bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stay‐green genotypes of Phaseolus vulgaris L.: chloroplast proteins and chlorophyll catabolites during foliar senescence
Authors: BACHMANN ANDRÉ , FERNÁNDEZ‐LÓPEZ JOSE , GINSBURG SAMUEL , THOMAS HOWARD , BOUWKAMP JOHN C. , SOLOMOS THEOPHANES , MATILE PHILIPPE 
Published: April 2006

SUMMARYLeaf senescence was analyzed in stay‐green mutants of Phaseolus vulgaris. Impaired yellowing in these genotypes was accompanied by abnormal retention of thylakoid membrane proteins including the light‐harvesting chlorophyll‐binding protein of photosystem II, the 33 kDa polypeptide of the oxygen‐evolving complex, cytochrome f and the psaF protein of photosystem I. On the other hand, ribulose bisphosphate carboxylase was somewhat more labile in the mutant than the wild‐type. The stay‐green character was not associated with unusual persistence of chlorophyll biosynthesis enzymes. During senescence, normal leaf tissue accumulated an array of fluorescent (FCC) and non‐fluorescent (NCC) compounds with chromatographic and spectrophotometric properties similar to those of chlorophyll catabolites previously identified in other species. With the exception of one prominent NCC and a trace of one FCC, these constituents were absent from extracts of stay‐green genotypes, strongly supporting the proposal that they are indeed products of chlorophyll breakdown. The kinetics of their accumulation during senescence was consistent with a primary or intermediary role for FCCs in the catabolic pathway whereas NCCs seem to be final products. The complement of FCCs and NCCs in Phaseolus vulgaris was as distinct from that of the previously‐studied species barley and rape as the latter are from each other. Genotypic and interspecific variations in the biochemistry of senescence are discussed in relation to genetic regulation of the process.
Extra‐ and intra‐cellular carbonic anhydrase in relation to culture age in a high‐calcifying strain of Emiliania huxleyi Lohmann
Authors: NIMER N. A. , GUAN Q. , MERRETT M. J. 
Published: April 2006

SUMMARYThe relationships between extra‐ and intra‐cellular carbonic anhydrase, calcification rate, utilization of dissolved inorganic carbon (DIG) and culture age were investigated in a high‐calcifying strain of Emiliania huxleyi. The detection of carbonic anhydrasc was dependent on culture age; neither the extra‐cellular activity of intact cells nor activity in crude homogenates was detected until the stationary phase. By the stationary phase DIC in the medium was totally depleted and the calcification rate had decreased by 60°0. Extra‐ and intra‐cellular carbonic anhydrase was stimulated by Na+but not Cl ions. The isolation of intact organelles by isopycnic gradient centrifugal ion from exponential and stationary phase cultures of high calcifying cells showed high carbonic anhydrase activity in the chloroplast fraction but carbonic anhydrase was not detected in low‐calcifying cells even after gradient centrifugation. Although 50/IM ethoxyzolamide was an effective inhibitor of carbonic anhydrase activity in vitro, photosynthetic 14CO2 fixation was only inhibited 30%, calcification rate 10%, and the internal inorganic carbon pool unaffected in intact cells. It is proposed that chloroplast carbonic anhydrase maintains the steady state flux of COj, from the chloroplast envelope to Rubisco, much of the CO2 arising by release from HCO3−in the cytosol, required to maintain cytoplasmic pH near neutrality in high‐calcifying cells.
Does ozone stress change the primary or secondary metabolites of birch (Betula pendula Roth.)?
Authors: LAVOLA A. , JULKUNEN‐TIITTO R. , PÄÄKKÖNEN E. 
Published: April 2006

SUMMARYIn field experiments three clones of two‐year‐old birch (Betula pendula Roth.) were exposed for one growing season to an ozone concentration 1–2 times higher than ambient. At the end of August, leaf and stem material was analyzed for a wide range of primary and secondary metabolites. Although most of these metabolites were not significantly affected by ozone exposure, ozone‐treated leaves contained larger concentrations of total sugars and reduced amounts of the phenolic glucoside, dehydrosalidroside. In the stems, greater amounts of catechin pentoside, hyperoside and papyriferic acid were found. The results indicated considerable inter‐ and intra‐clonal variation in the production of phytochemicals in both leaves and stems.
Reconstitution of the symbiosis of Gunnera manicata Linden: cyanobacterial specificity
Authors: JOHANSSON CHRISTINA , BERGMAN BIRGITTA 
Published: April 2006

SUMMARYThe ability of various cyanobacteria to establish a symbiosis with Gunnera manicata Linden was examined under sterile conditions. Cyanobacterial strains were classified as infective if they could be found in a well‐defined infected area within the Gunnera gland tissue 40 d after inoculation. Nine out of 17 tested Nostoc strains were able to infect G. manicata. The infecting strains were all symbiotic isolates. These included six out of ten isolates from Gunnera spp., the isolate from the cycad Macrozamia sp., that from the hornwort Anthocerns sp., and that from the lichen Peltigera canina. None of the seven strains belonging to genera other than Nostne was capable of infection, even though the majority of them were also able to form motile hormogonia. Negative staining revealed fimbria‐like structures in both infective and non‐infective strains. In fact, two of the non‐infecting strains had the most abundant fimbria‐like filaments. No conspicuous structural or ultrastructural differences between infecting and non‐infecting strains were detected using light‐ and transmission electron microscopy. We conclude that selection between conceivable microsymbionts is exerted at the recognition and/or entrance stage.
Biology of the ectomycorrhizal genus, Rhizopogon
Authors: MOLINA RANDY , TRAPPE JAMES M. 
Published: April 2006

SUMMARYTwenty nine isolates of Rhizopogon from 20 spp. differed markedly in their ability to form ectomycorrhizas with Douglas fir, western hemlock and lodgepole pine in pure‐culture syntheses, Within the four sections of Rhizopogon there were similarities in ectomycorrhizal appearance and range of potential hosts. Intermediate and overlapping ectomycorrhiza! characters were evident in closely related species complexes. Although the host‐specificity of many species, based on field observations of sporocarps, often correlated with their host range in the syntheses, some fungi formed well‐developed ectomycorrhiza on hosts with which they appear not to be associated in the field. The specificity of host associations is suggested as a major contributor to the speciation and diversification of Rhtzopogon in the Pacific Northwest of the USA and Canada.
Plant species that can be linked by VA mycorrhizal fungi
Authors: NEWMAN E. I. , DEVOY C. L. N. , EASEN N. J. , FOWLES K. J. 
Published: April 2006

SUMMARYPairs of plant species were grown in soil in transparent plastic containers, one grass with one dicotyledonous species. All the species are normally VA mycorrhizal. Hyphal links were observed between eight of the species‐pairs. However, in only three of these pairs was internal VA mycorrhizal infection clearly seen in both species. These involved a grass plus a legume, and grasses with the woody climber Hedera helix.
Secondary metabolites in plant defence mechanisms
Authors: BENNETT RICHARD N. , WALLSGROVE ROGER M. 
Published: April 2006

SUMMARYMany secondary metabolites found in plants have a role in defence against herbivores, pests and pathogens. In this review, a few examples are described and discussed, and some of the problems in determining the precise role(s) of such metabolites highlighted. The role of secondary metabolites in defence may involve deterrence/anti‐feedant activity, toxicity or acting as precursors to physical defence systems. Many specialist herbivores and pathogens do not merely circumvent the deterrent or toxic effects of secondary metabolites but actually utilize these compounds as either host recognition cues or nutrients (or both). This is true of both cyanogenic glucosides and glucosinolates, which art discussed in detail as examples of defensive compounds. Their biochemistry is compared and contrasted. An enormous variety of secondary metabolites are derived from shikimic acid or aromatic amino acids, many of which have important roles in defence mechanisms. Several classes of secondary products are ‘induced’ by infection, wounding or herbivory, and examples of these are given. Genetic variation in the speed and extent of such induction may account, at least in part, for the difference between resistant and susceptible varieties. Both salicylates and jasmonates have been implicated as signals in such responses and in many other physiological processes, though their prescise roles and interactions in signalling and development are not fully understood.

Contents

Summary
617

I.
Introduction
617

II.
Cyanogenic glucosides
618

III.
Glucosinolates
619

IV.
Non‐protein amino acids
621

V.
Alkaloids
622

VI.
Plant phenoiics
623

VII.
Plant terpenes, sesquiterpenoids and sterols
626

VIII.
Phytoalexins
626

IX.
Salicylic acid and methyl jasnionate
627

X.
Conclusions
628

References
629
Effects of atmospheric ammonia and ammonium sulphate on vesicular–arbuscular mycorrhizal colonization in three heathland species
Authors: HEIJNE B. , DUECK A. , VAN DER EERDEN L. J. , HEIL G. W. 
Published: April 2006

SUMMARYThree heathland species. Arnica montana L., Viola canina L. and Nardus stricta L., were exposed to gaseous ammonia and artificial rain containing ammonium sulphate for 11 wk. Plants infected with Glomus fasciculatum (Thaxter Sensu Gerdemann) Gerd & Trappe grew faster than non‐mycorrhizal plants. Ammonia increased the shoot dry weight of both mycorrhizal and non‐mycorrhizal V. Canina and mycorrhizal N. stricta. Only mycorrhizal V. canina and non‐mycorrhizal N. stricta grew faster when supplied with increasing concentrations of ammonium sulphate. The nitrogen tissue concentration, in all three species, was not influenced by vesicular–arbuscular mycorrhiza (VAM), but increased when plants Wete treated with ammonia. Mycorrhizal and non‐mycorrhizal N. stricta and mycorrhizal V. canina had a higher N tissue concentration when supplied with ammonium sulphate. The phosphorus tissue concentration was higher when plants were infected VAM, but tended to be lower in the presence of ammonia or ammonium sulphate. Mycorrhizal plants had higher total amounts of N and P than non‐mycorrhizal plants and plants treated with ammonia had higher total amounts of N than non‐treated plants. VAM colonization increased in all three species when treated with ammonia but was not affected by exposure to ammonium sulphate. Mycorrhiza decreased the sensitivity of N. stricta to drought, while ammonia decreased the sensitivity to drought for all three species. The effects of additional nitrogen in relation to N/P ratios are discussed with respect to the ecological consequences for these heathland species.
Morphological changes and photosynthate allocation in ageingHebeloma crustuliniforme(Bull.) Quel. andLaccaria bicolor(Maire) Orton mycorrhizas ofPinus ponderosaDougl. ex. Laws
Authors: DURALL D. M. , MARSHALL J. D. , JONES MELANJE D. , CRAWFORD R. , TRAPPE J. M. 
Published: April 2006

SUMMARYSeedlings ofPinus PonderosaDougl, ex. Laws were grown in root observation containers. They were inoculated with eitherHebeloma crustuliniforme(Bull.) Quel. orLaccaria bicolor(Maire) Orton or left uninoculated (control). Oil a monthly basis starting at the eighth month of a 12‐month growing period, roots (mycorrhizal root tips from inoculated plants, non‐mycorrhizal from control plants) were traced onto acetate sheets. Each root tip was classified as light, ‘intermediate’ or ‘dark’ in colour. Roots initiated between months eight and nine were monitored for the next 90 d. All root tips progressed from light‐brown to dark‐brown to black for all three treatments.Hebeloma crustuliniforme, and to a lesser extentL. bicolor, retarded this progression relative to the control. At the end of 12 months, seedlings were labelled with14CO2to determine the effects of ectomycorrhizal inoculation on carbon supply to roots of the different morphological categories. The amount of14C in ‘light’L. bicolorandH. crustuliniformemycorrhizas was 2.3 and 1.8 times greater, respectively, than that in ‘light’ control root tips. The amount of14C in mycorrhizas of the inoculated treatments and, to a lesser extent, roots of the control seedlings decreased as they progressed from ‘light’ to ‘dark’. It is concluded that pondersa pine seedlings continue to allocate photosynthate to morphologically older roots, perhaps to meet maintenance requirements or to supply carbon for growth and metabolism of extra‐matrical hyphae. Such allocation may enhance root longevity, which would have an important influence on tree, forest and soil carbon budgets.
Decomposition of 14C‐labelled substrates by ectomycorrhizal fungi in association with Douglas fir
Authors: DURALL D. M. , TODD A. W. , TRAPPE J. M. 
Published: April 2006

SUMMARYEctomycorrhizas of Pseudotsuga menziesii (Mirb.) Franco were synthesized in pure culture with Cenococcum geophilum Fr., Laccaria bicolor (Maire) Orton, Rhizopogon vinicolor Smith, or Suillus lakei (Murr.) Smith and Thiers. The mycorrhizal plants were grown in sterile vessels with peat/vermiculite plus 14C labelled hemicellulose, cellulose, Douglas fir needles, or humic polymers as an organic substrate. The sum of the 14C respired and that found in the seedling after 240 d of growth was used to quantify decomposition of the labelled substrates. All mycobionts released at least 20–30% of the 14C in hemicellulose and all were able to release 14C from cellulose and needles, escept L. buolttr, which failed to release 14C from needles. S. lakei released the largest amount of 14C from cellulose. C. geophilum, S. lakei and R. filticolor released similar amounts of 14C from needles. Generally, substrates could be ranked in terms of ease of breakdown by the ectomycorrhizal fungi as follows: humic polymers < needles < cellulose < hemicellulose.
Variation in mycorrhizal development and growth stimulation by 20 Pisolithus isolates inoculated on to Eucalyptus grandis W. Hill ex Maiden
Authors: BURGESS T. , DELL B. , MALAJCZUK N. 
Published: April 2006

SUMMARYTwenty isolates of Pisolithus, covering u range of hosts, basidiocarp types and geographic locations were compared on their ability to form mycorrhiza in vitro with Eucalyptus grandis and to stimulate seedling growth in vivo. There was a large variation between isolates in the rate of mycorrhizal development and this was used to categorize isolates into six types. Mycorrhiza of seedlings inoculated with type I isolates were the most advanced with a dual‐layered mantle, a fully‐developed Harris net and radially elongated epidermal cells. Mycorrhiza of seedlings inoculated with types II V isolates were progressively less advanced so that mycorrhiza of type V isolates had a thin single‐layered mantle, the Hartig net was only partially developed and the epidermal cells were not elongated. Root lips of seedlings inoculated with type‐ VI isolates were non‐mycorrhizal. Inoculated seedlings were transplanted directly into undrained pots containing a yellow sand deficient in phosphorus. Growth stimulation of E. grandis seedlings in the glasshouse varied greatly between Pisolithus isolates, with dry weight increases ranging from two to 45 times that of the non‐inoculated control seedlings. Extent of mycorrhizal development was positively correlated to growth stimulation in the glasshouse and it is proposed that this could be used as an indicator of isolate aggressiveness and consequently the potential of an isolate to promote tree growth.
O3‐induced degradation of Rubisco protein and loss of Rubisco mRNA in relation to leaf age in Solanum tuberosum L.
Authors: ECKARDT N. A. , PELL E. J. 
Published: April 2006

SUMMARYThe effect of ozone (O3) on Rubisco degradation was investigated by dark incubation of potato plants (Solanum tuberosum L. cv. Norland) following exposure to charcoal‐filtered air or 0.30μl l−1 O3 for 6 h. Rubisco small subunit (rbcS) mRNA levels declined dramatically in control foliage within 10.16 h of dark incubation; thus declines in Rubisco protein following a 48‐h dark period were ascribed to proteolytic degradation. Foliage sampled from the 4th and 6th leaves from the apex, designated immature and mature, respectively, showed no effect of O3 on Rubisco protein content immediately following the exposure. However, the decline in Rubisco quantity during the dark incubation was significantly enhanced by prior treatment with O3 in the mature leaves. The immature leaves sustained a similar decline in Rubisco quantity in both O2 and control treatments. O3 had a significant effect on the relative quantity of rbcS mRNA in the immature leaves (sampled immediately following the O3 exposure). Levels of rbcS mRNA in mature leaves and Rubisco large subunit (rbcL) mRNA in both leaf ages were not significantly affected by O3, There was no effect of O3, on Rubisco quantity in immature or mature leave's of plants maintained in the greenhouse under a 16 h photoperiod far 48 h following the exposure. Thus the effect of short‐term O3 exposure on processes affecting Rubisco synthesis and degradation may have been transient, and a more prolonged exposure would he necessary to effect a decline in Rubisco protein quantity in plants grown under a 16 h photoperiod. We concluded that O3 caused enhanced degradation of Rubisco in mature leaves of plants induced to senesce by dark incubation following O3 exposures. The potential for O3‐induced reduction in synthesis of Rubisco also exists.
Cytokinins in the xylem sap of the dioecious fynbos shrub, Leucadendron rubrum Burm. f.: seasonal fluctuations and their possible interaction with morphological characteristics as expressed in the two sexes
Authors: DE KOCK MARIANNA , THERON KAREN I. , SWART PIETER , WEILER ELMAR W. , BELLSTEDT DIRK U. 
Published: April 2006

SUMMARYBrandies of male and female plants of the dioecious Leucadendron rubrum Burm. f. were collected on the site of the Weikamp weather‐station in the Jonkershoek State Forest, Stellenbosch, from July 1990 to September 1991. Xylem sap was extracted from the branches by vacuum extraction. HPLC was employed to purify the xylem sap and to separate the cytokinins prior to quantitation by ELISA. The cytokinin levels in the purified plant samples were determined using rabbit antiserum‐based ELISAs for the determination of the levels of the cytokinins DHZR and IPA, and a trans‐ZR specific monoclonal antibody‐based ELISA for the determination of the levels of the cytokinin ZR.It was observed that the levels of the cytokinins DHZR and ZR did not differ significantly between male and female plants but did correlate with the seasonal growth patterns. The levels of the cytokinin IPA, in male and female plants of L. rubrum, not only correlated specifically with the different seasonal growth patterns observed but differed significantly between male and female plants. Peaks in the levels of all three cytokinins. i.e. ZR, DHZR and IPA, occurred during the study period. These peaks corresponded with the phenological development of L. rubrum, specifically with vegetative bud break and inflorescence differentiation and appeared to be synchronized with the growth and development.An attempt was also made to correlate cytokinin levels with the extreme differences in morphological characters exhibited by male and female plants, and possibly to explain to what extent these phytohormones influence sex expression in L. rubrum
Developmental anatomy of internal cavities of epidermal origin in leaves of Polygonum (Polygonaceae)
Authors: CURTIS J. D. , LERSTEN N. R. 
Published: April 2006

SUMMARYTwo types of internal oil cavity that develop from the epidermis occur in leaves of 15 species of Polygonum, sect. Persicaria. In one type, found in 10 species, epidermal cells develop directly into epidermal/epithelial (E/E) cells. In P. hydropiper, a single protoderm cell enlarges, grows into the mesophyll, and divides only anticlinically to form three, to seven (usually four) E/E cells. The enlarging E/E cells separate along the medial pan of their shared walls to form a central cavity. The protoplast of each E/E cell then retracts from the inner cell wall and deposits a new cell wall to form a peripheral lacuna between the original inner wall and the new wall. The original cell walls between central cavity and peripheral lacunae eventually disappear leaving an oil‐filled mature internal cavity but with each E/E tell tip still exposed at the surface. The second type, found m five species, involves both subepidermal and epidermal cells. In our examples. P. glabrum and P. densiflorum, the initial protoderm cell divides anticlinally to form 8–20 cells, most of which grow into the mesophyll, divide periclinally, and separate to become epithelial cells surrounding a cavity. The Outermost cells remain epidermal the deeper ones are secondarily subepidermal. Peripheral lacunae and a central cavity form as in the epidermal cavity, but they do not merge into a single mature cavity. Epithelial cells, peripheral lacunae, and central cavity collectively form a subepidermal cavity complex.
Stems of Allium cepa L. contain starch
Authors: ERNST M. , BUFLER G. 
Published: April 2006

summaryStems of Allium cepa L. were prepared for histochemical analysis and stained by periodic acid‐Schiff reaction and Lugol's iodine for detecting starch grains (amyloplasts). Starch was found in the root cap of the root initials, around the central cylinder vascular tissues of the stem and in the primary thickening meristem during sprouting but not during dormancy.
High soil carbon dioxide concentrations inhibit root respiration of Douglas fir
Authors: QI JINGEN , MARSHALL JOHN D. , MATTSON KIM G. 
Published: April 2006

summaryTotal and basal respiration (RtandRb, respectively) of intact and undisturbed roots of one‐year‐old Douglas fir seedlings,Pseudotsuga menziesiivar.glauca[Beissn] Franco, were measured at experimentally varied soil carbon dioxide concentrations ([CO2]). Use of specially designed root boxes and a CO2gas‐flow compensating system designed around an infrared gas analyzer (IRGA) allowed controlled delivery of CO2to roots and simultaneous measurements of CO2released by roots. Root respiration rate responded to each inlet [CO2], independent of whether the previous concentration had been higher or lower, within two to three hours (pairedttest = 0.041,P= 0.622, andn= 13). Total and basal respiration rates decreased exponentially as soil [CO2] rose from 130 ppm, well below atmospheric [CO2], to 7015 ppm, a concentration not uncommon in field soils. Analyses of variance (ANOVA) showed that the effects of soil [CO2] on rates of total and basal root respiration were statistically significant. Root respiration rates decreased by 4 to 5 nmol CO2g−1dry weight of roots s−1for every doubling of [CO2] according to the following equations: ln(R1) (nmol CO2g−1s−1) = 5.24–0.30*ln[CO2] withr= 0.78,P< 0.0001, andn= 70; and ln(Rb) (nmol CO2g−1s−1) = 6.29–0.52 * ln[CO2] withr= 0.82,P< 0.0001, andn= 35. The sensitivity of root respiration to [CO2] suggests that some previous laboratory measurements of root respiration at atmospheric [CO2], which is 3 to 10‐fold lower than [CO2] in field soils, overestimated root respiration in the field. Further, the potential importance of soil [CO2] indicates that it should be accounted for in models of below‐ground carbon budgets.