bluuebunny/crossref_metadata_2025 huggingface dataset:
THE COMBINED EFFECTS OF LOW TEMPERATURE AND SO2+NO2 POLLUTION ON THE NEW SEASON'S GROWTH AND WATER RELATIONS OF PICEA SITCHENSIS
Authors: FREER‐SMITH P. H. , MANSFIELD T. A.
Published: April 2006

Picea sitchensis (Bong.) Carr. seedlings were exposed to SO2, NO2 and SO2+ NO2 during dormancy in controlled environments, and were taken to night temperatures of 4, 0, −5, −10 and −15 °C in a freezer. Conditions in the freezer were carefully monitored during the low–temperature treatments. In two experiments, different photoenvironments and temperature regimes were imposed prior to the cold treatments, and different effects were observed. In the first, only limited frost hardiness was achieved and night temperatures of −15 °C were lethal. Temperatures of −5 and − 10 °C led to poor survival of lateral buds, particularly in plants exposed to 45 ppb SO2. The poor bud break in plants exposed to SO2 and to − 5 °C resulted in a loss of the effectiveness of this temperature as a chill requirement. Pressure‐volume analysis showed that the shoots of plants exposed to NO2 had greater elasticity (lower elastic moduli, e), so that loss of turgor occurred at lower relative water contents. In contrast, a hardening period (2 weeks in night/day temperatures of 3/10 °C and 8 h days at 50 μmol m−2 s−1 PAR) gave decreased elasticity and lower solute potentials of spruce shoots. In the second experiment, exposure to 30 ppb SO2 and SO2+ NO2 led to slight, but consistent, increases in frost injury to the needles of plants frozen to − 5 and − 10 °C. The results suggest that the main interaction of low temperatures and winter pollutants may be on bud survival rather than on needle damage, but that effects are subtle, only occurring with certain combinations of pollutant dose and cold treatment.
LEAF MICROMORPHOLOGY OF SEA CLIFF AND INLAND PLANTS OF AGROSTIS STOLONIFERA L. DACTYLIS GLOMERATA L. AND HOLCUS LANATUS L.
Authors: MCNEILLY T. , ASHRAF M. , VELTKAMP C.
Published: April 2006

Scanning electron microscope examination of the morphology of adaxial and abaxial leaf surfaces of salt spray‐tolerant and normal plants of Agrostis stolonifera L., Dactylis glomerata L. and Holcus lanatus L. was carried out. Differences were found in degree and types of waxiness of epidermal cells, number and size of macro‐hairs and prickles, epidermal cell lengths and extent to which stomata were sunken. These differences were consistent with a reduction of the wettability, and hence salt spray damage, to adaxial leaf surfaces. Abaxial leaf surface differences were much less pronounced.
ENVIRONMENTAL CONTROL OF THE SEASONAL GROWTH OF THE SUBMERSED AQUATIC MACROPHYTE LOBELIA DORTMANNA L.
Authors: FARMER ANDREW M. , SPENCE DAVID H. N.
Published: April 2006

Leaf growth, photosynthesis and soluble carbohydrate content were measured for Lobelia dortmanna L. across one year in a small oligotrophic lochan in the northwest of Scotland at a number of sites, varying in degree of exposure, sediment type, nutrient concentrations and plant form. Leaf production and loss occurred during the entire year, although production and photosynthesis were maximal in the early summer. Soluble carbohydrate was highest in the early spring, and was lowest when leaf production was greatest. Environmental changes (solar irradiance, lochan temperature and water levels) were also related to growth rates, showing a particularly strong correlation between irradiance and the relative leaf growth rate. Little influence of epiphytes or limitation of growth by nutrient or the contribution of inorganic carbon was found.
SPORNE'S ADVANCEMENT INDEX REVISITED
Authors: CHAMPMAN J. L.
Published: April 2006

A new method of measuring differences between dicotyledonous families – the ‘evolutionary distance’ (ED) – is proposed. This aims to complement Sporne's ‘advancement index’ of correlated characters. The EDs of families from the Chloranthaceae and Magnoliaceae are used to predict which families may have been in existence the longest. As the Hamamelidaceae and Saxifragaceae appear to be most ancient by this method, the EDs from the Hamamelidaceae have been calculated to test this. From these EDs, other ancient or core families can be proposed. Most notable are the Sphaerosepalaceae, Buxaceae, Canellaceae, Cunoniaceae, Euphorbiaceae, Rosaceae and Tetracentraceae. By considering the ED and advancement index together, the Quiinaceae, Dipentodontaceae and Trochodendraceae can be added to this list.
COMPARATIVE ABILITIES OF LEAF SURFACES TO NEUTRALIZE ACIDIC RAINDROPS
Authors: ADAMS C. M. , HUTCHINSON T. C.
Published: April 2006

A study was made of the ability of leaf surfaces of sunflower, radish, cabbage and sugar beet to neutralize acid rains (pH 30) of varying duration. Sprayings with simulated rain of 5, 15, 45 and 90 min duration were made weekly. The species were selected for their contrasting leaf surfaces (e.g. wettability, droplet retention, hairiness and thickness of epicuticular waxes). Following acidic sprays, the pH of raindrops on leaves was measured at intervals until drops dried. Leaves of cabbage and sugar beet, which had smaller areas of contact with raindrops than those of radish and sunflower, were markedly less able to neutralize acidic droplets. Droplets on the cotyledons of all species had higher pHs than droplets on the true leaves. Differences in age of true leaves, however, did not significantly affect droplet pH. The duration of rain spraying had a significant effect on leaf surface neutralization. In 2‐ and 3‐week‐old plants, long exposures to rain (i.e. 45 and 90 min) markedly increased neutralization in comparison with short exposures. In 6‐week‐old plants, the effect was the reverse; sprays of 45 and 90 min significantly decreased foliar neutralization compared with sprays of 5 and 15 min. Significant decreases in both leaf and root dry weights were found for cabbage and sugar beet treated with rain of pH 30 for 45 and 90 min, compared with both unsprayed plants and those treated with the same pH for shorter periods. Radish showed a similar but non‐significant trend.

Chemical analysis of raindrops (initially pH 3–0) left on foliage for 75 min showed an increase in the concentrations of Ca2+, Mg2+ and K+, sometimes up to 50‐fold. The elemental composition of drying droplets collected on 4‐week‐old plants was not affected by the duration of previous rain exposures. In contrast, the Ca2+ and Mg2+ concentrations of drying droplets on 7‐week‐old plants exposed to 45 and 90 min rains were significantly lower than on those exposed to 5 and 15 min rains. Drying droplets differed sharply in their cation concentrations in different species. There was, however, a poor correlation between the degree of droplet neutralization and its acquired cation status. Results from a subsequent experiment using cabbage, radish, broccoli, brussel sprout and tomato, in which droplet pHs were measured over acid rain‐induced lesions and over uninjured leaf tissue, showed significantly higher pHs in the droplets over the foliar lesions.
DEPRESSED METABOLIC ACTIVITY OF VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI AFTER FUNGICIDE APPLICATIONS
Authors: KOUGH J. L. , GIANINAZZI‐PEARSON V. , GIANINAZZI S.
Published: April 2006

Summary

Application to soil of either benomyl or captan significantly decreased the growth of vesicular‐arbuscular mycorrhizal (VAM) onion (Allium cepa L. cv. Hyper) plants 4 weeks after treatment but non‐VAM plants were not affected. Fungal colonization of the onion roots, as indicated by non‐vital staining with chlorozole black E, was depressed 2 weeks after fungicide application. However, decreases in metabolically active VAM fungal tissue, revealed by a succinate dehydrogenase assay, could be detected as soon as 3 d after fungicide treatment. There was little difference between the fungicides in their effect on the VAM fungi used. The usefulness of the succinate dehydrogenase assay in predicting effects of fungicide is discussed.
COLONIZATION OF WESTERN WHEATGRASS (AGROPYRON SMITHII RYDB.) BY VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI DURING THE REVEGETATION OF A SURFACE MINE
Authors: LOREE M. A. J. , WILLIAMS S. E.
Published: April 2006

Summary

Development of vesicular‐arbuscular mycorrhizas and proliferation of roots of western wheat‐grass (Agropyron smithii Rydb.) were investigated in a revegetated mine soil in southeastern Wyoming, USA. Total rooting density (root length per volume of soil) and spore frequency increased as a function of age of the reclamation (time elapsed since reseeding). Topsoil replaced during reclamation was apparently the primary source of mycorrhizal inoculum in the most recently reclaimed site. Seedlings growing on spoil material without topsoil were generally non‐mycorrhizal, but mycorrhizal rooting density was not significantly correlated with the residual content of soil organic matter (an indicator of the proportion of topsoil in the growth media). Mycorrhizal colonization in sites up to three years old was minimal in spite of rapid increases in overall rooting density. Mean rooting density, mean degree of infection, and mean spore frequencies in older sites (five to seven years) were comparable to those of an adjacent undisturbed rangeland, but were highly variable. Mature, non‐mycorrhizal specimens were observed, suggesting that A. smithii is not highly dependent on mycorrhizal infection for survival on this disturbed site.
THE DISTRIBUTION OF MYCORRHIZAS AMONG FAMILIES OF VASCULAR PLANTS
Authors: NEWMAN E. I. , REDDELL P.
Published: April 2006

Summary

From a literature search, information has been compiled on the mycorrhizal status under field conditions of 20 or more species in each of 25 families. The percentage of species which are mycorrhizal ranged from 100% in seven families to 8% in Cruciferae, many families having additional species that are sometimes mycorrhizal. No family in the list was consistently non‐mycorrhizal. Apart from the Ericaceae, the families were either predominantly ectomycorrhizal or predominantly VA mycorrhizal. However, almost all families had at least one example of each of these mycorrhizal types.
EFFECTS OF PRUNING ON THE BRANCHING HABIT OF MORUS ALBA L. AND THE ABSCISSION OF THE APICES OF THE SHORT SHOOTS
Authors: SUZUKI TAKEO , KOHNO KIYOSHI
Published: April 2006

Summary

The formation of long shoots and short shoots, growing out from erect one‐year‐old stems sprouted from six‐year‐old pruned stumps of mulberry (Morus alba L. cv. Shin‐ichinose), has been studied. In contrast to the branches of the unpruned trees showing an acrotonic growth habit, where only several terminal buds elongate, the buds of these stems, including the basal buds, burst simultaneously in the spring. A few upper shoots continued to elongate until autumn, forming long shoots, whilst the other shoots (lateral shoots) formed short shoots, the apices of which abscinded until early June. Excision of the long shoots before abscission of the apices of the short shoots took place resulted in continued growth of the short shoots and formation of long shoots in the upper portion of the pruned stem. The results suggest that the dominance of the upper shoots (long shoots) is maintained by a correlative control system acting between the apices of long shoots and short shoots.
THE PROBLEM OF VARIABILITY IN STOMATAL RESPONSES, PARTICULARLY APERTURE VARIANCE, TO ENVIRONMENTAL AND EXPERIMENTAL CONDITIONS
Authors: SPENCE RICHARD D.
Published: April 2006

Summary

The extreme variability observed in stomatal responses to identical treatments has hindered the drawing of specific conclusions about how stomata respond to environmental factors and the mechanisms that drive these responses. This review considers stomatal aperture as a characteristic response and the ramifications of the observed within‐sample variance in aperture. In the wake of past research efforts, the efficacy of experimental techniques developed to observe stomatal aperture is reviewed, environmental, morphological and physiological factors that are thought to contribute to aperture variance are discussed, and the desirability of implementing procedures to reduce aperture variance is assessed. By taking into account these considerations, researchers may be better able to plan their future efforts.
EFFECTS OF SALINITY AND NITROGEN ON GROWTH AND WATER RELATIONS IN THE MANGROVE, AVICENNIA MARINA (FORSK.) VIERH.
Authors: NAIDOO G.
Published: April 2006

Summary

Young plants of Avicennia marina (Forsk.) Vierh, were subjected to a factorial experiment with three concentrations of NaCl (0.1, 0.3, 0.5 M) and three of NH4C1 (0.14, 1.4, 14 mg N I−1) in solution culture for three months.

Nitrogen and salinity had significant effects on dry matter accumulation in shoots and roots. In general, growth of shoots and roots was significantly greater at 0.1 M NaCl than at 0.3 and 0.5 M NaCl. Added nitrogen at 14 mg N I−1significantly increased shoot growth at 0.1 and 0.3 M NaCl. In roots, differences were significant at 0.3 M NaCl and 14 mg N I−1. Nitrogen had no significant effect on shoot or root growth at 0.5 M NaCl. At lower salinities there was greater allocation of resources to shoots at 14 mg NI−1.

Increasing salinity decreased stomatal conductance, tissue water potentials and the concentrations of nitrogen and potassium in tissues. Nitrogen levels had no effect on tissue water potentials. These results are discussed in relation to the effects of salinity and nitrogen on productivity, nutrient uptake and on plant water relations.
EVIDENCE FOR INTERGENERIC TRANSFORMATION IN FILAMENTOUS, DIAZOTROPHIC CYANOBACTERIA
Authors: SINGH D. T. , BAGCHI S. N. , MODI D. R. , SINGH H. N.
Published: April 2006

Summary

A clonal population of a mutant Nostoc muscorum, with the ability to assimilate azide as a fixed nitrogen source, was used as a source of donor DNA for transforming Anabaena doliolum from an azide‐sensitive to an azide‐assimilating phenotype. The donor DNA. transformed A. doliolum efficiently and the transformation process was sensitive to DNAase, resistant to RNAase A, dependent on photosynthetic light and required a specific contact period between donor DNA and recipient cells. The gene(s) responsible for azide assimilation appear to be located on chromosomal DNA and not on plasmid DNA. The transformants of A. doliolum resemble the azide assimilating mutant strain of N. muscorum in respect of (1) azide repression of heterocyst and nitrogenase formation, (2) azide‐dependent increase in phycocyanin to chlorophyll ratio. These results suggest that the chromosomal DNA of mutant N. muscorum, and not its plasmid DNA, is the carrier of genetic information for its azide assimilatory phenotype and that this can be transferred efficiently to A. doliolum.
BIOMETRIC ANALYSIS OF MODERN AND LATE PLEISTOCENE CONES OF PICEA FROM WESTERN CANADA
Authors: WARNER BARRY G. , CHMIELEWSKI JERRY G.
Published: April 2006

Summary

Late Pleistocene and early Holocene fossil Picea cones and modern cones of Picea sitchensis (Bong.) Carr. from Cape Ball, Queen Charlotte Islands, British Columbia were compared for morphological variability. Modern cones of P. sitchensis from Cape Ball are most similar to populations in the area of Prince Rupert, British Columbia. The fossil cones resemble most closely modern P. glauca (Moench) Voss. and allopatric P. sitchensis × P. glauca in cone size, scale size and phyllotaxy, which suggests introgression between P. sitchensis and P. glauca in late Pleistocene time on the north coast of British Columbia. These results suggest that P. glauca and P. sitchensis migrated northward shortly after deglaciation along the coast and that P. sitchensis maintained P. glauca cone characteristics before assuming more or less independent distributional ranges along the coast of British Columbia.
WATER RELATIONS OF COCONUT PALMS AFFECTED WITH ROOT (WILT) DISEASE
Authors: RAJAGOPAL V. , SUMATHYKUTTYAMMA B. , PATIL K. D.
Published: April 2006

Summary

The water relations of apparently healthy and root (wilt)‐diseased coconut palms (Cocos nucifera L.) were investigated. Leaves of diseased palms had lower stomatal resistances (with relatively high transpiration rates) and leaf water potentials than apparently healthy palms. Although there was a small reduction of osmotic potential in leaves of diseased palms, there was almost complete loss of turgor potential, and flaccidity resulted.
THE HELICOIDAL CELL WALL AS A TIME REGISTER*
Authors: VIAN BRIGITTE , ROLAND JEAN‐CLAUDE
Published: April 2006

Summary

Helicoidal cell walls are characterized by an oscillatory shift in the arrangement of cellulose microfibrils somewhat reminiscent of the rotating movement of the hands of a clock. The periodic movement can be sustained or perturbed. Thus, the helicoidal cell wall presents a temporal reading.

Sensitive to temporal signals, the cell wall keeps a record of cellular events and registers very small variations, storing data at a subcellular level. The present paper emphasizes some aspects of the helicoidal cell wall relevant to timekeeping, revealing its dynamics and flexibility and leading to the question of the mechanisms of its construction.

Contents

I.
Summary
345

II.
Introduction
345

III.
Levels of timekeeping structures
346

IV.
From watch to wall
347

V.
Internal and external alterations
351

VI.
Conclusions
353

References
354
SALT TOLERANCE IN THE HALOPHYTE SUAEDA MARITIMA (L.) DUM.
Authors: CLIPSON N. J. W. , FLOWERS T. J.
Published: April 2006

Summary

Rates of ion transport and transpiration were measured during the day and night in whole seedlings of Suaeda maritima growing over a range of salinities, in order to calculate concentrations of sodium and potassium in the xylem during these periods. Mean sodium concentration in the xylem was maximal at 56 mol m−3 Na with an external salinity of 200 mol m−3 NaCl. The sodium concentration in the xylem was greater in the dark than in the light at all external salinities investigated. Comparison of the external sodium with that in the xylem indicated that sodium was more strongly excluded from the transpiration stream as salinity increased. The mean concentration of potassium in the xylem declined as external NaCl concentration increased, although selectivity for potassium increased at higher salinities. Results are discussed in relation to osmotic adjustment in S. maritima.
QUNTITATIVE ION DISTRIBUTION WITHIN ROOT CELLS OF SALT‐SENSITIVE AND SALT‐TOLERANT MAIZE VARIETIES
Authors: HAJIBAGHERI M. A. , HARVEY D. M. R. , FLOWERS T. J.
Published: April 2006

Summary

Significant varietal differences were apparent in the survival of seedlings of maize in saline conditions but only at relatively high external concentrations (200 mol m−3 NaCl), where there was a range from 0 to 66% survival, 25 d after salinization. For the varieties examined there was a strong negative correlation between Na concentrations in the third leaf and survival. Two resistant varieties (Across 8024 and Protador) and one salt‐sensitive variety (LG11) were identified. The characteristics of ion accumulation were clearly different in salt‐tolerant and salt‐sensitive types, the difference becoming more pronounced with plant age.

The distribution of ions, particular those of Na, K and Cl, was determined within subcellular compartments of roots cells using X‐ray microanalysis of freeze‐substituted tissue. Salinity induced a greater increase (about 1.7 times) in cytoplasmic Na concentration in the salt‐sensitive variety (LG11) than in resistant varieties (Across 8024 or Protador). The mean K:Na ratio in the cytoplasm of the root cortical cells in the salt‐resistant varieties grown for 15 d in saline conditions (100 mol m−3 NaCl) was twice that found for LG11.

Sodium and Cl concentrations in the vacuoles decreased radially inwards from the epidermal cells in salt‐treated roots of LG11.
THE PHYSIOLOGY OF BASIDIOMYCETE LINEAR ORGANS
Authors: CLIPSON N. J. W. , CAIRNEY J. W. G. , JENNINGS D. H.
Published: April 2006

Summary

Phosphate uptake as a function of external medium concentration has been determined for mycelium grown in the laboratory, segments of cords collected from the field and cords in the field for a range of wood‐decay basidiomycetes. Hofstee plots in all cases can be interpreted as indicating the presence of two uptake systems. Uptake of phosphate by mycelium is reduced by increasing the concentration of phosphate in the growth medium from 10 μM to 10 mM. The major portion absorbed by cords in the field remains within the segment exposed to radioactive solution, suggesting conversion of the phosphate to an immobile form unavailable for translocation.
ABSCISIC ACID AND DORMANCY IN ROOT‐NODULATED ALNUS GLUTINOSA (L.) GAERTN.
Authors: WATTS S. H. , WHEELER C. T. , HILLMAN J. R.
Published: April 2006

Summary

Treatment of three‐month or six‐month‐old water culture plants of Alnus glutinosa with 0.1 mol m−3 (±) abscisic acid (ABA) induced formation of resting buds after 30 to 60 d. Leaf dry weight per plant decreased by 40 to 45 % during this period but root and nodule dry weights were unchanged relative to control plants. [2‐14C] ABA was taken up by the root system within 5 d and after 30 or 60 d the ABA content of plants fed 01 mol m−3 ABA was 60 and 119 times that of control plants. In control plants, the levels of ‘free’cis(Z) ABA were similar to or exceeded ‘free’trans(E) ABA in all plant parts while, in general, the converse was true for these isomers in ‘bound’ form. In ABA‐treated plants, all isomeric forms of ABA were present at much higher amounts than in the controls but, whereas in leaves and shoot apices the amount of cis ABA in both ‘free’ and ‘bound’ forms was much greater than the trans isomer, in roots and nodules trans ABA was the dominant isomer in both ‘bound’ and ‘free’ forms. Most biologically active ‘free’cis ABA thus accumulated in the leaves and shoot apex, where effects of ABA treatment on growth were most evident, whereas in roots and nodules where biologically inactive ‘free’ and ‘bound’trans ABA were dominant, growth was relatively unaffected. Amounts of ‘free’ ABA in nodules were several times those recorded previously in nodules of dormant plants, in keeping with earlier suggestions that ABA is unlikely to have a precise regulatory role in growth and dormancy of nodules.
THE EFFECT OF ABSCISIC ACID AND FUSICOCCIN ON MALIC ACID CONCENTRATION IN PULVINI OF PHASEOLUS COCCINEUS L.
Authors: BIAŁCZYK JAN , LECHOWSKI ZBIGNIEW
Published: April 2006

Summary

Fusicoccin and abscisic acid can modify the movements of some nyctinastic plants. This paper reports the effects of these two compounds on the concentrations of malic acid in pulvini of Phaseolus coccineus L. in the transition period of two phases of the circadian rhythm. The concentrations of malic acid in the two parts of the pulvinus, extensor and flexor, depend upon the phase of leaf movements. Abscisic acid and fusicoccin significantly affected the content of malic acid in leaves compared with the control. In the two phases of the diurnal cycle investigated, abscisic acid markedly reduced the production of malic acid in the flexor and extensor regions of the pulvinus, and treatment with fusicoccin produced small but distinct increases in the concentration of malic acid in the same regions. The results are discussed with particular reference to the effect of abscisic acid and fusicoccin on the activity of the H+ pump associated with the control of turgor in cells.
COMPARATIVE STUDIES OF PLANT GROWTH AND DISTRIBUTION IN RELATION TO WATERLOGGING
Authors: TALBOT RICHARD J. , ETHERINGTON JOHN R. , BRYANT JOHN A.
Published: April 2006

Summary

Rooted cuttings of Salix caprea L. and ‐S. cinerea ssp. oleifolia (Macreight) growing in soil were exposed to (a) intermittent, (b) partial and (c) complete waterlogging of the soil. Measurements of growth and other characteristics were compared with unflooded controls. Both species were harmed by waterlogging but S. caprea was more sensitive than 5. cinerea as shown by the greater reduction of height, internode number, dry weight of root, stem and leaf, specific leaf area and leaf area per plant. The waterlogging treatments did not differ amongst themselves in the degree of inhibition of growth which they caused. A single fully waterlogged treatment would thus have been quite adequate in screening for tolerance.

The reduction in specific leaf area of S. caprea was probably mediated by reduced turgidity and failure of leaf tissue to expand fully. Leaf iron content increased in both species but less so in S. cinerea, which is able to immobilize more iron in, or on, its roots. 5. caprea leaves contained over 2000 μg g−1 iron, a concentration recorded as toxic in other plants; these leaves became brittle and some lower leaves were shed. Root iron content increased more in S. cinerea than in S. caprea, and this was accompanied by an increase in phosphorus content. Chlorophyll and magnesium content of leaves was significantly reduced in S caprea but not in S. cinerea. Photosynthetic potential was reduced in S. caprea but not in S. cinerea; this was probably unrelated to stomatal control of CO2 uptake. S. cinerea produced adventitious roots at the surface of flooded soil and when cuttings were immersed in water; S. caprea did not. These observations are compatible with the ecology of the two species, S. caprea normally inhabiting better drained soils than 51. cinerea.
THE EFFECT OF WATERLOGGING ON INFECTION OF EUCALYPTUS MARGIN AT A SEEDLINGS BY PHYTOPHTHORA CINNAMOMI
Authors: DAVISON E. M. , TAY F. C. S.
Published: April 2006

Summary

Three‐ to four‐month‐old Eucalyptus marginata Donn ex Sm. (jarrah) were grown in the glasshouse in peat/sand at 20° C root temperature, infected with zoospores of Phytophthora cinnamomi Rands, added either 10 cm below the soil surface or flooded onto the soil, and various waterlogging regimes were imposed. When plants were infected but not waterlogged, the proportion of infected root length adjacent to the point where zoospores were added was low. More lesions were formed per metre root length on tap roots than on lateral roots, but lesions on lateral roots were longer than on tap roots. When plants were waterlogged for a 4 d period before the addition of zoospores, there was no increase in root infection. When plants were waterlogged at the same time or after the pots were inoculated, there was a significant increase in the proportion of root length infected. This was due to an increase in the number of lesions and not, in four of the five harvests, to an increase in lesion length.

When inoculation and waterlogging were imposed at the same time, the increased number of infections was probably due both to the increased attraction of zoospores to anaerobically respiring roots and to increased zoospore motility in flooded soil. When waterlogging was imposed several days or weeks after the plants had been infected, the increased number of lesions was unlikely to have been due to residual zoospores in the soil, because their numbers declined exponentially. It was also unlikely to have been due to sporangia developing de novo on the roots after waterlogging had been imposed, because the O2 concentration of the soil solution was inadequate. It is probable, therefore, that the new infections originated from zoospores liberated from sporangia already formed on lesions before waterlogging was imposed.

When plants were infected but not waterlogged, there was no effect on the leaf diffusive resistance, leaf relative water content and shoot xylem pressure potential between 1 and 28 d. When plants were flooded, the daily water loss decreased more rapidly and plants died more rapidly in the inoculated and waterlogged treatments than in the treatments which were only waterlogged. Infection by P. cinnamomi did not affect the proportion of xylem vessels occluded with tyloses in seven of the eight unflooded, and seven of the eight flooded, comparisons.
GROWTH AND REPRODUCTION OF SILENE CUCUBALUS WIB. INTERMITTENTLY EXPOSED TO LOW CONCENTRATIONS OF AIR POLLUTANTS, ZINC AND COPPER
Authors: DUECK TH. A. , WOLTING H. G. , MOET D. R. , PASMAN F. J. M.
Published: April 2006

Summary

Populations of Silene cucubalus Wib. which were sensitive or tolerant to heavy metals or sulphur dioxide, were grown in zinc‐ or copper‐supplemented soil and were exposed to mixtures of SO2, O3 and NO2 in low concentrations for a period of 12 weeks. Fumigations were applied only during elevated ambient concentrations of ozone. Growth during fumigations was reduced, but flower production was significantly higher in metal‐tolerant populations when grown in soil supplemented with their specific metal. Flowers were hand‐pollinated when plants were exposed to at least 60 μg m3 O3, 40 μg m3 SO2 and 60 μg m−3 NO2. Although the number of seeds and individual seed weight were significantly influenced by heavy metals and/or air pollutants, it appeared that flower production has the greatest effect on potential sexual reproduction. Plants which have evolved resistance to pollution express optimal reproductive capacity when grown in soil most resembling their native soil. The interpretation and comparison of results gained under experimental conditions are discussed with respect to field observations and effects of pollutant/species combinations.
ABSENCE OF ASPECIALIZED INTERFACE BETWEEN INTRACELLULAR HYPHAE Of COLLETOTRICHUM LINDEMUTHIANUM AND CELLS OF PHASEOLUS VULGARIS
Authors: O'CONNELL R. J.
Published: April 2006

Summary

The intracellular infection vesicles and primary hyphae of Colletotrichum lindemuthianum (Sacc. & Magn.) Briosi & Cav. invaginate protoplasts of cells of Phaseolus vulgaris L. A matrix composed partly of polysaccharide or glycoconjugates containing vicinal hydroxyl groups separates the fungal wall from the host plasmalemma. Coated vesicles appear to release host material into the matrix by exocytosis. The invaginated region of the host plasmalemma stains normally with phosphotungstic acid, retains adenosine triphosphatase activity and appears normal when freeze‐fractured. This contrasts with the highly modified host plasmalemma surrounding haustoria of many obligately biotrophic fungi. The absence of a specialized host‐parasite interface is discussed in relation to the transient nature of biotrophy in the bean anthracnose disease.
SOMATIC INCOMPATIBILITY AND FIELD DISTRIBUTION OF THE ECTOMYCORRHIZAL FUNGUS SUILLUS LUTEUS (BOLETACEAE)
Authors: FRIES NILS
Published: April 2006

Summary

Tissue isolates were collected from 25 basidiocarps of Suillus luteus (L. ex Fr.) S. F. Gray under pine trees (Pinus sylvestris L.) at nine sites in a small forest area (approximately 1 km2) and tested for somatic incompatibility. Eleven distinct clones were detected, none of which was found in more than one site. This ectomycorrhizal fungus therefore possesses a population structure similar to that of many wood‐decomposing basidiomycetes.
HYDROXYLAMINE METABOLISM IN MONORAPHIDIUM BRAUNII
Authors: BALANDIN TERESA , APARICIO PEDRO J.
Published: April 2006

Summary

The utilization of nitrate by cells of Monoraphidium braunii Legnerová was immediately impaired by low concentrations of hydroxylamine. The consumption of NO3− resumed when almost no hydroxylamine was left in the culture medium but resumption took place only under illumination with blue light. The addition of hydroxylamine to cell suspensions caused the rapid inactivation of nitrate reductase. The inactivation was largely prevented by the previous incubation of the cells with menadione, a rinding which suggests that hydroxylamine inactivates the reduced form of nitrate reductase. Illumination of cells previously treated with hydroxylamine promoted the in situ reactivation of the enzyme.
ULTRASTRUCTURAL DISTRIBUTION OF GLUTAMATE DEHYDROGENASES DURING FRUIT BODY DEVELOPMENT IN COPRINUS CINEREUS
Authors: ELHITI MAYSOON M. Y. , MOORE DAVID , BUTLER R. D.
Published: April 2006

Summary

Techniques based on a copper ferricyanide method were developed for the cytochemical localization at the ultra structural level of NAD‐ and NADP‐linked glutamate dehydrogenases (NAD‐GDH, NADP‐GDH), the latter enzyme being specifically involved in mushroom cap development. These techniques were validated using malate, lactate and succinate dehydrogenases (MDH, LDH, SDH). Tests were applied to unfixed and formaldehyde‐fixed material from three developmental stages of fruit bodies of Coprinus cinereus (Schaeff.: Fr.) S.F. Gray sensu Konr. (1) before spore formation (stage 2), (2) with young spores (stage 3), and (3) with mature spores (stage 4). Spectrophotometric assay showed that NADP‐GDH was still detectable after 15 min formaldehyde fixation and approximately 9 and 80% activity of NAD‐GDH and MDH, respectively, was preserved. At all stages of development MDH, LDH and SDH activities were localized in mitochondria or mitochondrion‐like bodies. In contrast, both NAD‐GDH and, especially NADP‐GDH, were localized in cytoplasmic vesicles, mainly in basidia and very young spores, sometimes being found adjacent to the cell walls, suggesting that these enzymes are transported to the vicinity of the plasma membrane. Such a location would be consistent with enzymological data, indicating that NADP‐GDH contributes to an ammonium scavenging system. Ultra structural localization of this system at the peripheral region of basidia suggests it may be linked to the synthesis and/or assembly of cell wall components and may protect the meiotic apparatus against ammonium inhibition.
INTERACTIONS BETWEEN INTERNAL AND EXTERNAL CO2 POOLS IN THE PHOTOSYNTHESIS OF THE AQUATIC CAM PLANTS LITTORELLA UNIFLORA (L.) ASCHERS AND ISOETES LACUSTRIS L.
Authors: MADSEN TOM VINDBÆK
Published: April 2006

Summary

The significance of CAM as a carbon‐conserving mechanism in two submerged aquatics, Littorella uniflora (L.) Aschers and hoetes lacustris L., was evaluated by determining (1) the loss of previously fixed CO2, released through decarboxylation of malic acid and (2) the quantitative importance of CAM relative to external CO2 uptake in photosynthesis.

Using a 14C‐labelling technique it was found that the loss of CO2 derived from decarboxylation of malic acid constituted less than 2 % of nocturnal carbon uptake, confirming that the diurnal rhythm of acidity provides a good measure of the incorporation of carbon via CAM.

The exchange pattern of inorganic carbon and oxygen was measured for plants incubated in open flow‐through systems. The contribution of internal and external CO2 to photosynthesis was determined as the difference in CO, uptake and oxygen release, where excess oxygen release reflected the assimilation of CO2 released from deacidification of malic acid. Despite a rapid deacidification, uptake of external CO2 was stimulated by 15 to 30% at intermediate external CO2 concentrations. It is suggested that this effect was due to a reduced photorespiratory activity caused by an enhanced internal CO2 concentration generated from malic acid. The simultaneous uptake of inorganic carbon from high internal and low external CO2 concentrations can only be explained by assuming a non‐linear CO, gradient from the lacunal air to the bulk medium, with the CO2 concentration in the outermost cell layers being lower than both the bulk medium and the lacunal air.

The relative contribution of CAM to the total uptake of CO2 in daytime declined from 95% (both species) at an external CO2 concentration of 30μ CO2 to 38% (Littorella) and 34% (Isoetes) at 200μ CO2. This resulted from increased uptake of external CO2 at high external CO2 concentrations and a parallel suppression of internal decarboxylation of malic acid.

The observed suppression of decarboxylation was confirmed by following the time course in the content of titratable acidity of the leaves. A reversible inhibition of daytime deacidification was seen for external CO2 concentrations higher than 3.0 to 5.4 mM CO2 in both Littorella and Isoetes.

The functional significance of CAM for aquatics rests in the enhanced capacity for obtaining inorganic carbon resulting from the extension of the diel period in which inorganic carbon can be accumulated and in the high reassimilation efficiency of nocturnal respiratory CO2.
NITROGEN FIXATION (ACETYLENE REDUCTION) BY FOREST LEGUMES: SENSITIVITY TO PRE‐HARVEST AND ASSAY CONDITIONS
Authors: GROVE T. S. , MALAJCZUK N.
Published: April 2006

Summary

The effects of environmental and methodological factors on acetylene reduction by nodules of Acacia pulchella R.Br., Kennedia coccinea Vent, and K. prostrata R.Br. grown in pots were studied.

The time course of acetylene reduction, measured for each species during assays lasting up to 3 h, showed that there was an initial lag phase before maximum rates were reached and that rates then declined rapidly. This decline in activity was less marked for K. prostrata than for the other two species. Rates of acetylene reduction did not differ significantly between detached nodules, roots with attached nodules and whole plants.

Delaying the introduction of acetylene into assay vessels indicated that the decline in nitrogenase activity during assays at higher temperatures was only partly caused by the acetylene substrate. As weights of nodules were small in relation to the volume of assay vessels, the decline in activity is unlikely to result from changes in pO2. The initial lag phase was shorter and the decline in activity with time more marked with increasing temperature. This finding has important implications for conducting and interpreting field assays, and in determining optimum temperatures for nitrogenase activity.

Calibration factors relating acetylene reduction to nitrogen fixation were estimated from measurements of nitrogen accumulation and acetylene reduction during growth of young plants in a nitrogen‐free sand. Ratios for A. pulchella (2·5:1) and K. coccinea (2·4:1) were lower than theoretical ratios (3 to 4:1), probably because of the decline in rates of acetylene reduction during assays. Lowering of irradiance to about 4 % of full sunlight over 2 d depressed acetylene reduction rates by 58% for A. pulchella and by 36% for K. coccinea.
DIAZOTROPHIC REGULATION OF AKINETE DEVELOPMENT IN THE CYANOBACTERIUM ANABAENA DOLIOLUM
Authors: RAO V. V. , GHOSH RITA , SINGH H. N.
Published: April 2006

Summary

Cessation of growth with N2, NO3− or NH4+ as nitrogen source marked the beginning of akinete differentiation in Anabaena doliolum. The primary trigger of the differentiation process during diazotrophic growth conditions appeared to be the generation of a nitrogen starvation signal resulting from progressive loss of the activities of nitrogenase and glutamine synthetase. Persistence of a substantial level of oxygenic photosynthetic activity long after the cessation of diazotrophic growth and the initiation of akinete development suggests a role for oxygenic photosynthesis in the process of akinete development subsequent to its initiation. The loss of diazotrophy much earlier than that of oxygenic photosynthesis explains the observed increase in the C/N ratio occurring during initiation and the middle phase of akinete formation. Both the initiation of akinete development subsequent to cessation of diazotrophic growth and the rise in the C/N ratio during the early and middle stages of akinete formation appear to be regulated by a developmental mechanism similar to the one that functions in the control of nitrogenase and glutamine synthetase activities during diazotrophic cyanobacterial growth.
EFFECT OF NODULATION ON THE EXPRESSION OF NITRATE REDUCTASE ACTIVITY IN PEA CULTIVARS
Authors: LIGERO F. , LLUCH C. , HERVAS A. , OLIVARES J. , BEDMAR E.J.
Published: April 2006

Summary

Nitrate reductase activity (NRA) was measured in leaves, stems, roots and nodules of four cultivars of Pisum sativum L. supplied with 2 mM KNO3 and nodulated by selected Rhizobium leguminosarum strains. As a control, non‐nodulated (uninoculated) plants were grown in the same nutrient medium. NRA was determined by an in vitro assay; it varied widely among strains and cultivars. Although differences in tissue NRA in nodulated plants were mainly related to cultivar genotype, nodulation much affected the distribution of NRA within the plant. There was also some cultivar x bacteria strain effect. Non‐nodulated plants had higher leaf and root NRA than nodulated cultivars, but nodulated plants had twice as high stem NRA as non‐nodulated plants. These differences correlated with nitrate concentrations which were depressed in leaves and roots, and increased in stems, of nodulated plants Nitrate accumulation was increased in leaves, stems and roots of nodulated plants in comparison with non‐nodulated ones. There were no differences in the root to shoot ratio between nodulated and non‐nodulated plants. The relationships between tissue nitrate reduction and nodulation are discussed.
RESPIRATION OF LEAVES OF BARLEY INFECTED WITH POWDERY MILDEW: INCREASED ENGAGEMENT OF THE ALTERNATIVE OXIDASE
Authors: FARRAR J. F. , RAYNS F. W.
Published: April 2006

Summary

Leaves of barley cv. Maris Otter, susceptible to powdery mildew, show a large increase in respiration rate when infected with this fungus. About half of the increase is due to increased electron flow through the cytochrome chain and half through the alternative pathway. The alternative pathway shows increased engagement following infection but no increase in capacity. Respiration is not limited either by substrate or supply of inorganic phosphate. While the increase in activity of the cytochrome path may be due to adenylate regulation, that of the alternative path is not understood. The more resistant cvs Athos and Atem do not show alternative path activity following infection with mildew.
EFFECT OF MEDIA ON GROWTH AND INTERACTIONS BETWEEN A RANGE OF SOIL‐BORNE GLASSHOUSE PATHOGENS AND ANTAGONISTIC FUNGI
Authors: WHIPPS JOHN M.
Published: April 2006

Summary

The growth of and interactions between the glasshouse pathogens,Rhizoctonia solaniKühn,Fusarium oxysporumSchlect.,Pyrenochaeta lycopersiciSchneider & Gerlach,Phomopsis sclerotioidesvan Kesteren,Sclerotinia sclerotiorum(Lib.) de Bary andBotrytis cinereaPers. and the antagonistic fungi,Trichoderma harzianumRifai,Trichoderma viridePers.,Coniothyrium minitansCampbell,Gliocladium roseum(Link.) Bain andPythium oligandrumDreschler were examined on tap water agar, soil extract agar and potato dextrose agar. The medium had a significant effect on the growth rates of the fungi as well as the production of, and response to, volatile and non‐volatile antibiotic compounds and hyphal interactions. Responses to the media appeared to be related both to inherent properties of the fungi and to their natural ecological behaviour. The significance ofin vitroassays in screening systems for biological control agents of soil‐borne plant pathogens is discussed.
THE NATURE OF THE VEGETATIONAL CHANGES AT ABOUT 5000 b.p. WITH PARTICULAR REFERENCE TO THE ELM DECLINE: FRESH EVIDENCE FROM CONNEMARA, WESTERN IRELAND
Authors: MOLLOY KAREN , O'CONNELL MICHAEL
Published: April 2006

Summary

Results of palaeoecological investigations on a core from Lough Sheeauns, N.W. Connemara, a small lake sited in an area with a dense concentration of megaliths datable to the Neolithic, are reported. Pollen analysis, involving continuous sampling over a 41 cm interval spanning the elm decline (c. 5000 B.P.), permitted a detailed reconstruction of the vegetational changes and the nature of human impact. The pollen data are supplemented by chemical analysis and a chronology is provided by radiocarbon dating.

Farming, including cereal cultivation, in the century prior to the elm decline is demonstrated. The elm decline emerges as a distinct feature in both percentage and concentration pollen diagrams. It is argued that neither an anthropogenic nor a climatic explanation for that event is sustainable in the light of the available evidence; a disease hypothesis is favoured. In the immediate post‐elm decline period, Landnam, involving major woodland clearance in the context of a pastoral‐based Neolithic economy, is recorded as a distinctive feature in the pollen record.
Recent advances in palaeomycology
Authors: STUBBLEFIELD SARA P. , TAYLOR THOMAS N.
Published: April 2006

summary

The fossil record is a long‐neglected source of valuable information concerning the diversity, structure, evolution and activities of ancient fungi. However, interest in these organisms has increased in recent years as their importance in a wide variety of interactions with plants, animals and the geological environment has been recognized. Evidence from the fossil record now implicates fungi in such processes as the establishment of terrestrial plants, degradation of lignin in Devonian forests, parasitic relationships with plants and animals, and the development of ancient soils. Although fossil fungi remain difficult to study, their geological record is rich and rewarding. Recent advances in the study of fungi from the Palaeozoic and early Mesozoic (exclusive of palynological research) are presented in this review.

CONTENTS

Summary

I.
Introduction
3

II.
Fungal diversity
4

III.
Interactions between fungi and their environment
7

IV.
Evolution of fungi
12

V.
Special problems in studying fossil fungi
14

VI.
Future research in palaeomycology
16

Acknowledgements
17

References
17
The effects of root treatments on growth of the primary leaves of Phaseolus vulgaris L.: General features
Authors: MILLIGAN S. P. , DALE J. E.
Published: April 2006

summary

Seedlings of Phaseolus vulgaris, grown at 22.5 °C in moist vermiculite for 7 days, were transferred to nutrient solution held either at ambient temperature or at 10 °C, or subjected to a root–pruning treatment which removed all lateral roots and part of the main root. The effect of both treatments was to reduce primary leaf growth rate, within 3–6 h in the one case and 12 h in the other. The lower growth rate was maintained for the whole of the expansion period so that the final size of primary leaves on treated plants was only 35–40% of the controls. The smaller leaf size was caused by a reduction in average cell size judged from epidermal cell surface area and anatomical studies. Cell number per leaf was not affected by treatment. Root cooling caused an ephemeral initial fall in bulk leaf water potential, estimated by pressure chamber, but water stress was not thought to be the cause of the inhibition of leaf growth.
Effects of simulated acid rain on leaf wettability, rain retention and uptake of some inorganic ions
Authors: PERCY K. E. , BAKER E. A.
Published: April 2006

summary

Leaves of Phaseolus vulgaris L., Vicia faba L., Pisum sativum L. and Brassica napus L. were exposed from emergence to full expansion to seven treatments of simulated acid rain at pH values between 5.6 and 2.6. Droplet leaf contact angles in all species decreased on leaves exposed to simulated acid rain at pH <4.6 relative to those exposed at pH 5.6. Retention of rain containing fluorescein increased on P. vulgaris leaves exposed to simulated acid rain at pH 4.6 and at pH < 3.8. Retention by B. napus leaves was increased at pH < 4.6. Uptake of the three ions studied was in the order 86Rb+≤35SO42−≤63Ni2+. Uptake of 86Rb+ increased into B. napus leaves and decreased into P. vulgaris leaves exposed at pH ≤ 3.4. Uptake of 35SO42− and 63Ni2+ by B. napus leaves increased after exposure to simulated acid ruin at pH 2.6 but it was unaffected in P. vulgaris. Up to 7%, of applied 35SO42−, was found in the epicuticular wax layer on B. napus leaves 48 h after application, most being found after exposure at pH 2.6. The order of lateral movement of ions within leaves paralleled the order of uptake. Movement of all three ions was increased in B. napus leaves exposed previously to simulated acid rain at pH 2.6. The increased retention of fluorescein on leaves exposed to simulated acid rain and the reduced contact angles for water are attributed to decreases in surface roughness. The altered ion uptake pattern could also be related to changes in surface wax structure or could be associated with observed changes in properties of cuticular membranes. These results demonstrate that the interaction of plants with their atmospheric environment could possibly be affected by pre‐exposure to acid rain in amounts and at pH values that occur in ambient rainfall.