bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogeny of progymnosperms. I. Shoots of Upper Devonian Aneurophytales
Authors: Scheckler Stephen E.
Published: September 2008

Configurations of the primary xylem strands of the progymnosperms Tetraxylopteris schmidtii, Triloboxylon ashlandicum, and Proteokalon petryi (Aneurophytales) have been determined for most levels of their shoot systems. In general there is a decrease in diameter of xylem and number of protoxylem strands from proximal to distal branchings. Variation, however, occurs within each order of branching. Primary xylem of vegetative branches is smallest at the proximal and distal ends and largest in the midregions. Size and form of primary xylem of living plant axes seem to relate to size (volume) and vigor (potential for growth) of their apical meristems. Thus the variation of primary xylem found in vegetative axes of these Aneurophytales may reflect epidogenetic, menetogenetic, and apoxogenetic episodes of apical growth of these organs. Fertile organs and vegetative ultimate appendages differ by having primary xylem strands that are largest proximally and that decline with each more distal division. This reflects the apoxogenetic growth of their apices and suggests that these organs are appendicular. Vegetative branches of all three plants seem to be at first indeterminate but eventually become determinate. Distal branches appear to have less potential for growth than proximal ones. Ultimate appendages and fertile organs differ by being fully determinate. The type of organ that a primordium becomes is rigidly fixed in Aneurophytales and, judging from the diameter of its trace, may relate to the size of the primordium itself rather than to the size of the parental axis. One may postulate that above a size threshold a primordium develops into a branch with indeterminate potential (expanding apical volume). Below that threshold a primordium is determinate (contracting apical volume) and develops into either a fertile organ or an ultimate appendage, depending on its position within the branching system. Determinate primordia on the last order of vegetative branches develop into the dichotomous ultimate appendages. Determinate primordia on other orders of vegetative branches develop into dichotomous fertile organs.
Developmental morphology of Triangularia backusii (Sordariaceae)
Authors: Huang L. H.
Published: September 2008

Perithecia of Triangularia backusii are initiated by a coiled ascogonium that consists of several uninucleate cells. No trichogynes are produced. Sterile hyphae which originate from stalk cells of the ascogonium envelop the ascogonium and develop into an outer zone that forms part of the peridium. Hyphae arising from the base of the ascogonial coil develop into two types of tissues: the middle zone forms part of the peridium and the inner zone forms the pseudoparenchymatous centrum tissue. When the young perithecium reaches a diameter of about 110 μm, the central mass of ascogonial hyphae spreads out as a result of perithecium growth and the pressure from the upward growing paraphyses, and the ascogenous hyphae start to develop from the ascogonial hyphae. At the same time periphyses begin to grow in the apical region. The uninucleate paraphyses and periphyses originate from large, thin-walled, multinucleate pseudoparenchyma cells. Asci appear when the young perithecium has assumed an ovoid shape and attained a diameter of about 140 μm. Each uninucleate ascogenous cell grows out into a uninucleate hook and the hook develops directly into an ascus.Elongation of asci and paraphyses and enlargement of core hyphae and pseudoparenchyma cells expand the perithecium, and disintegration creates a central cavity. Growth and enlargement of hyphae of the middle zone result in the formation of the perithecial neck. Periphyses continue to grow upward or horizontally until an ostiolar canal is formed. At maturity the pseudoparenchyma zone is thin at the sides but thick at the ostiolar region and bottom.Chadefaud's concept of the Sordariales is expanded to include four families: Chaetomiaceae, Lasiosphaeriaceae, Microascaceae, and Sordariaceae. These families include those fungi with the Sordaria type of centrum development proposed herein.
The biology of Harveyella mirabilis (Cryptonemiales, Rhodophyceae). IV. Life history and phenology
Authors: Goff Lynda J. , Cole Kathleen
Published: September 2008

A 20-month field study of the reproductive biology of the parasitic red alga Harveyella mirabilis was undertaken to investigate the effects of environmental parameters on the reproductive periodicity of Harveyella in the intertidal habitat. In the northeast Pacific, tetraspores have been observed in the late winter - early spring; apparently they are produced in response to increased available sunlight and water temperature. Gametogenesis appears to be temperature sensitive; it occurs between a narrow temperature range (9–11 °C). Carpospores are produced in the late summer when both water temperature and day length reach a peak. The phenology of H. mirabilis in the North Atlantic differs from that which is observed in the North Pacific in the timing of gametogenesis and carposporogenesis. The significance of this is discussed in relation to the possible effects of differences in seawater temperature on gametogenesis.
Leaf curl disease of almond caused by Taphrina deformans. III. Ultrastructural cytology of the pathogen
Authors: Syrop Mary , Beckett A.
Published: September 2008

The formation of ascogenous cells of Taphrina deformans (Berk.) Tul. from vegetative hyphae and their subsequent development have been investigated with the electron microscope. Ascus formation, ascosporogenesis, ascospore budding, and spore discharge are described. Nuclear pairs occur in vegetative and ascogenous cells. Spindle pole bodies of nuclear pairs are often closely associated. Two spindle pole bodies that are associated with each nucleus have been observed in ascogenous cells, ascus initials, and asci. Endoplasmic reticulum cisternae are numerous in vegetative hyphae but are absent in reproductive cells. Networks of smooth membranes are located in ascogenous cells. The ascus wall is unitunicate and splits at the ascus apex to release the ascospores. Ascospores may bud before or after their release.
Genetic adaptation for seed dormancy in Avena fatua
Authors: Naylor J. M. , Jana S.
Published: September 2008

Genetic variability affecting duration of primary dormancy is demonstrated in natural populations of wild oats. Marked differences were found among local populations in germination behavior. The evidence suggests that these differences result in part from genetic adaptation to agronomic practices.
Bud development in Sitka spruce. I. Annual growth cycle of vegetative buds and shoots
Authors: Owens John N. , Molder Marje
Published: September 2008

Vegetative apices of Picea sitchensis (Bong.) Carr. were studied throughout the annual growth cycle. Apices became mitotically active late in March and the shoot axis and leaf primordia elongated causing the bud to swell. New axillary apices were initiated in mid-April and the terminal apex and new axillary apices initiated bud scales until early in July. Vegetative bud burst occurred early in June and shoot elongation was completed by mid-July. The end of shoot elongation coincided with the onset of leaf initiation. The change from bud-scale to leaf initiation was characterized by a period of increased mitotic activity and rapid apical growth. About half of the final number of leaves were initiated during the early period of rapid leaf initiation. The remaining leaf primordia were initiated more slowly over the next 3 months. Buds became dormant by mid-November.
Aggregation of sand-dune soil by endomycorrhizal fungi
Authors: Sutton J. C. , Sheppard B. R.
Published: September 2008

The mycorrhizal fungus Glomus in association with bean hosts (Phaseolus vulgaris L.) was the dominant factor in the aggregation of sand particles in sterilized dune soil artificially inoculated either with Glomus, or with Glomus and a soil extract containing miscellaneous microorganisms. The weight of sand adhered to roots harvested from dried soil was about 3 times greater in mycorrhizal than in nonmycorrhizal roots. The weight of sand aggregates per kilogram dried soil from among roots of senescent beans was 10 g in nonmycorrhizal plants but 54 g in mycorrhizal plants. The fungitoxicant benomyl prevented mycorrhizal development and markedly restricted sand aggregation on and among roots of beans grown in soil inoculated with Glomus. A soil extract enhanced mycorrhizal development, the amount of sand adhered to mycorrhizal roots, and the extent of sand aggregation among mycorrhizal roots. Based on microscopic observations, the major mechanism linking sand grains in aggregates was the binding of sand to extensive Glomus mycelia.
Physiological aspects of carbon monoxide production by the brown alga Nereocystis luetkeana
Authors: Foreman Ronald E.
Published: September 2008

The pneumatocyst gases of those members of the Phaeophyta which possess single, large pneumatocysts (Nereocystis sp., Pelagophycus spp., and Eklonia spp.) contain CO. Although CO is produced by a number of algae, internal retention is unique to the above-mentioned genera. This study was undertaken to examine the physiological aspects of CO origin and retention in pneumatocysts of Nereocystis. A new hypothesis to explain this phenomenon consists of three parts: firstly, that CO production is a by-product of autolytic cell metabolism which is linked to respiration by a requirement for energy, probably in the form of ATP: secondly, the occurrence of CO in the pneumatocysts of large kelps is the result of autolytic processes that are active in pneumatocyst formation; and thirdly, CO concentrations in the pneumatocyst are determined by the production rate and loss rate by diffusion into the surrounding environment through the pneumatocyst wall. The CO-producing pathway has a heat-labile component which indicates enzyme involvement in production.The presence of a CO- and CN-sensitive electron-transport system is shown, although the existence of cytochrome a–a3 could not be demonstrated. Sufficient CO production can be obtained after homogenization and fractionation to permit further biochemical investigation.
Response of the vascular cambium to reorientation in patch grafts
Authors: Thair B. W. , Steeves T. A.
Published: September 2008

The vascular cambium was reoriented in square 5-mm panels of bark at 90° and 180° from the normal position in three varieties of Malus baccata and Malus sylvestris (ornamental crabapple), Cornus stolonifera, Sorbus aucuparia, and Thuja occidentalis, Douglasii pyramidalis. Panels grafted in the normal orientation served as controls. The cambium in the panels continued to function normally, and where it was reoriented, it retained the imposed orientation. The secondary vascular tissues that were produced likewise retained the imposed orientation, a feature which was particularly striking in the case of transversely oriented panels. In early growth after the grafting, the secondary xylem showed some histological abnormalities particularly in abnormally oriented panels, but these diminished in later-formed xylem in the case of normally and transversely oriented panels. It is concluded that the cambial initials possess a high degree of autonomy which is reflected in their resistance to realignment which would correspond to the lines of flow of nutrients and water in an axis into which they are grafted.
Sorbitol and sucrose as carbon source for callus culture of some species of the Rosaceae
Authors: Coffin Robert , Taper C. D. , Chong Calvin
Published: September 2008

Initiation of stem callus cultures on a nutrient medium with either 3% sucrose and (or) 3% sorbitol as carbon source was attempted with 17 species selected from the following genera of the Rosaceae: Amelanchier, two spp.; Crataegus, one sp.; Malus, one sp.; Prunus, nine spp.; Pyrus, one sp.; Sorbus, two spp.; and Spiraea, one sp. In the case of Malus pumila var. niedzwetzkyana (crabapple), sucrose and sorbitol media were equally effective in callus initiation, and equal growth was maintained on these media. Callus of Spiraea vanhouttei was initiated only on sucrose medium and no callus of Prunus tenella formed on either medium. With all other species, callus was initiated and (or) gave better growth on further subculture on sucrose than on sorbitol medium, except for Prunus persica (peach), which grew better on sorbitol.
Light-dependent morphogenesis of conidia of Trichometasphaeria turcica in vitro
Authors: Benedict W. G.
Published: September 2008

Induced changes in morphogenesis of developing and germinating conidia of Trichometasphaeria turcica Luttrell (Helminthosporium turcicum Passerini) exposed to various intensities and wavelengths of light were studied. A method to evaluate production of conidia on irradiated mycelium is described. Conidial production and germination were directly correlated with the quantity and quality of incident energy utilized. In white light highest conidial production occurred at an intensity of 23 000 ergs/cm2 s. Green light (515 nm) significantly further enhanced conidial production. Primary hyphae of conidia exposed to green light produced appressoria when germinated in white light. Hyphae of conidia exposed to orange light (640 nm) were branched or curled without appressoria. Only sensitivity to incident energy could account for the behaviour of T. turcica in vitro and by inference account for the pathogenic adaptation of this fungus in the reflected green light of the sweet-corn leaf surface.
Development of bundle sheath chloroplasts in rice seedlings
Authors: Miyake Hiroshi , Maeda Eizo
Published: September 2008

A developmental process of bundle sheath chloroplasts in rice seedlings is examined and compared with that of mesophyll chloroplasts. Chloroplast development is accompanied with the leaf development. Both types of chloroplasts accumulate starch derived from endosperm in the early stages of the leaf development, and the accumulated starch is dissipated during the leaf development. In contrast with mesophyll chloroplasts, bundle sheath chloroplasts accumulate large amounts of starch, appear as spherical, amyloplast-like structures, and preserve the starch up to the late stages of the leaf development. It is suggested that bundle sheath chloroplasts of rice seedlings are specialized in the accumulation and supply of storage starch, which is presumed to be consumed for the leaf development.
Qualitative and quantitative effects of radiation on pycnidial formation by Dendrophoma obscurans
Authors: Binder Frank L. , Lilly V. G.
Published: September 2008

Cultures of Dendrophoma obscurans grown on a 10:2 glucose: casein hydrolysate medium require radiation for sporulation. Far-ultraviolet (253.7 nm), near-ultraviolet (300–425 nm), and blue radiation (400–525 nm) were effective in initiating pycnidial formation. Exposure of cultures to radiation from 500 to 850 nm did not induce sporulation. Pycnidial formation was found to be photoinduced and age dependent. Low intensities of near-ultraviolet radiation administered over long durations were more effective than high intensities of short durations for inducing pycnidial formation.
Induction des périthèces de Nectria galligena Bres. par un photocomposé mycélien absorbant à 310 nm
Authors: Dehorter B.
Published: September 2008

Perithecium photo-induction in Nectria galligena Bres. is accompanied with the biosynthesis of a compound which shows an absorption maximum at 310 nm and is conventionally called 'P 310.' The formation of both this compound and ascocarps requires similar light conditions, namely wavelengths shorter than 600 nm, but contrary to 'P 310' biosynthesis, which is solely photodependent, sexual reproduction is dependent upon all the external factors: light, temperature, environment.Adding 'P 310' to the culture medium shows that this compound is photomimetic, since it induces fertile perithecia in N. galligena in continuous darkness. This study demonstrates relations between sexual reproduction, 'P 310' synthesis, and light action in N. galligena. [Traduit par le journal]
Floral development of Zannichellia palustris
Authors: Posluszny U. , Sattler R.
Published: September 2008

What, at maturity, appears to be a bisexual flower in the axil of one of two subopposite leaves, is revealed as a fertile nodal complex with quite different organization. Three appendages develop at each nodal complex. The first girdles the stem and becomes at maturity a membranous sheath about the entire node. The second subtends the axillary meristem, which terminates as the staminate flower, and branches laterally as a renewal growth in the axil of a sterile appendage just below the stamen. The third appendage is subopposite the terminal meristem, which gives rise to the pistillate floral bud towards the staminate flower, and a renewal growth apex towards the appendage. This renewal growth apex repeats the entire pattern at almost a 90° shift to the right or left, depending on the shoot. The single stamen of the staminate flower develops as those studied in Potamogeton and Ruppia. The pistillate flower develops two carpel primordia, which become peltate before initiating a single ovule primordium on the adaxial portion (Querzone). The membranous envelope which covers the carpels at maturity is initiated at ovule inception, below one of the carpels. A peltate stigma differentiates on a short style and at maturity becomes broad and lobed. The renewal growth apex has a one-layered tunica. The membranous sheaths of the node and of the pistillate flower are primarily protodermal in origin, while the rest of the sterile and reproductive appendages arise through activity in subprotodermal cells. Procambial development is acropetal closely following primordial inception. Each organ (sterile or fertile) receives one procambial strand, except for the membranous sheath about the node and the one about the pistillate flower.
A novel approach to sampling Vaccinium populations
Authors: Kloet S. P. Vander
Published: September 2008

A novel approach to sampling Vaccinium populations is proposed and tested. This technique was developed primarily for biosystematic studies where the researcher has a large area to cover in a short time, but it has a wider potential for plant populations. The procedure involves collection of two to seven open-pollinated berries from the sample area and the separation and germination of seeds. The resulting progeny does not significantly differ from the parent population.
Ultrastructural studies on exogenously dormant ascospores of Daldinia concentrica
Authors: Beckett A.
Published: September 2008

Exogenously dormant ascospores of Daldinia concentrica have been studied using light and electron microscope techniques. Tests have shown that ascospores are rendered non-viable after 10 min treatment with fixative. Thin sections and shadowed, chemically cleaned preparations revealed a multilayered ascospore wall, parts of which are differentiated to form a longitudinal germ fissure. A microfibrillar component is associated with the germ fissure, and enzymic digestion indicates that these fibrils could be chitin. It is also suggested that sporopollenin may be present in certain wall layers.
A contribution to the taxonomy of the Potentilla pensylvanica complex in North America
Authors: Kohli B. , Packer John G.
Published: September 2008

Investigation of this complex has revealed in North America the presence of three chromosome numbers, 2n = 14, 2n = 28, and 2n = 56. The latter two are widespread and correspond to the previously recognized species P. pensylvanica L. and P. bipinnatifida Hook. The diploid, which is rather local in distribution, compares well with the description of P. atrovirens Rydb. and has on occasions been determined as such. The type specimen of P. atrovirens is, however, clearly a form of P. pensylvanica and the diploid has never received formal taxonomic recognition. It is described here and named Potentilla finitima Kohli and Packer n.sp.
Cation-exchange equilibrium and mass balance in the lichen Umbilicaria muhlenbergii
Authors: Nieboer E. , Lavoie P. , Sasseville R. L. P. , Puckett K. J. , Richardson D. H. S.
Published: September 2008

Equilibrium studies on the thallus of U. muhlenbergii (Ach.) Tuck. confirmed that the mass balance of the exchange of Ni2+ for Sr2+, Sr2+ for Tl+, and Sr2+ for H+ was consistent with a cation-exchange mechanism of metal-ion uptake.
Fungi associated with root diseases of aspen in Wyoming
Authors: Ross William D.
Published: September 2008

Ganoderma applanatum (Pers. ex Wallr.) Pat., a Phialophora sp., and possibly Coprinus atramentarius (Bull. ex. Fr.) Fr. showed a potential for causing locally severe damage to aspen in Wyoming. Cytospora chrysosperma Pers. ex Fr., Pholiota squarrosa (Pers. ex Fr.) Quel., an Ascocoryne sp., Pleurotus ostreatus (Jacq. ex Fr.) Kummer, Armillariella mellea (Vahl. ex Fr.), and a Libertella sp. all were associated with root diseases. Phellinus tremulae Bond. et Boris was not found in roots. Chemical evidence for the decay potential is given for six of the most frequently isolated fungi.
Relation of aspen root size to infection by Ganoderma applanatum
Authors: Ross William D.
Published: September 2008

Ganoderma applanatum (Wallr.) Pat. infected only root segments larger than 2.5 in. diam (in the laboratory) and competed very effectively with non-hymenomycetes in large roots in the laboratory but died out in their presence in small roots. Infection in the forest was restricted to within 2.5 ft of infected stumps when roots at the stumps were less than 2.5 in. diam.It is proposed that root rot centers may be more prevalent on the good aspen sites because roots become larger earlier than on poor sites.
Presymptomatic detection of Fusarium wilt of tomato by electrical resistance measurement as related to pectic enzyme production
Authors: Caruso Frank L. , Tattar Terry A. , Mount Mark S. , Malia Margaret E.
Published: September 2008

Decreases in electrical resistance (ER) of tomato taproots were correlated with the progression of Fusarium wilt disease. Production of polygalacturonase (PG) from four isolates of Fusarium oxysporum f. sp. lycopersici, as determined from ammonium sulfate fractions, was correlated with the degree of virulence of each isolate. A drop in ER in tomato plant taproots at 6 cm below the soil level was noticed within 2 h after separate inoculation with all strains. These drops in ER preceded foliar symptom development by 20 h. Measurement of ER in the stems of inoculated tomato plants, however, was found to be no different from that of uninoculated plants. The rate of ER decrease was correlated with the in vitro production of PG by these isolates; the higher the PG activity, the greater the decrease in ER.
Some possible sources of error in determining bulk elastic moduli and other parameters from pressure–volume curves of shoots and leaves
Authors: Cheung Y. N. S. , Tyree M. T. , Dainty J.
Published: September 2008

Pressure–volume curves were constructed from well defined models and hypothetical shoots in which reasonable values of osmotic pressure and cell wall elastic moduli were specified for cell types of different relative volumes. The pressure–volume curves so obtained closely resembled those of real shoots and leaves. Comparing the bulk parameters obtained from analysis of the constructed pressure–volume curves with the values defined in the models allows us to examine the sources of error in their evaluation. The graphical values of the original bulk osmotic pressure and of the total volume of osmotic (symplasmic) water agreed very well with those defined; however, the osmotic pressure at incipient plasmolysis and the bulk elastic moduli estimated from the graph were generally lower than their actual values originally used in the models. We show that the apparent linear dependence of the bulk elastic modulus of sitka spruce reported by Hellkvist et al. (1974) may not reflect a similar linearity for the elastic moduli of individual cells.
Bud development in Sitka spruce. II. Cone differentiation and early development
Authors: Owens John N. , Molder Marje
Published: September 2008

Pollen-cone and seed-cone buds of Picea sitchensis (Bong.) Carr. are found as either terminal or axillary buds. Pollen cones are most likely to develop from small axillary apices on vigorous distal shoots or small terminal apices on less vigorous, proximal shoots. Seed cones are most likely to develop from large, distal axillary apices on vigorous shoots or smaller terminal apices on less vigorous shoots. All apices became mitotically active late in March, passed through a 3.5-month period of bud-scale initiation, and in mid-July became differentiated as vegetative, pollen-cone, or seed-cone apices. Potentially pollen-cone apices were smaller, had a lower mitotic frequency during bud-scale initiation, and produced fewer bud scales than apices which developed into seed-cone or vegetative buds. During bud-scale initiation all apices had a few strands of cells containing phenolic compounds in the developing pith. At the time of bud differentiation, the pith of vegetative apices accumulated more phenolic compounds and non-phenolic ergastic materials, whereas the pith of reproductive apices did not. This was followed by a marked increase in mitotic frequency in reproductive apices, resulting in changes in apical size and shape. Leaf, bract, and microsporophyll initiation began about the end of July. All microsporophylls were initiated by the end of August. Sporogenous cells developed, but meiosis did not occur before the pollen cones became dormant at the end of October. Two-thirds of the bracts were initiated by the end of August. The remaining bracts were initiated more slowly until dormancy. Ovuliferous scales were initiated for 3 months beginning in September, and megaspore mother cells appeared but did not undergo meiosis before seed cones became dormant at the end of November. There was no difference in the time of vegetative, pollen-cone, and seed-cone bud differentiation, which occurred at the end of lateral shoot elongation.
The taxonomy and genetics of Picea rubens and its relationship to Picea mariana
Authors: Gordon Alan G.
Published: September 2008

A range-wide sampling of Picea rubens Sarg. populations with a representative sampling of Picea mariana (Mill.) B.S.P. was made to investigate the variation within P. rubens and the nature and extent of hybridization between the two species. Factor analysis using 14, 21, and 24 characters, successively, indicated that the clusters of the parent species were quite discrete. Variation was found to be continuous within but not between the species, and gene flow was not more in one direction than the other. Species were found to maintain their centroides with a very low level of hybridization, and introgressive hybridization was found to be of a very limited nature.Controlled crosses indicated that the crossability of the parent species with the distantly allopatric Picea omorika ranged from 36 to 71%, while the crossability of the sympatric P. rubens × P. mariana and the reciprocal was from 1 to 3%. Other interspecific crosses were considered. Variation in the P. rubens × P. mariana F1 was substantial and sufficient to explain most of the variation observed in the occasional hybrid swarm found in nature. Backcrossing data indicate that it is not more successful than parent species crosses. Regeneration data from a soil site moisture catena for both species were evaluated to estimate the number of hybrids moving into the population relative to the parent species. These were found to be very low. A homeostatic process involving an array of both genetic and ecological barriers is proposed to explain the persistence of P. rubens in the presence of P. mariana and other selection pressures. A comparison is made of the relationships between P. glauca and P. engelmannii and that of P. rubens and P. mariana. It is concluded that the latter are not a species pair in the same sense as the former.
The in vitro induction of adventitious shoot and root apices on Narcissus (daffodil and narcissus) cultivar tissue
Authors: Seabrook Janet E. A. , Cumming Bruce G. , Dionne Leo A.
Published: September 2008

A new technique is reported here for the rapid propagation of Narcissus cultivars involving the induction of shoot and root apices from small pieces of leaf base tissue, inverted scape sections, and from ovaries, in axenic culture. Shoot and root apices were obtained on the above explants of all nine Narcissus cultivars tested. The optimal medium contained modified Murashige and Skoog (1962) inorganic salts, the organic constituents recommended by Ziv et al. (1970), and higher-than-normal growth regulator levels. Proliferating shoot apices were induced on a medium containing 4.4 × 10−5 M (10 mg/litre) 6-benzylaminopurine (BAP) and 5.3 × 10−6 M (1 mg/litre) naphthaleneacetic acid (NAA). Plantlets grew optimally if transferred to a medium containing 9.0 × 10−6 M (2 mg/litre) BAP and 2.0 × 10−7 M (2 mg/litre) NAA. The induction of roots on plantlets grown in vitro required a half-strength salt and sucrose solution without growth regulators.In 5 months, 2620 plantlets were produced from two leaf base explants. This technique is considerably more efficient than any known conventional methods of propagating Narcissus.Root apices were optimally produced on a medium containing 2.0 × 10−6 (0.5 mg/litre) to 2.0 × 10−5 M (4 mg/litre) BAP and 1.0 × 10−4 (20 mg/litre) to 2.0 × 10−5 (4 mg/litre) NAA. Callus was induced on leaf base explants, inverted scape sections, and on ovaries; the ovary expiants required the highest levels of auxin for the induction of callus and were most responsive. Thus, the levels of growth regulators required to induce a response in vitro are higher than so far reported for plants that have been propagated by tissue culture.Although the levels of various growth regulators used were found to be important in obtaining apices, the relative ratio of cytokinin to auxin was also found to be critical. Although considerable differences in clonal responsiveness were noted, cultures were obtained from all nine Narcissus cultivars tested.The induction of adventitious meristems of leaf base explants is a particularly promising method for the propagation of virus-free material and for the rapid propagation of valuable horticultural material.
Ultrastructure of conidium ontogeny in Phoma pomorum, Microsphaeropsis olivaceum, and Coniothyrium fuckelii
Authors: Jones John P.
Published: September 2008

The techniques of electron microscopy have been used to elucidate the details of conidium ontogeny in Phoma pomorum, Microsphaeropsis olivaceum, and Coniothyrium fuckelii. All three of these organisms were shown to be phialidic. The pyenidia of these organisms contained an electron-dense matrix, which in nature, probably functions as an aid to spore dispersal. In Phoma pomorum it was possible to trace conidia to their originating conidiophore through this matrix.
Bourgeonnement in vitro a partir d'épiderme séparé de feuille de Bryophyllum Daigremontianum (Crassulacées)
Authors: Bigot C.
Published: September 2008

The lower epidermis from leaves of Bryophyllum Daigremontianum Berger has been mechanically separated and cultured in liquid or solid medium; cytokinin and auxin in combination have been necessary to obtain a lamellar callus, with the Murashige and Skoog's macroelements being more efficient than White's, Knop's, or Lin and Staba's. Numerous buds have been initiated after 3 or 4 weeks, especially with naphthaleneacetic acid (1 mg/litre) in combination with 6-benzylaminopurine (0.2 mg/litre). The best results for bud formation have been obtained with the epidermis of the first and second well developed leaves. The buds, rooted in vitro, developed into normal plants. The histological study has showed that the callus was originated only from the banal epidermal cells. The stomatic cells have not been activated and died. The other tissues of the leaf have never produced any bud in the same culture conditions; then, as for other species, the epidermis has a greater ability to initiate a budding programme.
A new short chemical dehydration method for light microscopy preparations of plant material
Authors: Postek M. T. , Tucker S. C.
Published: September 2008

Complete dehydration of plant material can be accomplished in one step for plastic-embedded samples by immersal in 2,2-dimethoxypropane (DMP). This chemical reacts with any water present to form methanol and acetone. It can be used in combination with a number of easily prepared fixatives, including 10% paraformaldehyde. paraformaldehyde–glutaraldehyde, and formalin – acetic acid – alcohol (FAA). The fixation image after use of DMP is not visibly different from that of other dehydrating procedures presently in common use.
A study of peroxidase synthesis by means of double labelling and affinity chromatography
Authors: Huystee R. B. van
Published: September 2008

Peanut cells in suspension culture were incubated with [3H]leucine and [14C]5-aminolevulinic acid for 16 h. The cells were broken and extracted with a neutral buffer and a high-salt solution. Subsequently, the isolated fractions were passed through a Concanavaline A Sepharose column. It was observed that not all of the peroxidase (EC 1.11.1.7) activity was retained on the affinity column. However, the retained fraction, particularly that obtained from the high-salt extract, showed a single anionic protein with an Rf of 0.12 and with peroxidase activity. Moreover this fraction and protein has a high 14C/3H ratio (0.8) compared with the other fractions. The low specific radioactivity of this protein and its ionic bonding suggest that it may exist as a pool in the cell wall.
Studies in the brown alga Ectocarpus in culture: ultrastructural localization of enzymic activities
Authors: Oliveira Luis , Bisalputra Thana
Published: September 2008

The localization of enzymic activities (catalase. peroxidase, adenosinetriphosphatase) in vegetative cells of Ectocarpus sporophytes was carried out at the ultrastructural level.Catalase (EC 1.11.1.6) was only found in organelles recognizable as microbodies. Peroxidase (EC 1.11.1.7) was present in the cell wall, but the deposition of reaction product was also observed in the perinuclear space, endoplasmic reticulum, dictyosomes, and paramural space. Adenosinetriphosphatase (ATPase) (EC 3.6.1.3) was found associated with mitochondria, thylakoids, and the plasma membrane.
The effect of nitrate on early seedling growth in Zea mays
Authors: Srivastava H. S. , Oaks A. , Bakyta I. L.
Published: September 2008

During early seedling growth in maize, there is an initial lag before an increase in embryo nitrogen is seen, a period of rapid nitrogen increase, and finally a period of relatively minor change. Additions of NO3− to this system do not alter the nitrogen content of the seedlings during the phase of nitrogen increase. They do, however, extend this phase and this results in higher protein and alcohol-soluble nitrogen by day 6. NO3− additions have no effect on the loss of nitrogen from the endosperm. NO3− additions have a minor stimulatory effect on seed germination.The primary leaf also showed three phases of protein increase. Additions of NO3− lengthened the period of rapid protein increase, resulting in a higher level of leaf protein.The steady-state level, or inducible level, of nitrate reductase in the primary leaf is low initially, reaches a peak 7–8 days after sowing, and then declines. The results suggest that NO3− has little effect on the endogenous synthesis of nitrogenous compounds in the embryo at a time when amino acids are supplied by the endosperm.
Two new species of the genus Octospora
Authors: Khare K. B.
Published: September 2008

Two herbarium specimens, Sydow's exsiccatus, Mycotheca marchica 882 on soil, labelled as Leucoloina hedwigii Fuckel (Farlow Herbarium, Harvard University, U.S.A.), and Moravec's specimen of Octospora wrightii (Berk, and Curt.) Moravec (Nat. Mus. Prague No. 770326, Czechoslovakia), were found to represent two new species of the genus Octospora Hedw. ex Gray. These are Octospora pumilata sp. nov. and O. moravecii sp. nov., respectively. Descriptions and illustrations of these new species are provided.
Mitosis and cell division in some cereal rust fungi. I. Fine structure of the interphase and premitotic nuclei
Authors: Harder D. E.
Published: September 2008

The detailed structure of the nucleus and its associated suborganelles in the rust fungi Puccinia graminis tritici, P. graminis avenue, P. recondita, and P. coronata is described. The non-mitotic nuclei in intercellular hyphae of all of the fungi examined were irregularly oval in shape and had prominent nucleoli, and except for P. recondita, heterochromatin was usually uniformly dispersed. In P. recondita, densely staining patches occurred throughout the nucleus, and this was a distinguishing feature of this species. The nuclei in monokaryotic axenic cultures of P. graminis tritici and P. coronata were larger than those in their respective dikaryotic parasitic hyphae or in a dikaryotic axenic culture of P. graminis tritici.The nucleoli varied in size and composition, depending on the physiologic condition or type of cell. In senescing cells the nucleoli occupied about 10% of the nuclear volume, while in young active cells the respective volume occupied was up to 60%. In haustoria the nucleoli were smaller in size and were composed mainly of fibrillar material. In active intercellular hyphae of all of the fungi examined the nucleoli consisted of about equal granular and fibrillar regions. There was a lighter-staining central region and similar light spaces in the fibrillar zones. These light areas were similar to the nucleoplasm in appearance and were interpreted as lacunae possibly continuous with the nucleoplasm. The rust fungal nucleoli and those of some higher plants were compared.A bipolar spindle pole body (SPB) was a regular feature of non-mitotic nuclei. The SPB consisted of two disc-like structures located some distance apart on a layer of amorphous substance. The SPB was located outside the nucleus in a depression of the nuclear envelope, usually toward one side of the nucleus. Subtending the SPB in the nucleus and joined to the SPB via a large pore in the nuclear envelope was a moderately dense region which consisted of an amorphous layer from which loose threads radiated into the nucleus. Occasionally a thread connected this region to the nucleolus.In several cells the nuclei were deformed with concomitant extrusion of the nucleoli. Nucleolar extrusion was seen in all material examined, and the process is described. Nuclear deformation and nucleolar extrusion were considered to be indicators of premitotic nuclei.
True dichotomies in seedlings of Pinus radiata
Authors: Riding Richard T.
Published: September 2008

Histological observations of bifurcating seedlings of Pinus radiata revealed that this phenomenon resulted from a dichotomy of the shoot apex into two meristems. Vascular tissue passed equally into the two branches of the dichotomy.
Verticillium wilt of chrysanthemum: quantitative relationship between increased stomatal resistance and local vascular dysfunction preceding wilt
Authors: MacHardy William E. , Busch Lloyd V. , Hall Robert
Published: September 2008

The relationship between the development of water stress and foliar symptom expression within chrysanthemum (Chrysanthemum morifolium Ramat) cuttings infected with Verticillium dahliae Kleb. was examined using relative water content (RWC), diffusive resistance to water vapor loss (stomatal resistance), and dye distribution along water-transport pathways as indicators of water stress. The RWC remained at a normal level until symptoms appeared, but stomatal resistance increased beginning about 8 days before symptoms. Dye movement along xylem elements was uniform within uninoculated checks and also within infected plants until stomatal resistances increased. Veinal dye distribution was incomplete within tissue exhibiting increased stomatal resistances, and the extent of dye interruption was closely aligned to the magnitude of resistance increase. Apparently, stomatal closure effectively prevented tissue desiccation under conditions of high, localized internal water stress, but this mechanism could not prevent tissue from becoming flaccid or wilted when water transport became so limited that water was deficient even within the large veins.
Effects of 15% CO2 on germination, germ tube elongation, and sporulation in cultures of Colletotrichum lindemuthianum
Authors: Arnold Robert M. , Rahe James E.
Published: September 2008

Germination of conidia in cultures of the beta and gamma races of Colletotrichum lindemuthianum growing on bean juice agar was delayed in 15% CO2, though the proportion of conidia that finally germinated under these conditions was similar to the proportion that germinated in cultures maintained in air. Germ tube elongation in CO2 was inhibited during the early stages of development, but vegetative growth was ultimately stimulated under these conditions. Sporulation of cultures maintained in CO2 was delayed and fewer conidia were formed than in cultures maintained in air.The results suggest that there is an interrelationship between vegetative growth and spore production. The implications of these results to previous work on the effects of 15% CO2 on the host–parasite interaction between C. lindemuthianum and Phaseolus vulgaris are discussed.
Bark beetle – fungal symbiosis. II. Fine structure of a basidiomycetous ectosymbiont of the southern pine beetle
Authors: Happ George M. , Happ Christine M. , Barras Stanley J.
Published: September 2008

A basidiomycetous yeast is a dimorphic fungal ectosymbiont associated with the southern pine beetle, Dendroctonus frontalis. Within the mycangium (a glandular integumental invagination) of the southern pine beetle, the fungus grows in a yeast-like manner, while on some media or in a plant host, it forms mycelial masses. The yeast stage has a lamellate cell wall and forms new cross walls in a manner rather similar to the basidiomycetous yeasts. Like certain ambrosial fungi (Ascoidea), the yeast stage is multinucleate. The mycelial stage, initially produced in culture and within the plant host, shows clamp connections and dolipore septa, characteristic of many Basidiomycetes, but its cell wall is not lamellate.The dolipore septa have septal pore caps and also mirror images of these caps. The septal pore caps (about 400 Å in thickness) have five layers: the two outermost (40 Å) are probably continuous with the 'unit membranes' of the endoplasmic reticulum; the middle layer is similar to the outermost; and the intervening zones (150–170 Å) are homogeneous and of intermediate electron density. The endoplasmic reticulum is both tubular and cisternal, and some portions of the membranes are associated with ribosomes. The multinucleate condition is regarded as a special adaptation for effective colonization; otherwise the ectosymbiont is consistently similar to known basidiomycetous yeasts.
Regulation of seed dormancy in Elaeagnus angustifolia by endogenous growth substances
Authors: Hamilton D. F. , Carpenter P. L.
Published: September 2008

A coumarin-like germination inhibitor was found in the endocarp, testa, and embryo of dormant seed of Elaeagnus angustifolia L. Activity of the inhibitor did not decrease during 90 days at 5 °C. However, evidence showed that the inhibiting substance may be physiologically effective in preventing germination of dormant seed. A growth-promoting substance formed during low-temperature afterripening apparently reverses the effect of the endogenous inhibitor.
X-ray diffraction evidence for decreased lipid fluidity in senescent membranes from cotyledons
Authors: McKersie B. D. , Thompson J. E. , Brandon J. K.
Published: September 2008

Smooth microsomal membranes were isolated from bean cotyledons at various intervals after planting. Wide-angle x-ray diffraction patterns were recorded at room temperature from oriented specimens of the membranes. Patterns for membranes from 2-day-old cotyledons featured a broad lipid reflection centered about a Bragg spacing of 4.6 Å. This diffraction band derives from the apolar hydrocarbon chains of the membrane phospholipid, and its diffuse nature indicates that these hydrocarbons are in a disordered liquid–crystalline state. By day 4 in the germination sequence a faint sharp band superimposed on the broad lipid reflection was discernable at a Bragg spacing of 4.15 Å. This sharp reflection represents lipid in an ordered, crystalline state and derives from a close hexagonal packing of the hydrocarbon chains. During the later stages of germination the 4.15-Å reflection intensified to the point of becoming very pronounced in patterns for membranes from 9-day-old cotyledons. These patterns also displayed a sharp but weaker reflection at 3.75 Å, which derives from an orthorhombic packing of the hydrocarbon chains in crystalline lipid. By 9 days of age the cotyledons were extensively senescent and beginning to abscise.The data indicate that senescence of membranes involves a phase change whereby the proportion of crystalline to liquid– crystalline lipid progressively increases. This changed physical state of the lipid represents a substantial decrease in membrane fluidity and may well contribute to loss of membrane function in senescing membranes.
Cercospora rodmanii, a new pathogen of water hyacinth with biological control potential
Authors: Conway Kenneth E.
Published: September 2008

A species of Cercospora was isolated from declining water hyacinths in the Rodman Reservoir in Florida. Differences between this isolate and a previously reported C. piaropi from water hyacinths and other morphologically similar species of Cercospora from other hosts warranted the establishment of a new species, C. rodmanii. Field evaluations of C. rodmanii indicate that it has biological-control potential for water hyacinth.
Light and electron microscopic observations of conidiogenesis in Peziza quelepidotia
Authors: O'Donnell K. L. , Fields W. G. , Hooper G. R.
Published: September 2008

Conidium ontogeny of the botryose solitary blastospores of Peziza quelepidotia Korf and O'Donnell was followed by time-lapse photomicrography using differential interference-contrast illumination in an inexpensive, commercially available, slide culture chamber. This chamber has several advantages over those previously described. Subsequent to time-lapse photomicrography, techniques are described for viewing these identical conidiophores in all stages of development in the scanning electron microscope. Transmission electron microscopic observations were conducted to fully characterize conidiogenesis and to unequivocally determine its location in hyphomycete classification schemes. This imperfect state, which belongs to Hughes' conidiogenetic section 1B, bears determinate retrogressive conidiogenous cells and single holoblastic conidia with multiple synchronous conidiogenous loci. However, unlike other members of the Botryoblastosporae, the conidia are not borne on well differentiated swollen conidiogenous cells (i.e., ampullae). Ultrastructural observations were made on the spatial relationship between the conidial state and ascogonia and on germinating conidia.