bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between hyphal and arbuscular colonization and sporulation in a mycorrhiza of Paspalum notatum Flugge
Authors: DOUDS DAVID D. 
Published: April 2006

summaryExperiments were conducted to determine correlation between sporulation by an arbuscular mycorrhizal (AM) fungus to proliferation of arbuscules or intercellular hyphae. Paspalum notatum Flugge seedlings were inoculated with the AM fungus Gigaspora margarita Becker & Hall and treated with either tap water, nutrient solution without P, or nutrient solution with P to manipulate colonization levels. Plants receiving the nutrient solution without P tended to have greater colonization than plants receiving water only (e.g. 62 vs 54%, respectively at week 7) but lesser percentage root length with arbuscules (e.g. 27 vs 38% respectively at week 7). Mycorrhizas receiving the nutrient solution without P sporulated sooner (week 7) than the water only treatment and had larger spore populations (e.g. 20.9 vs 14.2 spores cm−3 at week 13). Nutrient solution with P did not completely inhibit colonization, and though these plants had total colonized root lengths similar to those of the water treatment, spore populations were much less (2.9 cm−3 at week 13), Spore populations correlated equally well with total root length as with root length colonized and root length with arbuscules in the water and nutrient solution without P treatments. Populations were not correlated to these measures for the nutrient solution with P, indicating that the host may have limited the ability of a unit length of colonization to produce spores in this treatment.
Uptake and translocation of prey‐derived 15N and 32P in Utricularia vulgaris L.
Authors: FRIDAY LAURIE , QUARMBY CHRIS 
Published: April 2006

summaryThe rootless submerged carnivorous hydrophyte Utricularia vulgaris L. is a potentially useful subject for the quantitative study of foliar nutrient uptake and use, because known quantities of nutrients can be supplied precisely to individual leaves. We report here results obtained by hand‐feeding prey labelled with 15N and 32P to leaves of known age in plants growing in near‐natural conditions.Prey‐derived 15N was rapidly taken up and translocated: in plants fed via 3‐d‐old leaves, about 30% of the prey 1SN appeared in the immature parts of the plant within 2 d. Almost all parts of the plant that were immature at the time of feeding received and retained prey 15N throughout the 20 d experiment. Some backward translocation of 1SN was observed, but only up to the second day after feeding. 32P was also taken up and translocated rapidly, but was not retained by young tissues after they had become mature. Backward translocation of 32P was observed into side‐shoot meristems and flowers arising on parts of the plant older than the fed leaves. This is in contrast to 15N uptake, where side‐shoot buds and flowers received labelled nitrogen only if they arose on parts of the plant younger than the fed leaves.
Reproductive biology of eight sympatric Myrtaceae from Central Brazil
Authors: PROENÇA CAROLYN E. B. , GIBBS PETER E. 
Published: April 2006

summaryEight species of Brazilian Myrtaceae were studied for their flowering phenology, pollination biology, breeding system and fruiting success: Eugenia dysenteries, Siphoneugena densiflora, Blepharocalyx salicifolius, Campomanesia pubeacens, C. velutina, Myrcia linearifolia, M. rhodosepala and Psidium firmum. Flowering strategies were mass‐flowering and steady‐state types, with two species showing a pulsed flowering. All species were bee‐pollinated with pollen as the floral reward; flowers opened early in the morning and lasted one day; buzz‐pollination was registered in three species. Pollinator‐sharing of Bombus spp. bees occurred in the four savanna shrubs, pre‐dawn pollination by Ptiluglossa sp. (Colletidae) was found in arboreal 5. densiflora and the remaining two trees had open pollination systems. The three forest species were markedly self‐incompatible, and two of the savanna species were effectively so, whilst three savanna species showed self‐compatibility.
Characteristics of secretion of nectar in Pyrostegia venusta (Ker‐Gawl.) Miers (Bignoniaceae)
Authors: GALETTO L. , BERNARDELLO L. M. , JULIANI H. R. 
Published: April 2006

summarySecretion patterns and characteristics of nectar of an Argentinian population of Pyrostegia venusta at different times of the day are described with respect to flower age. Flowers are protandrous and hummingbird‐pollinated, producing exudate before and after anthesis. There is a concomitant increase in both concentration and volume in 1‐d‐old flowers, followed by a sharp increase in concentration and decrease in nectar volume in 2‐d‐old flowers.Removal of nectar throughout the flower lifetime increases the volume produced but reduces the concentration. Flowers with nectar removed three times produced 73% more nectar volume than the controls, and those with nectar removed twice produced 20% more. However, the total mass of sugar produced was comparable in all three sets.Two experiments were designed to determine the effect of changes in volume and concentration on nectar production: (a) the concentration was initially maintained while the volume was changed (halved, doubled and untouched as a control), and (b) the concentration was reduced to a minimum replacing nectar by different volumes of distilled water as in the previous experiment. These concentration‐volume changes do not essentially affect total nectar production irrespective of treatment. A powerful homeostatic mechanism would operate by which the plant maintains both these variables in the nectar. The differences observed in the nectar production rate among treatments would indicate its existence.
Use of 15N labelling and 15N natural abundance to quantify the role of mycorrhizas in N uptake by plants: importance of seed N and of changes in the 15N labelling of available N
Authors: HÖGBERG PETER , NÄSHOLM TORGNY , HÖGBOM LARS , STÅHL LENA 
Published: April 2006

summary 15N labelling and variations in natural 15N abundance offer possibilities to quantify the importance of mycorrhizas in plant N uptake. When atom %15N or 15N natural abundance of mycorrhizal and non‐mycorrhizal plants are compared in experiments, one, however, has to account for dilution effects of seed N and the interaction between changes in sslabelling of the available pool and N uptake. This has been considered in studies of N2 by diazotrophs, but has not been explicitly corrected for in studies of N uptake by mycorrhizal plants. An example is given, where ectomycorrhizal plants obtained an atom %15N different (P < 0.01) from that of non‐mycorrhizal plants, but where this could be ascribed to dilution effects of seed N and differences in N uptake rates interacting with changes in 15N labelling, rather than to variations in use of N sources or to isotope fractionation during uptake. Careful N and l5N budgets based on seed N and sequential harvests, as well as frequent measurements of atom % or abundance of 15N in available pools of N, are thus necessary in studies of this kind. Regressions of 15N on total N are a useful alternative to comparisons of means of atom % only.
The influence of IAA, carbohydrate and mineral concentration in host tissue on ectomycorrhizal development on Pinus sylvestris L. in relation to nutrient supply
Authors: WALLANDER B HÅKAN , NYLUND JAN‐ERIK , SUNDBERG BJÖRN 
Published: April 2006

summaryConcentrations of indole‐3‐acetie acid (IAA) in lateral roots, fungal biomasa (ergosterol) in lateral roots and extrametrical mycelium, and carbohydrates and minerals in shoots were measured in mycorrhizal and non‐mycorrhizal Pinus sylvestris L. seedlings supplied with different amounts of N and P. IAA concentrations in lateral roots of mycorrhizal seedlings were the same or lower than those in control seedlings. The concentrations of IAA in mycorrhizal root tips of Laccaria bicolor inoculated seedlings were 40% lower than those in lateral roots. IAA concentrations in lateral roots of L. color‐inoculated seedlings were positively related to X supply. A rise in N supply reduced the development of extramatrical mycelium of L. bicolor and the fungal biomass in lateral roots of Hebeloma crustuliniforme‐inoculated seedlings. High N supply reduced concentrations of starch, Ca and Mg in shoots but increased those of glucose and fructose. P had no effect on fungal growth or on concentrations of IAA. Fungal growth was negatively correlated with levels of soluble carbohydrates in shoots, shoot concentrations of N, P and K, relative growth rate and the shoot: root ratio of the seedlings. Starch, Mg and Ca concentrations in the shoot were positively correlated with fungal growth. No support was found for the hypothesis that IAA is important in regulating mycorrhizal colonization.
Ectomycorrhizas and rhizosphere microorganisms of seedlings of Pseudotsuga menziesii (Mirb.) Franco planted on a degraded site and inoculated with forest soils pretreated with selective biocides
Authors: COLINAS C. , MOLINA R. , TRAPPE J. , PERRY D. 
Published: April 2006

summaryInoculation of planting holes with small amounts of soil from a mature forest or a plantation can improve formation of ectomycorrhizas on Pseudotsuga mensiesii (Mirb.) Franco seedlings in degraded eleareuts in southwestern Oregon. To determine the component (s) of transferred soil responsible for increased ectomycorrhiza formation, we treated soil from a clearcut, a mature forest, and a plantation with one of the following: fertilizer to test for the effect of nutrients, dimethoate and carbufuran to test for the effect on microarthropods or nematodes, fumagillin to test for the effect on protozoa, captan to test for the effect on fungi, penicillin and oxytetracycline to test for the effect on bacteria, pasteurization to test for the effect of active forms of organisms. Tyndallization to test for the effect of resting forms of organisms, or water as a control. We studied the effect of inoculation with soil subjected to these treatments on number and types of ectomycorrhizas, and length of active mycelium, and number of active bacteria in the rhizosphere. Inoculation with untreated forest or plantation soils increased the number of ectomyeorrhizas but did not change the mycorrhizal types present. Most agents had different effects in different soils, inoculation with pasteurized and Tvndallized clearcut and plantation soils increased the number of Rhizopagon‐ and Thelephora‐type ectomyeorrhizas and decreased the number of active bacteria, as did untreated forest soil. We hypothesize that the role of the soil transfer is to provide a rhizosphere environment free from a deleterious organism present in the clearcut. In this environment, beneficial organisms present in the clearcut or brought in with the seedling from the nursery can proliferate.
Wound‐induced hydraulic signals and stimulus transmission in Mimosa pudica L
Authors: MALONE M. 
Published: April 2006

summaryThe mechanism of wound signalling in Mimosa is discussed with a brief historical survey. It is demonstrated that strong wound‐induced hydraulic signals occur in Mimosa pudica L., as in many other plants, and that the basipetal mass flows associated with these events could disperse solutes from the wound site at rates of at least 15 mm s−1 and possibly up to 300 mms−1. When such wound‐induced ‘hydraulic dispersal’ is taken into account, Ricca's theory of chemical signalling can explain long‐distance transmission in Mimosa. The pattern of long‐distance wound signalling in Mimosa is shown to be consistent with such a model.Implications for theories of electrical signalling in Mimosa are discussed and it is concluded, in agreement with some previous workers, that systemic wound‐induced electrical phenomena in Mimosa are not travelling signals, but are local responses to the travelling chemical messengers.
Storage and secretion processes in the spore of Gigaspora margarita Becker &Hall as revealed by high‐pressure freezing and freeze substitution
Authors: BONFANTE PAOLA , BALESTRINI RAFFAELLA , MEND GEN KURT 
Published: April 2006

summarySpores of Gigaspora margarita Becker &Hall, an arbuscular mycorrhizal fungus, were cryofixed using high‐pressure freezing and prepared for Transmission electron microscopy by freeze substitution. The cryotechniques improved the ultrastructural preservation of the Spore cytoplasm and revealed storage and secretion processes in the germinating sports of G. margarita. The storage structures in the hydrated and /or germinating spores have been identified as belonging to three different classes: (i) lipid droplets limited by 3 membrane, (ii) protein‐like bodies inside specialized vacuoles., and (ii) glycogen particles. During germ‐tube differentiation, an abundant membranous system was observed. It consists of rough KR. tubules and balloon‐like Golgi equivalents, which produce vesicles associated with electron‐dense granules. The granules seem to be incorporated into the wall. The results suggest that secretion and Storage occur in the fungal spore during events comparable to those in yeasts or plant cells.
Effects of soil phosphorus on spore germination and hyphal growth of arbuscular mycorrhizal fungi
Authors: DE MIRANDA J. C. C. , HARRIS P. J. 
Published: April 2006

summaryThe direct effects Of soil phosphorus on sport germination and hyphal growth of the arbuscular mycorrhizal fungi (AM), Glomus etunicatum Beck &Beck &Gerd., E3 and Scutellospora heterogama (Nicol &Gerd) Walker &Sanders, were investigated by means of two soil‐agar plate experiments. In the first experiment, the percentage spore germination and hyphal length of G. etunicatum, measured at ten different P levels and three periods of incubation, were affected by the P status of the soil. The best correslation with P level in the soil occurred at 7 d of incubation for spore germination and at 14 d far hyphal growth and hyphal growth increment. Spore germination was stimulated when 12.5 μ PO g−1 was applied to the soil and decreased with further soil P increments. Hyphal growth decreased significantly with soil P amendments above 37.5 μg P g−1 In the second experiment including three different P levels and the three AM endophytes, soil P affected spore germination and hyphal growth, and both decreased at the high phosphate treatment for G. etunicatum and S. heterogama. The K3 spare germination was similar to the other two species, but the hyphal growth was poorer. S. heterogama was more sensitive to P fertilization than the Glomus spp. and for the three species the hyphal production was not proportional to spore size.
Allocation of 14C‐carbon in ectomycorrhizal willow
Authors: DURALL D. M. , JONES MELANIE D. , TINKER P. B. 
Published: April 2006

summaryThe flow of carbon from plant to fungus in ectomycorrhizal associations has not been well quantified. The objective of this study was to use 14C to quantify the increase in fixed carbon translocated below ground in ectomycorrhizal relative to non‐mycorrhizal willow (Salix viminalis L, Bowles hybrid). Rooted cuttings were inoculated with Thelephora terrestris (Ehrh). Fr. or left non‐mycorrhizal. Non‐mycorrhizal plants were grown at the same (4 mg kg−l bicarbonate‐extractable P) (NM‐P) or at a higher (21 mg kg−1) soil P concentration (NM +P), one at which the non‐mycorrhizal plants were similar in size to the mycorrhizal (M‐P) plants. At 41, 51, 76 and 89 days after planting, the shoots were exposed to a pulse of 14CO2. Plants were harvested after a 202 h chase period. The 14Cactivity was quantified in live fractions: shoot tissue, shoot respiration, ‘root’ tissue (= roots plus fungi), ‘root’ respiration (= CO2 released below ground) and soil. Of the total 14C detected in these five fractions, M‐P plants allocated from 3.9% (harvest 1) to 11.5% (harvest 4) more to the below‐ground fractions (‘root’ tissue, soil and ‘root’ respiration), than did the NM‐P plants. Differences between NM+P and M‐P plants were only half of those above (3.1 % and 4.4% at harvests 2 and 3, respectively, compared to 6.4 % and 7.4%, respectively for the difference between NM‐P and M‐P). Correction for differences in root/shoot ratio between M‐P and NM‐P plants eliminated the observed differences in carbon distribution only at the first three harvests. There was no evidence for increased ‘root’ respiration fates or rhizodeposition being responsible for the increased carbon diverted below ground by M‐P plants.
Carbon use efficiency in mycorrhizas theory and sample calculations
Authors: TINKER P. B. , DURALL D. M. , JONES M. D. 
Published: April 2006

summaryThe benefit to a fungus by a mycorrhizal association is that it gains carbon from its host. A benefit to a host is usually a nutritional one, but any resulting increase in dry weight may be counteracted by the carbon consumed by the fungus. The carbon costs of mycorrhizal fungi have been calculated using 14C pulse‐chase experiments in the laboratory or by estimating turnover rates in the field. Both of these techniques have their limitations, but estimates have been remarkably consistent amongst most laboratory studies. Carbon demands of the fungus may not reduce theoretical growth enhancement in plants which are sink‐limited but would be expected to do so iii source‐limited plants. A model of carbon use efficiency is developed based on the economic concepts of cost and benefit. Efficiency is defined in terms of carbon gained via the growth response to infection, and the carbon expended supporting the fungus. Practical considerations of measuring carbon allocation, and calculating carbon use efficiency are discussed. In an experiment on Salix viminalis L., colonized by Thelephora terrestris (Ehrh.) Fr., the carbon use efficiency calculated by this method was on overage 85% based on shoot tissue production, and 95% based on whole plant production.
Reproductive responses to mycorrhizal colonization of Abutilon theophrasti Medic, plants grown for two generations in the field
Authors: SHUMWAY DURLAND L. , KOIDE ROGER T. 
Published: April 2006

summaryPlants of Abutilo theophrasti Medic, were grown for two consecutive years in the field. First generation (maternal) plants were grown either with or without mycorrhizal inoculation with Glomus intraradices Schenck & Smith. We collected early and late cohorts of seeds which were used to product second generation (offspring) plants. Offspring plants were grown either with or without mycorrhizal inoculation with G. intraradices. Irrespective of maternal mycorrhizal status, we found that offspring of early cohort seeds had greater percent mycorrhizal colonization early in the growing season, a greater proportion of plants flowering early in the season, and a greater number of capsules per plant at the end of the season compared with offspring of late cohort seeds. These differences were observed despite the fact that shoot N and P concentrations were greater in offspring of late cohort seeds. We found that mycorrhizal colonization of maternal plants decreased the average time to reproductive maturity in offspring plants, but did not significantly influence any other vegetative or reproductive trait in the offspring plants. Mycorrhizal colonization of offspring plants resulted in a greater number of branches per plant and a greater number of mature capsules per branch. Mycorrhizal colonization of offspring plants also resulted in a significant increase in seed P content, bur only for seeds that were produced late in the growing season, We conclude that mycorrhizal colonization of the offspring generation was more important than mycorrhizal colonization of the maternal generation m determining offspring reproductive output, but maternal seed cohort is an important interacting factor that influences offspring fecundity.
Effects of nitrogen supply on the source of nitrogen used for regrowth of laminae after defoliation of four grass species
Authors: THORNTON B. , MILLARD P. , DUFF E. I. 
Published: April 2006

summaryPlants of Agrostis castellana, Festuca rubra, Lolium perenne and Poa trivials were grown in sand culture and supplied with a complete nutrient solution containing either 0.5 or 1.5 mol m−3 NH4NO3. Plants were clipped weekly to a height of 4 cm. At the time of the ninth clipping (day Q) the nutrient solution was replaced by one in which all nitrogen (N) was enriched with 15N to 5 atom %, but otherwise identical. Weekly destructive harvests were taken from day 0 to day 35. whilst unharvested plants continued to receive the weekly clipping. The 15N‐labelling allowed discrimination between remobilization within the plant from current root uptake in supplying N for laminae regrowth. For all four species a poor N supply reduced both N uptake by roots and the potential N available for remobilization, as welt as allocation of both these sources to laminae regrowth. Overall the N supply derived from root uptake was reduced by a greater extent, and the proportion of N in laminae regrowth derived from remobilization increased with low N supply. The rate of remobilization of the N which was accessible was slower with a reduced supply of N. The species order for increasing proportion of N for laminae regrowth being derived from remobilization was L. perenne < P. trivialis < A. castellana < F. rubra irrespective of N supply.
Growth and assimilation of NH4+ and NO3− by Paxillus involutus in association with Betula pendula and Picea abies as affected by substrate pH*
Authors: EK H. , ANDERSSON S. , ARNEBRANT K. , SÖDERSTRÖM B. 
Published: April 2006

summaryThe influence of pH on the growth and assimilation of 15N‐labelled ammonium and nitrate was studied in intact ectomycorrhizal systems consisting of Betula pendula Roth and Picea abies (L.) Karst. colonized with a common mycelium of Paxillus involutus (Batsch) Fr. The plants were grown together in Plexiglass observation chambers containing non‐sterile peat with three different pH values, 4.11, 5.1 and 6.1. The mycorrhizal mycelium was allowed to prow over a barrier into an area of peat from which plant roots Here excluded. Labelled 15NH4NOa was supplied, either as 13NH4NO3 or as NH415NO2, exclusively to the fungal mycelium. Shoots and roots were analyzed for 15N in total nitrogen while the mycelium was analyzed for 15N in NH41, NO3− and free amino acids. The 15N labelling pattern indicated that ammonium was immediately assimilated into amino acids, primarily glutamine, by the fungal mycelium at the uptake site. The amino acids were then translocated to the mycorrhizal roots. In contrast, nitrate‐N was not assimilated in the mycelium but rather transferred to the mycorrhizal roots as nitrate. Mycelial uptake and transfer of N to the spruce and birch seedlings were significantly higher for NH4‐N than for NH4‐N. No firm conclusions about pH effects on the preferential uptake of ammonium and nitrate could he drawn. However, pH had a pronounced effect on the mycelial growth of P. involutus which was hampered severely at pH 6.1 and to a lesser extent at pH 5.1.