bluuebunny/crossref_metadata_2025 huggingface dataset:
ELECTROPHORETIC STUDIES OF CARPOPHORE DEVELOPMENT IN THE BASIDIOMYCETE COPRINUS CINEREUS
Authors: MOORE DAVID , JIRJIS RAIDA I.
Published: May 2006

Acrylamide gel electrophoresis was used to resolve buffer‐soluble proteins and enzymes extracted from tissues of Coprimis cinereus. The electrophoretograms of proteins of two related but compatible monokaryons differed from one another, and both differed from the electrophoretogram of the dikarvon made by crossing the monokaryons together. The electrophoretogram of the youngest carpophore primordia was markedly different from that of the dikaryon on which they were produced, and the protein spectrum of both cap and stipe altered as the tissues matured. The protein electrophoretic pattern observed in the cap was always different from that of the stipe on which the cap was borne. However, when carpophores of quite different dikaryons were compared it was found that differences between the strains were so considerable that it was not possible to identify features common to a particular tissue or structure. Variation was also found in respect of isozyme patterns even though only two quite closely related monokaryons were compared.

In the case of two enzyme activities (malate dehydrogenase and NADPH‐dehydrogenase) the monokaryons exhibited different numbers of isozymes, and in a further three (alcohol dehydrogenase, NADH‐dehydrogenase and esterase) there were clear differences in the way in which the isozyme pattern in each monokaryon related to the period of growth. The dikaryon was not associated with any predictable change in the isozyme pattern, but in all cases the dikaryon was in some way different from the parental monokaryons. Further differences were observed in carpophore tissues: in all cases the carpophore differed from its parental dikaryon. In most cases this difference was expressed as a distinctive developmental pattern of isozymes which were also detectable in mycelium; and in this the cap was often quite different from the stipe. However, for alcohol dehydrogenase and esterase, extracts of carpophore tissues possessed isozymes not detectable in extracts of mycelia.
THE DUAL POLYCLAVE: AN AID TO MORE EFFICIENT IDENTIFICATION
Authors: PAYNE R.W. , LAMACRAFT R. R. , WHITE R. P.
Published: May 2006

Polyclaves have advantages over conventional aids to identification in that the user is free to examine any convenient character. However the polyclave gives no guidance about the best character to examine next during an identification. This deficiency can be overcome by using a dual polyclave which indicates how each character separates the taxa not eliminated by characters already observed.
PHYTOPHTHORA PARASITICA INOCULATION AND INTENSITY OF VESICULAR‐ARBUSCULAR MYCORRHIZAE IN CITRUS
Authors: DAVIS R. M. , MENGE J. A.
Published: May 2006

Shoot weights, root weights, and percentages of healthy roots of mycorrhizal (Glomus fasciculatus) sweet orange inoculated with Phytophthora parasitica (20 or 50 chlamydospores g‐1 soil) were greater than those of non‐mycorrhizal seedlings at either inoculum density. However, the growth response to mycorrhizal infection was reduced 23 and 58% by inoculation with 20 and 50 chlamydospores per g soil, respectively. Mycorrhizal infection was not reduced by P. parasitica at 20 chlamydospores per g soil, but was reduced 72% in seedlings inoculated with 50 chlamydospores per g soil. The latter also reduced the phosphorus content of the leaves. Tests with seven mycorrhizal fungi on two citrus rootstocks showed that different VA infections might confer variable tolerance or resistance to P. parasitica. Two fungi, Glomus mosseae and Gigaspora margarita, not isolated from nor as nutritionally efficient as others on citrus, conferred tolerance or resistance.
ACCUMULATION OF PHYTOALEXINS IN COTYLEDONS OF FRENCH BEAN (PHASEOLUS VULGARIS L.) FOLLOWING TREATMENT WITH TRITON (T‐OCTYLPHENOL POLYETHOXYETHANOL) SURFACTANTS
Authors: HARGREAVES J. A.
Published: May 2006

Triton surfactants induced accumulation of phytoalexins in cotyledons of the French bean. The degree of accumulation was related to the phytotoxicity of the surfactant, which was dependant upon the length of the polyethoxyethanol side chain. Triton X‐35, which induced the production of large amounts of phytoalexins, killed the outer epidermal cells and two to three layers of underlying sub‐epidermal cells. Cells adjacent to these dead cells were affected but not killed by this treatment.

The main group of isoflavonoids formed were the 5‐hydroxyisoflavonoids (kievitone and licoisoflavone A). The 5‐deoxyisoflavonoids (phaseollin, phaseollidin and phaseollinisoflavan) were present only at low concentrations.

When cotyledons treated with Triton X‐35 were incubated in distilled water the major induced isoflavonoids were kievitone, which was located mainly in the cotyledons, and a compound tentatively identified as 2′,4′,5,7,‐tetrahydroxyisoflavone, which was detected in the water medium.

These results support the hypothesis that phytoalexin accumulation in the French bean is part of a wound response and involves an interaction between dead cells and their neighbouring live cells.
ULTRASTRUCTURE AND PHENOLIC HISTOCHEMISTRY OF THE CYCAS REVOLUTA‐ANABAENA SYMBIOSIS
Authors: OBUKOWICZ M. , SCHALLER M. , KENNEDY G. S.
Published: May 2006

Anabaena showed a seasonal difference in nitrogen storage when growing in Cycas revoluta coralloid roots. In winter Anabaena had numerous cyanophycin granules while in summer there were few cyanophycin granules and many degenerate algal cells. Cellular protrusions were present in the developing algal zone of coralloid roots which may facilitate metabolic exchange between the host and phycobiont. By ferric chloride ultrahistochemistry, phenolic deposits were found in the mucilaginous material of the algal zone. Phenolic deposits were also found in adjacent cells on the plasma membrane, endoplasmic reticulum, within plastids, and at the periphery of coralloid roots. The distribution of phenolic constituents could therefore provide a mechanism for excluding micro‐organisms and permitting only Anabaena to grow in cycad coralloid roots.
FACTORS CONTROLLING THE DISTRIBUTION OF TILIA CORDATA AT THE NORTHERN LIMITS OF ITS GEOGRAPHICAL RANGE III. NATURE AND CAUSES OF SEED STERILITY
Authors: PIGOTT C. D. , HUNTLEY JACQUELINE P.
Published: May 2006

Failure of regeneration of Tilia cordata in north‐west England is associated with almost complete sterility of the seeds. Between 1964 and 1979 significant numbers of fertile seeds were recorded only after the exceptionally warm summer of 1976. In contrast, large or moderate crops of fertile seed were produced at sites in central and southern England in at least 8 of these years.

Comparative studies of pollination, fertilization and seed development at sites in north‐west England, central England and northern France show relatively small differences in the proportions of flowers which are pollinated but significant differences in the rates of extension of pollen‐tubes. In samples collected in 1977 from north‐west England germinated pollen was present on most receptive stigmas but many pollen‐tubes extended only a short distance down the style and the few which reached the base appeared to be arrested in the ovary wall. In French samples pollen had germinated on all receptive stigmas and numerous pollen‐tubes had reached the ovary within 2 days of pollination.

These differences cannot be attributed to variation in the incidence of self‐pollination, as at least some trees of T. cordata in northern populations are almost certainly self‐fertile. The differences are correlated with temperatures at the time when the samples were collected. When pollen‐tubes are growing in sucrose solutions, their rate of extension shows a large response to temperature over the same range (15 to 25°C). Analysis of records shows that temperatures in north‐west England at the time of flowering are frequently too low to permit fertilization.

This is confirmed by studies of the development of ovules. Although a high proportion of ovules in T. cordata lack embryo sacs, normally at least one is functional in each ovary. In over 90% of fruit formed in north‐west England, embryos are contained in none of the 10 ovules. In less than 10% of fruit partly developed embryos are present, suggesting that temperatures are also too low in late summer to allow completion of their development.
THE ACID INVERTASES OF THE DEVELOPING THIRD LEAF OF OAT
Authors: GREENLAND A. J. , LEWIS D. H.
Published: May 2006

Changes in activities of soluble and insoluble acid invertases and in concentrations of ethanol‐soluble carbohydrates were examined during development of the third leaf of oat. The leaves did not contain any alkaline invertases. High activity of soluble invertase, high concentrations of reducing sugar and low concentrations of sucrose occurred in the non‐emerged lamina, enclosed by the sheaths of older leaves. In the developing emerged region, activity of soluble invertase rapidly declined to a steady state in the mature leaf. In this tissue, the concentration of total soluble carbohydrate was initially low but increased as the leaf matured and sucrose was always the predominant sugar. The activity of insoluble acid invertase remained relatively constant throughout leaf development. When invertase activities and amounts of soluble carbohydrates were compared in apical and basal regions of the mature leaf after ligule emergence, higher levels of both soluble and insoluble invertase, and total soluble carbohydrates, occurred in the apical half of the leaf.
ANALYSIS OF TRYPTOPHAN AND ITS METABOLITES BY REVERSE‐PHASE HIGH‐PRESSURE LIQUID CHROMATOGRAPHY
Authors: TARR JOHN B. , ARDITTI JOSEPH
Published: May 2006

Rapid separation and determination of tryptophan, N‐formylkynurenine, kynurenine, 3‐hydroxykynurenine, 3‐hydroxyanthranilic acid, nicotinic acid, nicotinamide, trigonelline, kynurenic acid and xanthurenic acid from pea seedling using reverse‐phase high‐pressure liquid chromatography is described. Accuracy of the determinations was better than 5 % and less than 50 pmol of each metabolite could be measured reliably.
THE INFLUENCE OF SOIL AERATION ON THE EFFICIENCY OF VESICULAR‐ARBUSCULAR MYCORRHIZAE I.
Authors: SAIF S. R.
Published: May 2006

Oxygen concentrations in the soil atmosphere greatly influenced the growth and mineral uptake of Eupatorium odoratum inoculated with Glomus macrocarpus. Shoot and root dry weights and length of mycorrhizal plants increased with O2 concentration up to 16%. Mycorrhizal plants at 21% O2 or non‐aerated controls were smaller than those at 12 and 16% O2. Non‐mycorrhizal plants had lower shoot and root dry wts than mycorrhizal plants at all O2 levels except at 0%. Phosphorus concentration in mycorrhizal and non‐mycorrhizal plants differed significantly but did not increase with increasing O2. Mycorrhizal plants contained higher quantities of N, K, Ca and Mg than non‐mycorrhizal and showed positive response in nutrient uptake to increase in soil O2. Inoculation and increased soil O2 resulted in higher concentrations of K and Mg but not of N and Ca. The development of Glomus macrocarpus exhibited quantitative and qualitative response to different soil O2 levels.
THE STRUCTURE OF THE SPORES OF GIGASPORA MARGARITA
Authors: SWARD R. J.
Published: May 2006

Light and electron microscopy have been used to study the emergence through the spore wall and subsequent growth and development of the germ‐tube of Gigaspora margarita. Spore‐wall penetration by the germ‐tube is unusual as two different mechanisms seem to be operating, one for the inner spore‐wall layers and another for the outer layer. As the germ‐tube develops a primary wall layer is formed, and this can be traced back to its origin as a layer continuous with the thickened region of the innermost spore‐wall layer. In the maturing germ‐tube a highly osmiophilic secondary wall is deposited and this may be the wall layer that persists when the fungus penetrates a host root and sets up a mycorrhizal association.

In common with other fungi that have been studied, the ultrastructural organization found in G. margarita can be categorized into approximately three zones: the apical zone, the subapical zone and the zone of vacuolation. Other features of the cytoplasmic organization are also discussed including the possible significance of bacteria‐like organisms, membrane‐bound crystals, osmiophilic granules and glycogen particles. Features of the culture‐grown germ‐tubes are also compared with those of host‐associated stages of the fungus reported in the literature.
DOMAINS OF ATPASE IN PLASMA MEMBRANES AND TRANSPORT THROUGH INFECTED PLANT CELLS
Authors: SPENCER‐PHILLIPS P. T. N. , GAY J. L.
Published: May 2006

Summary

The sites of ATPase at pH 7·2 and β‐glycerophosphatase at pH 5·5 and 7·2 in the presence of Mg2+ have been determined by a lead precipitation technique and electron microscopy in leaves of Pisum sativum and Phaseolus vulgaris infected, respectively, with Erysiphe pisi and Uromyces appendiculatus.

In the two plants, ATPase activity was similarly high in plasma membranes of epidermal, phloem transfer and companion cells and much lower in those of their mesophylls. The domain of the host plasma membrane invaginated around haustoria showed neither of these enzymic activities but infection did not otherwise alter their activities in either the rest of the plasma membranes of infected cells or the plasma membranes in uninfected cells. In Erysiphe pisi, the plasma membrane showed high activities with ATP and β‐glycerophosphate in haustoria but in other regions and in Uromyces appendiculatus, it lacked activity with both substrates. The sites of transition of the enzymic activities in all instances occurred at annular structures previously described in the haustorial necks.

A mechanism of solute transport into haustoria is proposed and discussed in the light of the polarized distribution of ATPase activity in infected cells.
SEED YIELDS (QUANTITY AND QUALITY) OF FIELD‐GROWN SOYBEANS EXPOSED TO SIMULATED ACIDIC RAIN
Authors: EVANS LANCE S. , LEWIN KEITH F. , CONWAY CHRISTINE A. , PATTI MITCHELL J.
Published: May 2006

Summary

Experiments were performed to determine changes in mass, protein content and carbohydrate content of seeds of soybean plants exposed to simulated acidic rain grown under standard agronomic practices and receiving ambient rainfall at Brookhaven National Laboratory during the summer of 1979. Plots were exposed three times per week to simulated rainfalls of pH 4·0, 3·1, 2·7 or 2·3 to provide inputs of 50, 397, 998 or 2506 μequiv. of hydrogen ions respectively, above ambient levels throughout the growing season. Control plots received no simulated rainfall treatments. The results indicate significant differences by both analysis of variance and two‐tailed t‐tests. These additional hydrogen ions decreased seed yields by 2·6, 6·5, 11·4 and 8·5%, respectively. A treatment‐response function was determined between the hydrogen ion concentration of the treatments and seed yield. This function, y= 21·06 – 1·01 log x, has a correlation coefficient of minus 090 and its slope is significantly different from zero. Decreased yields were attributed to a decrease in number of pods per plant since seed number per pod and mass per seed did not vary among the treatments. On a per plant basis, total seed protein decreased by 10 and 19% in plants exposed to simulated rainfalls of pH 4·0 and 3·1, respectively, compared with plants not exposed to simulated rainfalls. At these same treatment levels total non‐structural carbohydrates did not decrease significantly. The results show that additional increments of simulated acidic rain can decrease seed biomass and protein content of field‐grown soybeans.
THE POTENTIAL FOR EVOLUTION OF SALINITY TOLERANCE IN AGROSTIS STOLONIFERA L. AND AGROSTIS TENUIS SIBTH
Authors: WU LIN
Published: May 2006

Summary

Two Agrostis stolonifera L. populations, one from a sandy seashore and one from an adjacent area were found to differ in salinity tolerance. Agrostis tenuis Sibth., which grew in adjacent areas where the soil salinity was low, was not found on the shore. The potential for evolution of salinity tolerance in both A. stolonifera and A. tenuis was studied. Substantial variation in salt (NaCl) tolerance was found among natural populations in both species. Specific ion tests suggested that the lack of magnesium tolerance in A. tenuis limits the evolution of seashore ecotypes. The selection of individuals with full salinity tolerance from a non‐tolerant population in one stage of the life cycle demonstrates that the salinity tolerance in A. stolonifera could evolve rapidly.
NEW FOSSIL EVIDENCE FOR THE PAST CULTIVATION AND PROCESSING OF HEMP (CANNABIS SATIVA L.) IN EASTERN ENGLAND
Authors: BRADSHAW R. H. W. , COXON P. , GREIG J. R. A. , HALL A. R.
Published: May 2006

Summary

Fossil records of Cannabiaceae pollen and Cannabis achenes from Flandrian deposits at three sites in eastern England are presented as further evidence for the past cultivation of this crop. It is suggested that retting of hemp to extract fibre was carried out at each of the sites.
EFFECT OF WATERING REGIME ON YIELD, WATER USE AND LEAF CONDUCTANCE OF SEVEN FESTUCA SPECIES WITH CONTRASTING LEAF RIDGING
Authors: SILCOCK R. G. , WILSON D.
Published: May 2006

Summary

Seedlings of seven Festuca species with contrasting leaf surface morphology were grown in pots with three different watering regimes to simulate full irrigation, intermittent soil moisture stress or prolonged soil moisture stress.

When harvested at a similar growth stage, plants subjected to the greatest stress had the least shoot dry matter. Differences between treatments were greatest in the fastest growing plants, e.g. F. arundinacea cv. S.170. At harvest, mean transpiration rate was lowest in plants from the least stressed treatment and in species with the flattest leaf surfaces e.g. F. drymeja and F. gigantea. Whether or not allowance was made for the effect of the convolutions of the leaf surfaces in increasing effective leaf surface area, the ranking of the species for transpiration rate per unit leaf area under well watered conditions was the same.

Overall water use efficiency (WUE) was greatest in plants subjected to prolonged soil moisture stress (383 mg shoot dry matter per 100 g of water transpired) and least in those which were intermittently stressed (301 mg per 100 g). WUE was also greater for the flatter leaved species, the greatest being for F. gigantea (437 mg per 100 g) and least for F. scariosa (275 mg per 100 g). These variations in water use efficiency were not closely related to daily maximum stomatal conductance or to stomatal density of the leaves.

WUE was not highly correlated with any of the other parameters measured. At best, 46 % of the variation was associated (negatively) with the final rate of transpiration which in turn was closely correlated (positively) with the degree of adaxial leaf surface ridging.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: TEGLER B. , KERSHAW K. A.
Published: May 2006

The seasonal changes in the ability of Cladonia rangiferina to tolerate heat stress are examined in late winter, early spring and in summer. The effects of heat stress are examined as changes in net photosynthetic and respiration rates following air‐dry storage of lichen replicates at two stress temperatures, 35 and 45 °C, for 21 days. In late winter the experimental replicates show reduced net photosynthetic rates after 7 days stress treatment at 35 °C. By mid‐summer this treatment has no deleterious effects and it is concluded that there is approximately a 10 °C increase in heat tolerance in Cladonia rangiferina between late winter and mid‐summer.
EXPERIMENTAL STUDIES ON THE DISTRIBUTION OF THE SEXES OF MERCURIALIS PERENNIS L.
Authors: WADE K. M. , ARMSTRONG R. A. , WOODELL S. R. J.
Published: May 2006

(1) In a beechwood, male shoots of Mercurialis perennis were more frequent than female shoots in canopy openings, while females were more frequent at treebases than in canopy openings.

(2) Flowering shoots were more frequent than non‐flowering shoots in openings.

(3) The pH, moisture and organic content of the soil were similar at treebases and openings. The light climate was similar in both habitats in April but greater in the openings in August.

(4) Removal of canopies of Pteridium aquilinum and Rubus fruticosus, above populations of M. perennis, resulted in a greater increase in the numbers of male shoots than of female shoots.

(5) These results suggest that male and female plants differ in numbers, or growth, in different woodland microhabitats and that these differences are correlated with the above‐ground environment (e.g. light).
Experimental Studies on the Distribution of the Sexes of Mercurialis Perennis L.
Authors: WADE K. M.
Published: May 2006

(1) Transplants of Mercurialis perennis were grown under three canopy types; beech, mixed woodland and no overhead canopy (open), and in three different combinations under each canopy type; flowering males and females, flowering and non‐flowering males and females, and flowering males and females with Holcus mollis.

(2) The males grew more than the females under the open and beech canopies, while the females grew more under the mixed canopy. The growth of the sexes did not vary consistently between the three treatments.

(3) The results may explain the observed predominance of male flowering shoots in canopy openings of a woodland, but do not explain the predominance of female shoots at the treebases.

(4) Both sexes grew most with H. mollis under the canopy type where they grew most in monoculture. However, the results suggest that the differences between the growth of the sexes were increased by growing with H. mollis.

(5) An estimate of the flowering to non‐flowering shoot ratio was obtained, which showed that the ratio did not vary significantly with canopy type, suggesting that the differences in the numbers of flowering shoots of each sex at treebases and canopy openings in a woodland are not attributable to differences in the flowering to non‐flowering shoot ratio.
RESPONSES OF LEAVES OF PHASEOLUS VULGARIS L. TO SIMULATED ACIDIC RAIN
Authors: EVANS LANCE S. , CURRY THÉRÈSE M. , LEWIN KEITH F.
Published: May 2006

Relative rates of nutrient penetration, nutrient leaching, and cell permeability of first trifoliate leaves of Phaseolus vulgaris L. cv. Univ. of Idaho 111 were examined after exposure to simulated acidic rain. In buffer solutions 35SO42‐ penetrated leaves faster at pH 2·7 than at 5·7. In contrast, 86Rb+ pervaded fastest at pH 5·7, and 3H2O entered foliage at similar rates at all pH levels tested. When plants were exposed to simulated rains of various pH levels, calcium, nitrate and sulphate were preferentially leached from whole leaves by rainfalls of low pH, whereas potassium and chloride leached more at pH 5·7 and 3·4 compared with 2·7 and 2·9. Isotope tests indicated that cells within leaves were more permeable to 35SO42‐ and 3H2O and less permeable to 86Rb+ at pH 2·7 than at higher pH levels. These results suggest a wide diversity of leaf and cell permeability responses to various ions after exposure to acidic rain. In general, an increased rate of nutrient leaching at more acidic levels was correlated with a lower adaxial leaf resistance during leaf development.
OVULE DEVELOPMENT IN ORNITHOGALUM CAUDATUM (LILIACEAE) WITH A REVIEW OF SELECTED PAPERS ON ANGIOSPERM REPRODUCTION
Authors: TILTON VARIEN R.
Published: May 2006

Archesporial cell differentiation begins when ovules are four or five cells long. One parietal cell separates the archespore and nucellar epidermis. The parietal cell divides once anticlinally and its daughter cells divide once or twice periclinally resulting in four or six parietal cells. Archespore cytoplasm contains numerous small vacuoles and numerous circular, rod‐shaped bodies which stain for protein. RN A content is high. Archesporial cells increase two‐ or threefold in size and produce a megaspore mother cell which is circular in cross‐section and elliptical in longisection. Vacuoles seem to shrink slightly during the archespore/megaspore mother cell transition. Meiosis produces four megaspores separated from each other and from the nucellus by walls which stain intensely with basic fuchsin but do not fluoresce with Aniline blue. The chalazalmost megaspore typically becomes the functional megaspore while the others degenerate. Carbohydrates accumulate in the functional megaspore during the meiotic/mitotic interphase, and by metaphase, organelles, including amyloplasts, are in a perinuclear arrangement.
NATURALLY OCCURRING AUXINS AND INHIBITORS AND THEIR ROLE IN FRUIT GROWTH OF AONLA (EMBLICA OFFICINALIS GAERTN.)
Authors: RAM SANT , RAO T. RAJA
Published: May 2006

Three acidic (a1, a2 and a3) and two non‐acidic (a4 and a5) auxins were detected in the immature fruit of aonla (Emblica officinalis Gaertn.). Chromatographic studies coupled with bioassays led to the tentative identification of a2, a4 and a5 as IAA, IAAld and IAN, respectively. Two growth inhibitors (R1 and R2) were also detected in the fruit. These behaved like naringenin and abscisic acid, respectively, in paper and thin‐layer chromatography.

The inhibitors R1 and R2 were present in low concentrations in dormant fruits and did not appear to be the cause of dormancy. The factor playing a major role in the dormancy mechanism of the fruit appears to be auxin. Concentration of auxin increased in the fruit with the onset of dormancy and decreased to a low level prior to dormancy break. Shoots grew while fruits were dormant and dormancy break in fruits occurred after cessation of shoot growth. Since rise and fall in the rate of shoot growth corresponded with the period of rise and fall in the auxin content of dormant fruits and since shoot‐tips and dormant fruits contained identical auxins, it is proposed that the auxins translocated from the shoot‐tip to the fruit cause dormancy of fruits by a mechanism similar to that operative in apical dominance.
LIGHT QUALITY AND STEM GROWTH IN IMPATIENS PARVIFLORA DC.
Authors: YOUNG J. E.
Published: May 2006

Summary

Internode and hypocotyl elongation were measured in Impatiens parviflora DC. in light environments in which extra far‐red light was mixed with white light from fluorescent tubes during the photoperiod and at the end of the photoperiod. Night breaks of varying spectral composition were also given. The logarithmic rate constant of internode elongation was found to be linearly related to the estimated proportion of phytochrome existing as the far‐red absorbing form. Supplementary far‐red light at the end of the day caused no significant increase in the elongation rate whereas night break treatments significantly increased the rate of internode elongation. Hypocotyl elongation was not related to the estimated phytochrome photo‐equilibrium and appeared to be under the control of both blue and red light. The results are discussed in relation to the hypothesis that the control of stem elongation by phytochrome is an adaptation for detecting and avoiding shade.
MYCORRHIZAS OF THE LILIIFLORAE
Authors: CHILVERS M. T. , DAFT M. F. J.
Published: May 2006

Summary

Vesicular–arbuscular mycorrhizal (VAM) infections were examined in 30 cultivars of Narcissus L., Tulipa L. and Crocus L. over a period of 2 years. There was considerable diversity in the morphology of the VAM infections amongst, and variation of levels within, different genera. The possible causes of these variations, such as high levels of soluble phosphorus and host repression of the VAM endophytes, are discussed. Seven endophytes were identified from spore morphology. No apparent relationship existed between level of VAM and spore numbers in the field. Tulipa and Crocus roots were devoid of root‐hairs. Analysis of the incidence of root hairs in relation to VAM infection in Narcissus suggested that mycorrhizas were significantly less likely to bear root hairs.
ASSIMILATION OF NITROGEN IN ROOT NODULES OF ALDER (ALNUS GLUTINOSA)
Authors: BLOM JAN , ROELOFSEN WIM , AKKERMANS ANTOON D. L.
Published: May 2006

Summary

Citrulline is shown to be the predominant free amino acid in alder root nodules, while serine also occurs in relatively large amounts. Citrulline and glutamic acid are prominent free amino acids in alder xylem tissue. The activities of N2‐ase, GS, GDH, and OCT in root nodule homogenates are reported. From the Km values of GDH for NH4+ (16mM) and glutamate (0·9 mM) and the concentrations in the nodule of NH4+ (1·5 HIM) and glutamate (0·5 mM) it is concluded that GDH in alder nodules is responsible for the deamination of glutamate. The important function of GDH in the nitrogen metabolism of alder nodules is confirmed by the much higher activity of this enzyme in homogenates of nodules as compared to that in homogenates of root‐tips and leaves.

The vesicle clusters, which contain the N2‐ase activity, did not show activity of GS, GDH and OCT. The cytoplasm of the host cells was shown to possess the GS activity, while GDH and OCT probably are localized in the organelles of the host cells.
THE AZOLLA‐ANABAENA AZOLLAE RELATIONSHIP
Authors: CALVERT HARRY E. , PETERS GERALD A.
Published: May 2006

Summary

Two morphologically distinct classes of epidermal trichomes, termed simple and branched hairs, are shown to occur in Azolla caroliniana Willd. leaf cavities. The two hair types have significantly different frequencies and patterns of distribution during the development and maturation of the leaf cavities. There are only two multicellular branched hairs per cavity. These are consistently found in the same locations along the path of the foliar trace. The number of simple hairs increases rapidly during leaf development. There are about 20 simple hairs in each mature cavity and these are randomly distributed over most of the cavity wall. Clearing techniques confirmed these distributional patterns in Azolla caroliniana Willd., Azolla filiculoides Lam. and Azolla mexicana Presl. The distributional pattern was not altered by the absence of the endophytic Anabaena in Azolla caroliniana Willd. These findings are discussed in regard to the possible function of the two hair types in the Azolla–Anabaena symbiosis.
NITROGEN METABOLISM IN POTERIUM SANGUISORBA DURING WATER STRESS
Authors: TAYLOR A. A. , DE‐FELICE J. , HAVILL D. C.
Published: May 2006

Summary

Water stress, produced either by the addition of polyethylene glycol 4000 to water culture‐grown Poterium sanguisorba or by withholding water from vermiculite‐grown material, reduced nitrate reductase activity, but increased the level of glutamine synthetase in shoots, in roots the levels of all the nitrogen‐assimilating enzymes studied were reduced. In both tissues these changes were accompanied by a fall in soluble protein and water content and by an increase in the total a‐amino and proline pools. Marked changes in shoot individual amino acids were also induced by water stress, but were reversed when stress was relieved. The significance of these changes are discussed in relation to nitrogen assimilation and the mechanism of proline accumulation during drought.
THE EFFECTS OF LEAF ORIENTATION ON PHOTOSYNTHESIS, TRANSPIRATION AND DIFFUSIVE CONDUCTANCE OF LEAVES OF CONTRASTING FESTUCA SPECIES
Authors: SILCOCK R. G. , WILSON D.
Published: May 2006

Summary

A comparative study was made of the effect of leaf orientation on photosynthesis, transpiration and diffusive conductance of leaves of Festuca gigantea, F. pratensis, F. arundinacea, F. arundinacea var. atlantigena and F. marei. Conductance was also examined in F. drymeja and F. scariosa. Adaxial leaf surfaces ranged from the relatively flat (F. drymeja and F. gigantea) to the heavily corrugated (F. marei and F. scariosa). Stomatal numbers were greatest on the adaxial surface of all species, whilst the frequency on abaxial surfaces ranged from zero in F. gigantea and F. scariosa to more than 60 mm−2 in F. marei.

The photosynthesis/transpiration ratio was slightly greater with the abaxial surface uppermost and greater in those species with relatively flat adaxial surfaces. The small change in the ratio with change in leaf orientation was due to the relatively greater reduction in transpiration than in photosynthesis. Species with heavily corrugated leaves transpired faster than those with flat leaf surfaces. Change in leaf orientation did not affect the ranking of the species in terms of transpiration or of leaf conductance but, because of the contrasting responses of F. gigantea in two separate experiments, ranking was not the same. There was no consistent effect of orientation on total leaf conductance but large differences were found in the relative responses of the two surfaces in some species. In those with very few abaxial stomata the adaxial surface always had greatest conductance, whichever surface was uppermost. Where both leaf surfaces had appreciable numbers of stomata, the upper surface always exhibited the greater conductance, irrespective of whether it was the adaxial or abaxial. F. arundinacea showed the greatest change in the ratio of adaxial leaf conductance in response to change in leaf orientation.
ENZYMATIC STUDIES ON THE METABOLISM OF VESICULAR–ARBUSCULAR MYCORRHIZAS
Authors: MARX C. , DEXHEIMER J. , GIANINAZZI‐PEARSON V. , GIANINAZZI S.
Published: May 2006

Summary

The ultrastructural localization of ATPase activities was identical in onion and sycamore mycorrhizas. DES‐sensitive ATPase activity was associated with the fungal plasmalemma and paramural bodies whilst a DES‐insensitive ATPase activity was detected within the fungal vacuole. The development of the mycorrhizal fungus within root cells modified the distribution of DES‐sensitive plasmalemma‐bound ATPase activity of the host. This became concentrated around the finer arbuscule branches and appeared to be a specialization of the invaginated host membrane which occurred when arbuscule structure was favourable for nutrient exchange. These observations strengthen the hypothesis that nutrient exchange in VA mycorrhizas must occur across the living host‐fungus interface and that phosphate is transferred from fungus to host by an active transport mechanism in the finer branches of the arbuscule.
Studies ON THE TOLERANCE TO SULPHUR DIOXIDE OF GRASS POPULATIONS IN POLLUTED AREAS
Authors: AYAZLOO M. , GARSED S. G. , BELL J. N. B.
Published: May 2006

Summary

Genotypes of Lolium perenne, Festuca rubra, Dactylis glomerata and Holcus lanatus which appeared to be differentially sensitive to acute or chronic SO2 injury were compared in various morphological and physiological studies to examine some possible mechanisms of tolerance. Stomatal number and size showed no relationship with tolerance, but stomatal resistance in clean air showed a relationship with intra‐ and interspecific differences in tolerance to acute injury. Also, acute doses of SO2 increased stomatal resistance in tolerant, but not in sensitive species.

Membrane permeability was increased by acute doses of SO2, but there were no differential effects which could be related to tolerance. Uptake of 14CO2 by leaf segments in buffered solution was reduced in the presence of sulphite to a greater extent in genotypes of Lolium perenne sensitive to chronic injury. Prefumigation for 13 months with a low concentration of SO2 increased the sensitivity to sulphite, especially in the sensitive genotypes.

The species tolerant of acute SO2 injury, Dactylis glomerata and Holcus lanatus, had lower rates of 14CO2 fixation than sensitive species, and were affected less by sulphite. There were no relationships between prefumigation or sensitivity to chronic injury and the uptake or oxidation of sulphite in three Lolium perenne genotypes. Species sensitive to acute injury absorbed more 35SO2 than tolerant species. Oxidation of the absorbed radioactivity was fastest in the most tolerant and slowest in the least tolerant species.

It is concluded that many of the differential responses to acute injury can be explained by avoidance mechanisms. Some potential mechanisms of tolerance to chronic injury are discussed.
THREE FLANDRIAN POLLEN PROFILES FROM THE TEITH VALLEY, PERTHSHIRE, SCOTLAND
Authors: LOWE J. J.
Published: May 2006

Summary

Lithostratigraphies and pollen stratigraphies are described for Flandrian deposits from three infilled kettle‐holes near Callander, the Teith Valley, Perthshire. Differences between the sites, in terms of sediments and inferred hydroseral histories, are described, but broad similarities are recognized in inferred regional forest developments. The sites lie in a transitional zone between the Grampian Highlands, dominated by pine in the mid‐Flandrian, and lowland southeast Scotland, where mixed deciduous woodlands prevailed. The data presented suggest that communities dominated by birch–hazel with oak and elm encroached into the Grampians along major valleys, such as that of the River Teith. The problem of defining the role of pine in Scottish vegetational history, and the implications of an ‘Elm Decline’ recognized at one of the sites, are discussed.
NUTRITIONAL CONDITIONS REQUIRED FOR THE NON‐SYMBIOTIC CULTURE OF AN ACHLOROPHYLLOUS ORCHID GALEOLA SEP TEN TRIO N ALIS
Authors: NAKAMURA SHIN JCHI
Published: May 2006

Summary

Galeola septentrionalis Reichb. f. grew and developed roots and leaves on the agar medium containing commonly used nutrients in the absence of its symbiotic partner when kept in appropriate atmospheric conditions.

Glucose, glycerol, fructose, inositol, mannitol, mannose, ribose, sorbitol and xylose were utilized as carbon sources, arabinose, rhamnose and sorbose were not and galactose inhibited growth. Mixture of two monosaccharides in some combinations showed no synergistic effect though they had an additive effect.

An amino acid mixture and urea were good nitrogen sources, but allantoin, ammonium salt and nitrate were poor ones. Nitrite and uric acid inhibited growth.

Several vitamins did not affect growth when added to or deleted from the culture medium singly or in combinations.

Auxins improved growth immediately after germination and cytokinins showed no effect at this phase. The growth and development following this phase, however, were promoted by addition of cytokinins and not by auxins. Cytokinins given during this later phase induced rhizogenic growth at concentrations lower than 10−7 M and induced caulogenic growth at concentrations higher than 10−6 M. Gibberellin at concentrations higher than 3 × 10−7 M retarded growth.

G. septentrionalis is considered to be a prototrophic heterotroph and its mycorrhizal fungus may act by supplying commonly known nutrients to this achlorophyllous orchid.
THE DEVELOPMENT OF CHLOROPLASTS IN ROOT MERISTEMATIC TISSUE OF SECALE CEREALE L. SEEDLINGS
Authors: OLIVEIRA LUIS
Published: May 2006

Proplastids of the meristematic region of roots of rye, Secale cereale, seedlings can be induced to develop into chloroplasts after a lengthy period of continuous exposure to light. The transformation involves the formation of prolamellar bodies which eventually become the source of membrane material for the organization of granal and intergranal thylakoids. The process is also accompanied by a two‐step increase in the number of plastidial ribosomes which coincides with the extension of the intraplastidial membrane system and by a progressive accumulation of photosynthetic pigments and development of Hill reaction activity.

Overall mature chloroplasts of root meristematic tissue compare well both structurally and functionally with those from the leaves of the same plant.
THE GENETIC BASIS OF TOLERANCE TO SALT SPRAY IN POPULATIONS OF FESTUCA RUBRA L.
Authors: HUMPHREYS M. O.
Published: May 2006

Salt tolerance, determined as the percentage green leaf remaining after spray treatment, was investigated in plants from three coastal populations of Festuca rubra L. and in their hybrids with the non‐tolerant cultivar Aberystwyth S59. The most tolerant population originated from a cliff site very exposed to natural salt spray. Reciprocal differences found between progeny of tolerant and non‐tolerant maternal parents were explained on the assumption of illegitimate selfs in crosses produced by automatic cross pollination without emasculation. To allow for this, selfing parameters were introduced into a basic additive‐dominance genetic model of generation means. The potential for selfing, estimated from isolated inflorescences, was found to vary between populations. The model gave a good fit with observed generation tolerance values when selfing estimates were included and additive and dominance components of the means were calculated. In general, tolerance was dominant to non‐tolerance at salt levels similar to that of sea water but recessive at much higher salt levels, although populations differed in the degree of dominance expressed in the crosses with S59. These observations are discussed in relation to the nature and evolution of dominance of a quantitative character.
THE INFLUENCE OF NITROGEN SOURCE ON THE TOLERANCE OF HOLCUS LANATUS L.* AND BROMUS ERECTUS HUDS. TO MANGANESE
Authors: McGRATH S. P. , RORISON I. H.
Published: May 2006

Both Bromus erectus and Holcus lanatus grew better in NO3‐N than in NH4‐N. NH4‐N inhibited Mn uptake and NO3‐N enhanced it. The concentration of Mn found in both species was greater in NO3‐N than NH4‐N treated plants and increased severity of toxicity symptoms was observed in plants given NO3‐N treatments. In general, uptake and concentration of Mn was greater in Holcus than in Bromus, although Holcus displayed less severe symptoms of toxicity. Root concentrations of Mn were greater than those of shoots in Holcus. As excess Mn generally affects plant tops more severely than roots it is possible that a mechanism reducing upward translocation of Mn conferred a degree of tolerance in Holcus. Growth of the population of Holcus used was affected to a lesser extent than Bromus by large concentrations of Mn in nutrient solution which may partially account for the markedly different frequency of occurrence of these species on soils which contain high concentrations of both NH4‐N and Mn. In Bromus NH4‐N and Mn interact to reduce their combined effects but in both species the adverse effects of NH4‐N on growth for the most part masks that of Mn. Conversely with NO3‐N, itself beneficial, Mn uptake is not depressed as it is with NH4‐N and when Mn‐toxicity occurs, it is more marked. In solution culture Bromus is very sensitive to NH4‐N and also to Mn in the presence of NH4‐N or NO3‐N, whereas in the kind of habitat in which Bromus occurs N is present as NO3 and the adverse effect of any Mn present is neutralized by Ca.
A METHYLAMINE‐RESISTANT MUTANT OF THE BLUE‐GREEN ALGA, NOSTOC MUSCORUM: POSSIBLE INVOLVEMENT OF GLUTAMINE SYNTHETASE IN METHYLAMINE METABOLISM
Authors: VAISHAMPAYAN A.
Published: May 2006

Summary

Photoautotrophic growth of the Em‐R het− nif2− strain of the blue‐green alga, Nostoc muscorum, is prevented completely by 1 mM methylamine (MA) but a concentration of 2 mM MA is required to inhibit photoheterotrophic or dark heterotrophic growth. From this strain a mutant has been isolated and characterized. The mutant cannot grow photoautotrophically but its heterotrophic growth is resistant to 5 mM MA; moreover, the mutant can use MA as a carbon and nitrogen source for growth. It is suggested that because the mutant is defective in photosynthetic ability it lacks the step that is inhibited by 1 mM MA and, in the absence of such inhibition, is able to show the ability to metabolize MA by an existing enzyme system. Mutant strain Em‐RMSO‐R het+ nif+, whose growth is resistant to inhibition by l‐methionine‐dl‐sulphoximine, can grow photoautotrophically in 2 mM MA. Because this mutant is known to contain an altered glutamine synthetase, it is suggested that this enzyme may be responsible for methylamine metabolism.
OXYGEN DIFFUSION IN PEA
Authors: ARMSTRONG W. , HEALY M. T. , WEBB T.
Published: May 2006

Summary

For roots growing in anoxic media the intercellular pore‐space of the root cortex provides a channel for the diffusive flow of respiratory gases between shoot and root. Three methods were used in an attempt to quantify the diffusive resistance of this pore space (Rp) in pea. Two of the methods were based on polarographic measurements of oxygen flow through the roots: the ‘cooling’ and ‘gas‐mixture’ methods; the third was based upon measurements of porosity and root geometry (‘shape’). The last gave results which agreed closely with those obtained using gas‐mixtures. The relationship between Rp and root length followed a curvilinear form in which there was little change in Rp in the earlier stages of growth (3 to 6.5 cm). The cooling method also produced a curvilinear pattern, but numerically the resistances were considerably higher. Also, resistance rose significantly in the shorter roots. It was found that respiratory activity in the roots at 3 °C could account for these discrepancies; an electrical analogue of the root programmed for resistance (gas‐mixture/root geometry values) and 3 °C respiratory activity, gave results which matched those obtained by the cooling method. It was concluded that the gas‐filled pore space in the pea root forms a relatively non‐tortuous diffusion path and that resistance is very strongly influenced by root shape. As roots extend beyond a length of 7 cm there is an accelerated rise in Rp. An original intention, that of obtaining a measure of diffusive resistance across the root wall, was thwarted by the variability in the data.
GRAFT FORMATION IN CULTURED, EXPLANTED INTERNODES
Authors: PARKINSON M. , YEOMAN M. M.
Published: May 2006

Summary

A novel method is described in which the two halves of an explanted internode of Lycopersicon esculentum, Datura stramonium or Nicandra physaloides may be grafted together successfully in sterile culture. An absolute requirement for the formation of a successful graft is the application of indole‐3‐acetic acid (IAA at 0.2 to 2.0 mg l−1) to the apical end of the internode. The addition of kinetin (0.2 mg l−1) to the culture medium stimulated graft development but gibberellic acid (GA3 at 0−5 mg l−1) was inhibitory. The development of the graft as measured by an increase in mechanical strength and the formation of vascular connections was similar to that observed in whole plant grafts; however, fewer differentiated wound vessel members (WVMs) were detected. This technique should provide a powerful tool for the further study of graft development in compatible and incompatible combinations.
STRUCTURE AND ULTRASTRUCTURE OF PLASTIDS IN LIGHT‐AND DARK‐GROWN ZAMIA FLORIDANA DC. SEEDLING ROOTS IN VITRO
Authors: WEBB DAVID T.
Published: May 2006

Summary

In dark grown aseptic seedling cultures of Zamia floridana DC. amyloplasts with many tightly packed starch grains developed in root cortical cells. In similar cultures exposed to 12 h photoperiods of 5 klx, plastids with characteristics of chromoplasts, chloroplasts and amyloplasts were formed. Light appeared to alter the pathway of plastid development and led to the formation of chloro‐chromo‐amyloplasts in these roots.
SEASONAL CHANGES IN THE TEMPERATURE REQUIREMENTS FOR GERMINATION OF BURIED SEEDS OF APHANES ARVENSIS L.
Authors: ROBERTS H. A. , NEILSON JUNE E.
Published: May 2006

Seasonal changes in dormancy occurred in seeds of Aphanes arvensis buried in soil under field conditions. During late spring and summer the temperature range for germination extended upwards, reaching that of the surface soil in early August when emergence begins. The seeds were at their least dormant in September but the range then narrowed in autumn and winter, and dormancy was greatest in April. Exposure of seeds buried in pots of soil to high (20 to 30 °C) temperatures alleviated dormancy, while low (4 °C) temperature tended to induce it. The consistent pattern of autumn emergence appears to be determined by these cyclic changes in dormancy status which develop largely as a consequence of the temperatures experienced by the buried seeds.