tuber sizes (mean 8.9 and 16.2 g f. wt) and different light treatments (0, 40, 70 and 100% of full daylight). After shoot emergence the recovery from shading and darkness was studied.The period of submerged growth lasted 9 wk. During this period the mean relative growth rate (RGR) was independently affected by shading and tuber size. At the end of this period dry weight of plants grown in darkness was only 50% of that of plants grown in full daylight or shade (70 or 40% of full daylight), whereas that of plants from small tubers was only 67% of that from large ones. As a result plants grown from small tubers in darkness had only 33% of the dry weight of those grown from large tubers in full daylight or shade.Despite these large differences in total dry weight at the end of the submerged period, shoot length remained unaffected by shading and tuber size. Shoots grown in darkness were strongly etiolated, with a slower rate of leaf appearance, but with longer leaves, than those grown in full daylight or shade. Only after emergence was shoot length as well as dry matter production greater in plants grown previously in full daylight or shade than in darkness, and greater in plants grown from large than from small tubers.During the submerged period, the relative depletion rate of reserve‐carbohydrates increased with time, but remained unaffected by shading and tuber size. The reserve‐carbohydrates were replenished after plants emergedIt was concluded that both underwater photosynthesis and tuber size had a large impact on total dry matter production in S. maritimus. They did not, however, affect the ability of S. maritimus to emerge from 90 cm deep water.
Induction of mycorrhiza‐like structures and defence reactions in dual cultures of spruce callus and ectomycorrhizal fungi
Authors: SIRRENBERG ANKE , SALZER PETER , HAGER ACHIM 
Published: April 2006

summaryHeterotrophic spruce (Picea abies [L.] Karst.) callus cells were grown in dual culture with ectomycorrhizal fungi (Amanita muscaria [L.] Pers., Lactarius deterrimus Gröger, Hebeloma crustuliniforme [Bull.] Quél., Suillus variegatus [Sw.: Fr.] O.K.) or with the pathogenic fungus Heterobasidion annosum [Fr.] Bref. Spruce cells stimulated growth of the mycorrhizal fungi, whereas growth of the pathogenic fungus was not affected. Two of the mycorrhizal fungi, 5. variegatus and L. deterrimus, caused hypersensitive reactions in spruce cells. In contact with the surface of the plant cells the mycorrhizal fungi developed densely interwoven lobed, hand‐ and fan‐shaped structures. They resembled morphological features occurring in the hyphal mantle and Hartig net of ectomycorrhizas. The ectomycorrhizal fungi did not show altered branching patterns when growing on cellophane sheets. These results demonstrate that callus cells of the host P. abies are able to stimulate fungal growth and to induce ectomycorrhizal fungi to form mycorrhiza‐like structures which normally are only generated in the presence of host roots.
Acclimation of tomato to different carbon dioxide concentrations. Relationships between biochemistry and gas exchange during leaf development
Authors: VAN OOSTEN J.‐J. , WILKINS D. , BESFORD R. T. 
Published: April 2006

summaryTomato plants were transferred to different CO2 mole fractions (350, 700, 1050 and 1400μmol CO2 mol−1) 31 d after sowing (2% of full expansion) and the light saturated rate of photosynthesis (Pmax) of the unshaded 5th leaf was measured at either an ambient CO2 mole fraction, C2 of 350 μmol CO2 mol−1 (Pmax (350)) or at the mole fraction of CO2 at which the plants were grown. At 60% nd 95% leaf expansion, Pmax of high CO2 grown plants measured at growth CO2, was greater than the Pmax (350) of the ambient CO2 grown plants. However, by leaf maturity, Pmax(growth CO2) declined linearly as growth CO2 concentration increased. Pmax (350) of plants exposed to elevated CO2 up to 60% le f expansion had not acclimated to high CO2 At 95% leaf expansion, Pmax(350) was smaller in the high CO2 grown plants. Pmax (350) w s predicted from Rubisco in vitro carboxylation capacity using tomato Rubisco kinetic constants. By 95% leaf expansion, high CO2 grown plants showed similarities to the response of plants to low nitrogen supply, in terms of Rubisco nd chlorophyll content. The observed nd theoretical relationships between the initial slopes of the Pmax/C1 responses nd Rubisco activity were statistically equivalent. Both short‐term and long‐term effects of elevated CO2 on dark respiration (Rn) were also investigated at two stages of leaf development (50 nd 100% expansion). Rn (growth CO2) was smaller for the high CO2 grown plants compared with the control plants, whereas Rn (350) was either equal or greater for the plants grown in high CO2
Regulation of assimilate partitioning in flowering plants of the monopodial orchid Aranda Noorah Alsagoff
Authors: CLIFFORD P. E. , NEO H. H. , HEW C. S. 
Published: April 2006

summaryRadiocarbon dosing of leaves and source‐sink manipulation treatments were used to clarify how assimilate partitioning is regulated in flowering plants of a monopodial Aranda orchid. The inflorescence was the dominant sink for all test leaves that were selected to determine patterns of 14C‐assimilate partitioning. Defoliation treatments had only minor effects on the distribution of 14C‐assimilate between the inflorescence and vegetative apical shoot. Excision of the inflorescence resulted in greater proportions of l4C‐assimilate being sent to all other sinks. Loss of the vegetative apical shoot had a quite different effect in that greater proportions of 14C‐assimilate were exported only to the inflorescence. Rates of 14C assimilation of remaining leaves were often raised in defoliated plants although this effect was not consistent for a single, residual leaf unless the vegetative apical shoot was also excised. Our results highlight the complexity of source‐sink relationships in indeterminate plant types showing simultaneous vegetative and reproductive growth. We suggest that inflorescence growth in monopodial orchids such as Aranda is primarily source‐limited although significant sink limitations for assimilate gain by the inflorescence exist because of a modulating effect of the vegetative apical shoot on inflorescence sink strength and the ability of source leaves to respond positively to increased sink demand.
The structure and function of the vegetative mycelium of ectomycorrhizal plants
Authors: BENDING GARY D. , READ DAVID J. 
Published: April 2006

summaryThe relationships between colonization of fermentation horizon organic matter (FHOM) by an ectomycorrhizal fungus and the activities of enzymes involved in key processes of nitrogen (N) and phosphorus (P) mobilization were investigated. FHOM was collected from a birch forest and placed in transparent observation chambers with (M) or without (NM) plants of Betula pendula Roth, the roots of which were infected by Paxillus involutus (Fr.) Fr. The fungus colonized the FHOM of the M chambers, and after different periods of occupation the activities of protease, polyphenol oxidase, peroxidase and phosphomonoesterase were determined in colonized and uncolonized substrate.Activities of protease and polyphenol oxidase increased in organic matter that had been occupied for 28–50 d, and remained elevated in FHOM that had been occupied for 50–98 d. However, although activity of phosphomonoesterase increased in FHOM that had been colonized for 28–50 d, amounts in FHOM colonized for 50–98 d decreased to below that found in uncolonized material. No difference in peroxidase activity was detected between colonized and uncolonized organic matter. The results are discussed in relation to the role of ectomycorrhizal fungi in nutrient cycling processes in temperate forest ecosystems.
Identification of ribosomal DNA polymorphisms among and within spores of the Glomales: application to studies on the genetic diversity of arbuscular mycorrhizal fungal communities
Authors: SANDERS IAN R. , ALT MONICA , GROPPE KATHLEEN , BOLLER THOMAS , WIEMKEN ANDRES 
Published: April 2006

summaryLittle information currently exists on species diversity in communities of arbuscular mycorrhizal fungi (AMF), mainly owing to difficulties in identification of field extracted spores on the basis of morphology. The possibility was explored to identify individual AMF spores from the field on the basis of a molecular marker, namely the nuclear ribosomal DNA encoding the highly conserved 5.8S rRNA with the two flanking internal transcribed spacers (ITS region), known to vary between species. A technique involving polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR–RFLP) was developed to amplify and characterize the ITS region from single AMF spores. PCR reactions with extracts from single spores of three AMF species, raised under glasshouse conditions, yielded reproducibly a single amplification product of the ITS region in sufficient amounts to allow cleavage with several restriction enzymes. The size of the ITS region, c. 600 base pairs, varied only slightly between species. Digestion of the PCR products with the restriction enzymes Hinfl and Taq I resulted in banding patterns that were reproducible for different individual spores of a given species, but showed clear differences between the three species tested. The sum of the fragment sizes was sometimes greater than the size of the original PCR product, e.g. in Glomus mosseae. Clones of the amplification product from a single spore of this fungus were obtained and sequenced. This yielded two closely related but different sequences, indicating that two different ITS regions co‐existed in the spore. The RLFP pattern of the amplification product of the spore was a result of an amalgamation of these two sequences. The technique was applied to AMF spores collected from a species‐rich grassland. Spores were sorted into morphological groups on the basis of their colour, size, and shape, and then subjected to PCR–RFLP analysis. In some morphological groups, a large percentage of spores failed to yield an amplification product, probably because they had lost their contents. A group of Glomus spores yielding amplification products in the majority of cases was further investigated: PCR RFLP analysis on 10 individual spores from the field produced 10 different patterns. Similar results were obtained with other groups of spores. The results suggest that the diversity in natural AMF communities and the genetic diversity within individual spores might he much greater than previously thought.
Sensitivity of seedlings of black cherry (Prunus serotina Ehrh.) to ozone in Great Smoky Mountains National Park
Authors: NEUFELD HOWARD S. , LEE E. HENRY , RENFRO JAMES R. , HACKER W. DAVID , YU BEN‐HUI 
Published: April 2006

summaryThe response of seedlings of black cherry (Prunus serotina Ehrh.) to ozone was evaluated in Great Smoky Mountains National Park using open‐top chambers during the growing seasons of 1989 and 1992. Two separate sets of seedlings were each exposed to various concentrations of ozone (charcoal‐filtered; 0.5 × (not used in 1989), 1.0 ×, 1.5 ×, and 2.0 × modified ambient) in two different seasons. Seasonal indices of exposure (SUM00, SUM06 and AOT40) for the 1.0 × treatments were 39.2, 1.9, and 1.62 ppm h respectively, in 1989, and 63.1, 0.9, and 0.78 ppm h, respectively, in 1992. No significant chamber effects were noted, except for reduced height growth in open plots compared with 1.0 × chambers in 1992. In both years, the 2.0 × treatment reduced total, leaf, root, and shoot‐I‐root biomass, although some of these changes were only marginally significant in 1992. Stem biomass was significantly reduced in 1989, but not 1992. Leaf area, count and weight were all highly correlated, and showed significant reductions in both years. The leaf area ratio (leaf area/total weight) was reduced in 1989, but not in 1992. Height was not affected by ozone, but diameter was reduced only in 1989. Chamber‐to‐chamber variation for biomass and leaf variates was greater in 1992, and as a result, significance levels were lower. Weibull functions were fitted to chamber means, and showed significant near‐linear declines for most components when log‐transformed data were plotted against the SUM06 and AOT40 indices. Individual Weibull models for the 1989 and 1992 data sets, and combined models over both years, were developed. Combined models were adequate for describing ozone responses for all biomass components, as determined by the likelihood ratio test. The data show‐that the two years of exposure produced similar, but not identical effects, despite large differences in initial size of the seedlings and in seasonal ozone dynamics. Leaf and root biomass were most sensitive to ozone (as determined by the slope of decrease with increasing SUM06), whereas stem biomass was least sensitive. Black cherry seedlings are shown to be among the most sensitive to elevated ozone of the 21 tree species examined to date in Great Smoky Mountains National Park.
Gametes with the somatic chromosome number: mechanisms of their formation and role in the evolution of autopolyploid plants
Authors: BRETAGNOLLE F. , THOMPSON J. D. 
Published: April 2006

summaryThe production of 2n gametes in plants, i.e. gametes with a somatic chromosome number, is considered to be the dominant process involved in the origin of polyploid plants. In this review, we provide a synthesis of current knowledge concerning the production of 2n gametes. Firstly, we describe the different methods used to detect and quantify the production of 2n gametes in plants, which include morphological and flow cytometry screening of the occurrence of 2n pollen, the analysis of crosses among diploid and tetraploid parents and the instigation of micro‐and mega‐sporogenesis. Secondly, the high level of inter‐ and infra‐specific variation in 2n gametes production is described. Thirdly, the various cytological anomalies responsible for the production of 2n gametes are reviewed, with particular reference to the relative genetic consequences of the first and second restitution divisions that give rise to 2n gametes. Fourthly, the significance of 2n gametes in crop plant improvement is discussed, in relation to somatic chromosome doubling to obtain new polyploid varieties. In particular, we compare the genetic and yield consequences of methods based on unilateral and bilateral sexual polyploidization. Finally, we outline how knowledge of the variety of mechanisms involved in 2n gamete production have increased our understanding of the evolutionary significance of polyploidy and the population biology of polyploid plants.

Contents

Summary
1

I.
Introduction
2

II.
Methods used to detect the presence and frequency of 2n gametes
3

III.
Frequency of 2n gamete production
5

IV.
Mechanisms of formation and the influence of external factors
6

V.
The genetic consequences of First Division Restitution (FDR) and Second Division Restitution (SDR)
12

VI.
2n gametes and the unilateral and bilateral sexual polyploidization of crop plants
13

VII.
The evolutionary significance of 2n gamete production
15

Acknowledgements
18

References
18
Occurrence of ectomycorrhizas on ericaceous and coniferous seedlings grown in soils from the Oregon Coast Range
Authors: SMITH JANE E. , MOLINA RANDY , PERRY DAVID A. 
Published: April 2006

summarySeedlings of Gaultheria shallon, Pseudotsuga menziesii, Rhododendron macrophyllum, and Tsuga heterophylla were grown together in the greenhouse in soils from three young managed Douglas fir forests in the Oregon Coast Range. The objective of the study was to evaluate the ability of ericaceous plants and overstory conifers to share compatible mycorrhizal fungi in order to assess potential mycorrhizal linkages. Ericoid mycorrhizal fungi were examined in Gaultheria and Rhododendron to assess their assumed presence in soils of the Pacific Northwestern region of the United States. Nine ectomycorrhizal types were recognized on the conifers and two on the Ericaceae. All nine ectomycorrhizal types occurred on both conifer species, and the two ectomycorrhizal types on the ericaceous hosts resembled types associated with the conifer hosts. Ectomycorrhizal fungi occurred on all the conifer seedlings and in trace amounts on 26% of the ericaceous seedlings in the study. Ericoid mycorrhiza developed on all the ericaceous seedlings.