bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secretory tissues in vascular plants
Authors: FAHN ABRAHAM 
Published: April 2006

SUMMARYSecretory tissues occur in most vascular plants. Some of these tissues, such as hydathodes, salt glands and nectaries, secrete unmodified or only slightly modified substances supplied directly or indirectly by the vascular tissues. Other tissues secreting, for instance, polysaccharides, proteins and lipophilic material, produce these substances in their cells. The cells of secretory tissues usually contain numerous mitochondria. The frequency of other cell organelles varies according to the material secreted. In most glandular trichomes the side wall of the lowest stalk cell is completely cutinized. This prevents the secreted material from flowing back into the plant.The salt glands in Atriplex eliminate salt into the central vacuole of the bladder cell but, in other plants, the glands secrete salt to the outside. Different views exist as to the manner in which salt is eliminated from the cytoplasm. According to some authors, the mode of elimination is an eccrine one, while others suggest the involvement of membrane‐bound vesicles.Nectar is of phloem origin. The pre‐nectar moves to the secretory cells through numerous plasmodesmata present in the nectariferous tissue. Nectar is eliminated from the secretory cells by vesicles of either KR or dictyosomal origin. In some cases, both organelles may be involved but an eccrine mode of nectar secretion has also been suggested by some authors.Carbohydrate mucilages and gums are synthesized by dictyosomes but virtually every cell compartment has been suggested as having a role on the secretion of lipophilic substances. Most commonly, plastids are implicated in the synthesis of lipophilic materials but KR may also play a part. In some cases lipophilic materials may be transported towards the plasmalemma in the KR.Resin and gum ducts of some plants develop normally or in response to external stimuli, such as microorganisms or growth substances. Among the latter, ethylene is the most effective.During the course of evolution, secretory tissues seem to have developed from secretory idioblasts scattered among the cells of the ordinary tissues. Subsequently ducts and cavities developed and finally secretory trichomes.

CONTENTS

Summary
229

I.
Introduction
230

II.
Salt glands
231

III.
Nectaries
236

IV.
Mucilages and gums
241

V.
Tissues secreting lipophilic material
242

VI.
Factors influencing the development of certain secretory tissues
246

VII.
Evolutionary considerations
248

References
250
Observations on chloroplast starch content and synthesis in the intertidal marine alga Codium fragile (Suringar) Hariot
Authors: WILLIAMS MICHAEL L. , COBB A. H. 
Published: April 2006

SUMMARYA marked seasonal response was observed in the starch content of chloroplasts of Codium fragile sampled between November 1983 and November 1984. Chloroplast starch uniformly increased throughout the life‐cycle of this alga, reaching a maximum in the summer months of approx. 5 mg glucose equivalents/109 plastids when C. fragile was in the reproductive phase. Chloroplast starch content was found to be inversely proportional to the concentration of stromal phosphate, decreasing linearly from 5 to 2 mg glucose equivalents/109 plastids over a range of stromal phosphate values of 0·75–1·5 μmol PO4/109 plastids. Similarly, the net amount of starch synthesized over 3 h by isolated chloroplasts increased linearly with respect to initial chloroplast starch content. These observations are discussed in relation to the regulation of starch synthesis by variations in the stromal P1: PGA ratio.
Ectomycorrhizal ability of genetically different homokaryotic and dikaryotic mycelia of Hebeloma cylindrosporum
Authors: DEBAUD J. C. , GAY G. , PREVOST A. , LEI J. , DEXHEIMER J. 
Published: April 2006

SUMMARYEctomycorrhizas were synthesized under axenic conditions between Pinus pinaster (Ait.) Sol. and different mycelial cultures of Hebeloma cylindrosporum Romagnesi. These included a wild dikaryon and four sib‐homokaryons (one for each mating type) belonging to the progeny of this fruiting strain.The homokaryotic mycelia formed typical ectomyeorrhizas showing a morphology and an ultrastructural organization similar to that of ectomyeorrhizas obtained with the parental dikaryon. The ultrastructural localization of acid phosphatase activities was also comparable for homokaryotic and dikaryotic mycorrhizas.These results demonstrate that the ectomycorrhizal ability is not restricted to the dikaryotic state of fungal life‐cycle since homokaryotic mycelia also formed typical and functional ectomyeorrhizas. The formation of normal mycorrhizas by homokaryotic mycelia confirms the usefulness of H. cylindrosporum as a model for genetical studies and improvement of ectomycorrhizal fungi by means of chromosomal genetics.
Localization of uricase in mycorrhizas of Ophrys lutea Cav.
Authors: BARROSO J. , CASIMIRO A. , CARRAPIÇO F. , SLOMÉ M. , PAIS S. 
Published: April 2006

SUMMARYInfected roots of Ophrys lutea present nymerous peroxisome profiles identified by diaminobenzidine (DAB) staining. The presence of uricase in these peroxisomes could also be recognized cytochemically. The activities of catalase and uricase, assayed using a crude fraction of peroxisomes, reached 0·8 μkat min−1 protein‐1 and 1·73 nakat min−1 mg protein−1 respectively. The role of uricase in purine metabolism is discussed in terms of host/endophyte interactions in O. lutea mycorrhzas.
Seasonal accumulation of mineral nutrients by kiwifruit 2. Fruit
Authors: CLARK C. J. , SMITH G. S. 
Published: April 2006

SUMMARYChanges in the concentration, distribution and quantity of macro‐ and micronutrients in the skin and flesh of fruit from 30 mature kiwifruit vines (Actinidia deliciosa var. deliciosa cv. Hayward) were recorded over a growing season in two high‐producing orchards.The concentration of copper, iron, nitrogen, phosphorus, potassium, sulphur and zinc in the flesh (seeds inclusive) declined sharply during the first 8 weeks of growth, reaching values which remained relatively constant, or declined only gradually, until harvest. For boron, calcium, magnesium and manganese flesh concentrations declined steadily throughout the season.Concentrations of nitrogen, phosphorus and potassium in the flesh were generally higher, and those of calcium manganese and zinc consistently lower, than corresponding concentrations in skin over the entire maturation period (23 weeks). Flesh concentrations of copper, iron, magnesium and sulphur exceeded those in the skin but only during the early stages of fruit development (up to 11 weeks after pollination). Boron concentrations in flesh and skin were similar during the season.The quantity of all nutrients increased throughout the season to be at a maximum by harvest The rate of accumulation of each element was greatest during the first 8 weeks of growth corresponding to the cell division phase of fruit development. There was 61–75% of the total calcium, manganese and zinc content taken up during this time, compared with 37–54% of the content of other nutrients. In the subsequent 15 weeks of development rates for nutrient accumulation declined. In the case of boron, calcium, magnesium, manganese, potassium and zinc there was minimal accumulation in the final 6 weeks prior to harvest.A mass How‐vascular transport model based on carbon and water influxes was used to predict the relative importance of phloem and xylem supply, and to partition nutrient accumulated by fruit over two time intervals; 2–8, and 8–17 weeks of growth. The model implies that where transpiration rates and phloem carbon concentrations are both high (i.e. approx. 6 ml water fruit−1 day−1 early in the season or 2 ml water mid season, and > l00 mg C ml−1), transport of nutrients occurs primarily via phloem. The only exceptions under these conditions are calcium, manganese and zinc which are translocated preferentially in xylem.
Nickel toxicity in mycorrhizal birch seedlings infected with Lactarius rufus or Scleroderma flavidum II. Uptake of nickel, calcium, magnesium phosphorus and iron
Authors: JONES MELANIE D. , HUTCHINSON THOMAS C. 
Published: April 2006

SUMMARYNon‐mycorrhizal Betula papyrifera Marsh, seedlings and seedlings infected with Lactarius rufus (Scop, ex Fr.) Fr. or Scleroderma flavidum E. & E. were treated with nutrient solutions containing 85 μM Ni or no Ni for 21 weeks. Ni was concentrated in the roots, with the highest concentrations being in the roots of plants infected with S. flavidum; Ni concentrations in stems were lowest in these seedlings. In general, Ni reduced the concentration of P, Mg, Ca, and Fe in shoot tissues. The concentration of P was correlated with that of Ni in the stems and roots. High P concentrations in the roots of S. flavidum‐infected seedlings could be correlated with potential Ni‐binding sites, allowing the Ni to be detoxified. Although Ni treatment reduced chlorophyll concentrations in L. rufus infected and uninfected seedlings, this did not appear to be related to differences in tolerance caused by the fungi.
The iron and molybdenum use efficiencies of plant growth with different energy, carbon and nitrogen sources
Authors: Raven John A. 
Published: April 2006

SUMMARYIron has many catalytic roles in photosynthesis, respiration and nitrogen assimilation; molybdenum is involved in NO3 and (usually) N2 reduction. This paper concentrates on computing the efficiency of use of Fe and Mo in growth of organisms growing with different mixtures of the major resources photons, carbon and nitrogen. This computed efficiency is defined as mol C assimilated (mol catalytic metal in the organism)‐1 s‐1. The efficiency is computed from the known in vivo involvement of Fe‐ and Mo‐containing enzymes, the specific reaction rate of these enzymes, the specific rate of these enzymes in vitro, and the growth requirements for the products of the reactions, for organisms using different energy, carbon and nitrogen sources. The predicted Fe use efficiency is greater for chemo‐organotrophic than for photolithotrophic growth with a given nitrogen source, and increases in the order N2 NO3‐ NH4+ for growth with different nitrogen sources in the presence of constant photon and carbon availability. The predicted changes with variations in nitrogen source are greater than those with variations in photon and carbon source. These predicted values may be compared with observed metal use efficiencies, defined as mol C assimilated (mol total metal in the organism)‐1 s‐1. Relatively few such observed values are available From the literature. For Fe in photolithotrophically growing microalgae the observed values can be as low as 16–17% of the predicted values, i.e. 83–84% of the Fe in the organism is not accounted for by known catalytic uses of Fe if the catalysts are operating at their maximum specific reaction rates. One possibly discordant prediction relates to the Fe and Mo cost of N2 fixation; the computations suggest that in vitro estimates of nitrogenase activity may be less than those sometimes found in vivo. The predictions also have possible implications for resource availability interactions (photons, carbon, nitrogen, Fe, Mo) in natural conditions.
Effects of nitrogen‐deprivation, and recovery from it, on the metabolism of microalgae
Authors: SYPETT P. J. , PEPLINSKA A. M. 
Published: April 2006

SUMMARYInitial rates of uptake of the ammonium analogue, [14C] methylammonium increased during N‐deprivation of the microalgae, Dunaliella primolecta Butcher, Tetraselmis subcordiformis Butcher (Wille), Chlomydomonas reinhardtii Dangeard. Amphidinium carterae Hulburt and Phaeodactylum tricornum Bohlin.The C:N ration of P. tricornutum increased from 7.4 to 19.8 during 48 h of N‐deprivation; the ability to take up [14C] methylammonium increased 50–fold during this time. Intracellular glutamate and glutamine were measured fluorimetrically; the contend of glutamate fell during N‐deprivation but that of glutamine was low and changed little. The activity of glutamine synthetase (transferase) in cells permeabilized by toluene treatment approximately doubled during the first 4 h of N‐deprivation, irrespective of whether the cells had been grown with NO2 or NH4+ as N cource: thereafter the activity of thia enzyme decreased slowly. The activity of nitrate reductase was high in NO3 grown cells and decreased during N‐deprivation. In NH4+ grown cells, nitrate reductase activity was low and increased markedly during 4 h of N‐deprivation; therefore it fell slowly.The addition of NH4+ to N‐deprived cells was followed by an immediate and large fall in the ability to take up [14C] methylammonium. In contrast, the addition of NO3 produced an initial small drop in the ability to take up [14C]methylammonium followed by another drop after 4.6 h; 8 h after NO3 addition the initial rate of [14C]methylammonium uptake was similar to that of N‐replate cells. These falls in ability to take up methylammonium were reversed when NH4+ or NO3 were removed; the reversals were not prevented by addition fo cycloheximide (an inhibitor of protein synthesis). Changes in intracellular glutamate and glutamine were followed during the periods following NO3 and NH4+ addition and removal. There was evidence fro a negative correlation between glutamine content and the rate of uptake of mehtylammonium
The physiology of basidiomycete linear organs II. Phosphate uptake by rhizomorphs of armillaria mellea
Authors: CAIRNEY J. W. G. , JENNINGS D. H. , RATCLIFFE R. G. , SOUTHON T. E. 
Published: April 2006

SUMMARYThis study shows that rhizomorphs can be produced readily in the laboratory for use in physiological and biochemical experimental. Apical and sub apical segments can be excised and treated experimentally like roots. The mean rate of phosphate uptake by apical segments as a function of phosphate concentration is very similar to that of rhizomorphs produced under more unnatural conditions. Phosphate uptake is bioasic with Km and Vmax ehemical analysis and NMR indicates that there is a sizeable amount of orthophosphate within the hyphae, located in tow pools‐cytoplasmic and vacuolar with the bulk of the orthophosphate in the vacuole. Cytochemical, electrophoretic and NMR studies show that a significant proportion of the phosphorus is in the form of polyphosphate. It would seem that initially moist of the phosphate absorbed enters the vacuole as orthophosphate and there is little direct incorporation into polyphosphate.
Inoculation of mycelial cord‐forming basidiomycetes into woodland soil and litter I. Initial establishment
Authors: DOWSON C. G. , RAYNER A. D. M. , BODDY LYNNE 
Published: April 2006

SUMMARYAlmost 1000 wood blocks, 8 cm3, of beech (Fagus sylvatica L.), colonized by the mycelial cord‐forming basidiomycetes Hypholoma fasciculare (Huds. ex Fr.) Kummer., Phallus impudius (L.) Pers., Phanerochaete (Ph.) laevis (Fr.) Erikss & Ryv., Ph. Velutina (DC ex Pers.) Parmasto, Steccherimum fimbriatum (Pers. ex Fr.) Erikss. and Tricholomopsis platyphylla (Pers. ex Fr.) Sing, were placed at the soil‐litter interface in five different woodland sites. All species except T. platyphylla grew out radially from the blocks to form a network of mycelial cords ramifying amongst the litter and upper soil horizons. Initial outgrowth was more strongly related to microclimatic factors than to availability of nutrient resources, and after 3 months significantly greater (P<S 0.05) mean radial extension had occurred from blocks implanted during spring than from those implanted in winter or mid‐autumn, Systems of H. fasciculare and Ph. Velutina were always of significantly greater (P<0.05) radius than those of the ther species after 3 and 6 months.
Interactions between ozone and plant cuticles
Authors: KERSTIENS GERHARD , LENDZIAN KLAUS J. 
Published: April 2006

SUMMARYBeech (Fagus sytvatica L.) and ivy (Hedera helix L.) plants, as well as isolated cuticles of the adaxial leaf surfaces of Citrus aurantium L., Ficus elastica Roxb. var. decora and Hedera helix L., were exposed to environmentally realistic ozone concentrations (up to 130 nl −1)in combination with acid fog (pH 3.0) for several months. Isolated Citrus, Ficus and Hedera cuticles and cuticles isolated from adaxial leaf surfaces of Hex aquifolium L. and Prunus laurocerasus L. and from fruits of Capsicum annuum L. and Lycopersicon esculentum Mill, were fumigated with 2.5 % (v/v) ozone for 1 or 2 h in dry and moist conditions, respectively. The water permeance (P) of the non‐isolated cuticles of the astomatous adaxial leaf sides of beech and ivy and of the isolated cuticles was not altered by expositure to a realistic ozone stress. Fumigation with very high ozone concentrations decreased P of isolated Ficus and Hedera cuticles by about 20% and increased P of all other isolated cuticles by up to 200% (Capsicum). In some cases the 2 h fumigation under moist conditions had no significant effect upon P. The different effects are tentatively explained in terms of the structure of the cuticles.
Synthesis in Vitro, microanalysis and 31P‐NMR study of metachromatic granules in birch mycorrhizas
Authors: GRELLIER B. , STRULLU D. G. , MARTIN F. , RENAUDIN S. 
Published: April 2006

SUMMARYThe synthesis in vitro of metachromatic granules was demonstrated in the mycelia of Paxillus involutus (Batsch) Fr. both in pure culture and associated with birch (Betula pendula Roth) roots. X‐ray microanalysis revealed the presence of phosphorus and calcium in the granules of mycorrhizas. Phosphorus‐31 NMR spectroscopy was used to identify intracellular orthophosphate and polyphosphates. In the mycelin, orthophosphate represented the major form of phosphorus accumulation, and a small pool of polyphosphate was detected in the oldest phases of culture. On the other hand, an important NMR resonance corresponding to polyphosphates was identified in the spectra of synthetic mycorrhizas. The association between a mycelium and a root seems to modify the metabolism of fungus considerably.
The role of proteins in the nitrogen nutrition of ectomycorrhizal plants
Authors: ABUZINADAH R. A. , READ D. J. 
Published: April 2006

SUMMARYPlants of Betula pendula L, were grown on a medium continuing protein as sole nitrogen source, and the ability of fungi representing a range of nutritional categories to provide them with access to protein‐N was examined by determining changes of dry weight and nitrogen accumulation with time following sequential harvests.Three fungi known to be ectomycorrhizal all gave access to the nitrogen but large differences in their effectiveness were observed, an ‘early stage’ fungus providing significantly more N than either a ‘late stage’ fungus or a facultative associate. The saprotroph Oidiodendron griseum Roback also facilitated N transfer to the plants whereas they obtained no such supply in the uninoculated condition, or when grown with an ericoid endophyte and a saprotroph isolated from the seed coat. The process of nutrient transfer from fungus to host is seen as the key rate limiting step determining growth response of the host. The physiological and ecological implications of the results are discussed.
The biology of mycorrhiza in the Ericaceae
Authors: LEAKE J. R. , READ D. J. 
Published: April 2006

SUMMARY Hymenoscyphus ericae utilizes protein as a sole source of nitrogen through the production of an extracellular proteinase. A sensitive procedure for assay of the enzyme is described and is used to determine the major characteristics of the enzyme. The enzyme has a sharp pH optimum at 2.2 with little activity above pH 5.0. Values for Km and Vmax of the enzyme were determined.Pepstatin, a specific inhibitor of carboxyl (acid) proteinases, almost completely inhibited activity, confirming that the enzyme is of this type.The characteristics of the enzyme are compared with those described for other microbial acid proteinases and the results are discussed in relation to physiological ecology both of the fungus and of its host plant.
Predicting tree frequencies from pollen frequency: an attempt to validate the R value method
Authors: SCHWARTZ MARK W. 
Published: April 2006

SUMMARYPollen‐tree correction factors are presented using regression analysis of pre‐settlement tree and pollen frequency data from 32 small lakes (1–10 ha) in Wisconsin. Regression results using vegetation samples from various sized areas around each lake for Fagus grandifolia (Ehrh.) and Tsuga canadensis (Carr.), are consistent with my initial design of using vegetation data for the single township in which a lake was found to compute the regression results. Pollen‐tree correction factors from pre‐settlement and modern data were compared for all major pollen types. Notable differences were found between pre‐settlement data and modern data sets for Wisconsin in Betula spp, T. canadensis, and Quercus spp. Little difference was observed in the fit of the regressions for these data sets. Estimations of pre‐settlement relative tree frequencies, derived from the application of modern correction factors on pre‐settlement pollen frequencies, were compared to measurements of pre‐settlement vegetation. The reconstruction of pre‐settlement vegetation was incongruous with measurements of pre‐settlement tree frequencies. It is unclear, given minor differences in the data sources for modern and pre‐settlement data, whether the observed differences in regression results are artifacts of the data sets, or reflect differences in pollen‐tree representation between the two time periods sampled. Regardless, the error associated with prediction of tree frequencies from pollen frequencies is shown here to preclude any assurance of accuracy with normal pollen count levels.
Fructan biosynthesis in excised leaves of Lolium temulentum L. III. A comparison of the in vitro properties of fructosyl transferase activities with the characteristics of in vivo fructan accumulation*
Authors: CAIRNS A. J. , WINTERS A. , POLLOCK C. J. 
Published: April 2006

SUMMARYThe induction of fructan biosynthesis in excised, illuminated leaves of Lolium temulentum L. is accompanied by a concomitant increase in extractable sucrose: sucrose fructosyl transferase (SST) activity. In leaves treated with the L‐isomer of 2‐(4,methyl‐2,6,‐dinitroanilino)‐N‐methyl propionamide (L‐MDMP) fructan biosynthesis in vivo occurs in the absence of such an increase in extractable SST. suggesting that the activity measured in vitro is not an obligatory component of fructan biosynthesis in vivo.Sucrose:sucrose fructosyl transferase preparations from L. temulentum catalyse the formation of isokestose and kestose from sucrose. The rates of synthesis of these trisaccharides were determined in the range of sucrose concentration 10‐700 mol m−3. Increase in total trisaccharide synthesis was linear with respect to substrate concentration. Isokestose was Formed over the entire range whilst kestose synthesis was inactive below 8O mol m−3. Neither isokestose nor kestose synthesis was saturated at 700 mol m −3. The Km for isokestose synthesis was high at 380 mol m−4. Conventional kinetic analysis of kestose data failed, indicating that this activity does not obey classical Michaelis‐Menten kinetics.The intracellular sucrose concentration in leaf tissue was estimated to be 100 mol m−3. At this substrate concentration, isokestose synthesis would be Functioning well below the measured Km and kestose synthesis would be operating at the extreme lower limit of its activity range.Higher oligosaccharide products of fructosyl transferase incubations were not representative of the oligofructans which accumulate in the leaf. This data casts further doubt on the physiological significance of the measured fructosyl transferase activities.Isokestose synthesis was localized in vacuoles derived from leaf mesophyll protoplasts, confirming current theories of fructan biosynthesis. However, in view of the anomalous characteristics of fructosyl transferases in vitro, we propose that unambiguous assignment of the subcellular compartmentation of fructan metabolism in leaves of Lolium temulentum should await a fuller understanding of the enzymology of fructan biosynthesis in this species.