bluuebunny/crossref_metadata_2025 huggingface dataset:
Éléments pour une approche morphométrique de la croissance végétale et de la floraison : le cas d'espèces tropicales du modèle de Leeuwenberg
Authors: Lauri P. E. , Terouanne E.
Published: December 2007

A quantitative description of primary growth from the apical meristem activity is proposed for four tropical plants: Alstonia vieillardii var. vieillardii (Apocynaceae), Miconia ciliata (Melastomaceae), Ricinus communis (Euphorbiaceae), and Solanum rugosum (Solanaceae). The development of these four plants corresponds to Leeuwenberg's model. Three parameters were measured at different stages of plant growth: leaf surface, length of the underlying internode, and the surface of the internode section. Two other parameters were derived from these three: parameter T, which summarizes the first three parameters and corresponds to the overall dimension of the leaf–internode system, and parameter D, showing the differential evolution of the leaf surface and the corresponding axial volume. The higher the D value, the higher the predominance shown by the twig over the leaf component. This phenomenon is named axialization. The reciprocal situation is called foliarization. For parameter T, the observed variations are present in all four species and showed an increase followed by a decrease in dimensions during the growth process. From the evolution of parameter D, two processses can be recognized. In A. vieillardii var. vieillardii and Solanum rugosum, the amplitude of variation is wide and can be compared with that of parameter T. In M. ciliata and R. communis, the amplitude of variation is significantly reduced. A link can be established between this morphometric evolution and flowering. The results obtained for these four species are compared with those obtained by other researchers and bring new elements to the study of the relationship between the vegetative evolution of the plant and its flowering. Key words: architecture, morphometry, Leeuwenberg's model, ontogeny. [Journal translation]
Effets de l'adjonction de KCl ou de CaCl2 sur la tolérance au NaCl chez deux cultivars de triticale (Clercal et Beagle)
Authors: Haddad Souheil , Coudret Alain
Published: December 2007

The effects of salinity on growth along with water and ion relations were studied on two cultivars of triticale (Clercal and Beagle) after 21 days of growth under controlled conditions in nutrient solutions with or without 150 mM NaCl, and on nutrient solutions with 150 mM NaCl + 20 mM KCl or 150 mM NaCl + 20 mM CaCl2. Growth was strongly affected by an increased NaCl concentration in the culture medium, causing a water deficit linked to a drop in water (ψ) and osmotic (π) potentials, followed by an accumulation of Na+ and a reduction of K+ in the aboveground part of the triticales. Addition of KCl or CaCl2 to NaCl-containing media improved NaCl tolerance of the plant: growth increased more than 30%, hydration of tissues improved, and K+ uptake was normal, as seen by an increased K+/Na+ selectivity ratio in the aboveground parts. The two cultivars did not show the same degree of tolerance on these media. The protection afforded by KCl or CaCl2 in the NaCl-containing media was more significant for 'Clercal' than for 'Beagle'. Moreover, it seems that in presence of KCl or CaCl2, the improved K+ uptake was greater in 'Clercal' than in 'Beagle'. It is therefore possible that 'Beagle' requires less K+ than 'Clercal' for normal cell functioning. It is suggested that the K+/Na+ selectivity ratio is critical for salinity tolerance in the triticales. Key words: NaCl, KCl, and CaCl2 tolerance, growth, water, relationships, osmotic adjustment, K+–Na+ selectivity, 'Clercal', 'Beagle', triticale.
Nutrient release from epiphytic bryophytes in tropical montane rain forest (Guadeloupe)
Authors: Coxson Darwyn S.
Published: December 2007

Drought exposure in the upper canopy of tropical montane rain forest (Guadeloupe) leads to the pulsed release of solutes from epiphytic bryophytes within the cloud forest canopy. This efflux, leached from newly rewetted mosses and hepatics, was greatest for ions normally held within intracellular pools. Estimates of solute efflux from stem segments of canopy bryophytes reached 80.1 kg ha−1 year−1 for K, 1.4 kg ha−1 year−1 for P, and 11.8 kg hal−1 year−1 for N during experimental rewetting episodes. Estimates of solute efflux from intact bryophyte mats during field rewetting episodes were smaller, only 28.7 kg ha−1 year−1 for K and 0.2 kg ha−1 year−1 for P. The difference between these measurements is thought to reflect internal recycling of released ions within the canopy bryophyte mats during rewetting episodes. Nonetheless, nutrient loss to throughflow solution represents a significant portion of the standing nutrient capital held within canopy bryophyte mats. By releasing previously sequestered nutrients, bryophyte communities not only provide access to resource pools that would otherwise be inaccessible, but may stimulate the further transformation of nutrients as leaf epiphyll and decomposer communities respond to enriched throughflow solution pulses. These data suggest that recycling of nutrients between members of the standing biomass in tropical montane rain forest is not a steady state process, as often envisaged, but rather may be highly episodic in nature. Key words: tropical montane rain forest, bryophytes, epiphytes, nutrient cycling, throughflow.
Structure of ectomycorrhizae formed by Wilcoxina mikolae var. mikolae with Picea mariana and Betula alleghaniensis
Authors: Scales Pamela F. , Peterson R. L.
Published: December 2007

The structure of ectomycorrhizae synthesized between the E-strain fungus, Wilcoxina mikolae var. mikolae and two tree species, Picea mariana and Betula alleghaniensis, was characterized by light microscopy and scanning electron microscopy. For both mycorrhizal types, mantle formation was visible on lateral roots within 10 days of inoculation. Picea mariana ectomycorrhizae had a very thin mantle whereas B. alleghaniensis ectomycorrhizae had a mantle consisting of several layers. For both mycorrhizal types, the innermost mantle hyphae were embedded in a considerable amount of mucigel on the root surface. A well-developed Hartig net with labyrinthic growth occurred in both types of mycorrhizae. Betula alleghaniensis ectomycorrhizae had a paraepidermal Hartig net, and the root epidermal cells were radially elongate at an oblique angle. The Hartig net of P. mariana ectomycorrhizae penetrated the epidermis and all layers of the cortex. The cytoplasmic density of the intercellular hyphae was greatest towards the root apex. Ectomycorrhizal associations formed by E-strain fungi were similar to ectomycorrhizae formed by other fungi. Key words: E-strain, ectomycorrhizae, Wilcoxina, Picea, Betula, Hartig net.
Effects of drought stress on hydraulic architecture of seedlings from five populations of green ash
Authors: Shumway Durland L. , Steiner Kim C. , Abrams Marc D.
Published: December 2007

Two-year-old seedlings of green ash, Fraxinus pennsylvanica Marsh., representing five native populations from an east to west precipitation gradient, were grown under contrasting moisture regimes in the greenhouse. At midsummer and the end of the growing season, leaf areas, earlywood and latewood transverse areas, and several structural attributes of the xylem hydraulic system were compared between well-watered and drought-stressed seedlings. Xylem hydraulic capacity was essentially fixed by midsummer. Drought significantly reduced both earlywood and latewood production but had no significant effect on potentially functional xylem area (Apf) or flow velocity (v). The principal effect of drought on hydraulic architecture was a significant reduction in leaf area and therefore the ratios of potentially functional xylem area to unit leaf area (Apf to A1) and leaf specific conductivity (LSC). In contrast, populations differed significantly in all measured parameters, especially under drought conditions. Path analysis of LSC and its component variables revealed that treatment differences in LSC arose primarily through differences in A1; contributions from variation in Apf and especially flow velocity were relatively minor. In contrast, population variation in LSC could be attributed in roughly equal measure to variation in Apf and A1, and to a lesser degree to variation in flow velocity. The covariance between A1 and Apf was important for both treatment and population variation in LSC, suggesting a fundamental physiological linkage between these two aspects of plant hydraulic architecture. Among populations, high flow velocity tended to be associated with low Apf to A1 values, thereby minimizing population differences in the composite character LSC. Populations differed significantly in all attributes studied, in one environment or another, but those at either end of the precipitation gradient did not differ in several presumably important structural attributes. Although plant hydraulic architecture is genetically controlled and variable in green ash seedlings, its adaptive significance cannot be considered in isolation from other factors that control plant response to water stress. Key words: leaf specific conductivity, ecotypic variation, xylem structure.
Characterization of Canadian and European Melanconium from some Alnus species by morphological, cultural, and biochemical studies
Authors: Sieber T. N. , Sieber-Canavesi F. , Petrini O. , Ekramoddoullah A. K. M. , Dorworth C. E.
Published: December 2007

Melanconium apiocarpum (anamorph of Melanconis alni), Melanconium marginale (anamorph of Melanconis marginalis), and other Melanconium species isolated from healthy and diseased tissues of Alnus species in Canada, England, and Switzerland were compared by means of morphological, cultural, and biochemical techniques, and the results were analyzed by numerical methods. No differences were recorded between symptomless endophytes and disease syndrome associated isolates of M. apiocarpum, although European and Canadian isolates could be consistently and clearly differentiated by protein profiles and cellulose utilization patterns. On the basis of cultural and biochemical characters as well as conidia morphology, M. apiocarpum and M. marginale are distinct species. Two intraspecific groups of M. marginale, particular to separate Alnus species, were identified. Melanconium isolates from Fagus sylvatica and Quercus robur are clearly distinct from those on Alnus. Key words: Melanconium, Melanconis, Alnus, numerical taxonomy.
Enhanced peroxidase activity associated with the hypersensitive response of Solanum dulcamara to the gall mite Aceria cladophthirus (Acari: Eriophyoidea)
Authors: Bronner R. , Westphal E. , Dreger F.
Published: December 2007

Peroxidase activity and its electrophoretic pattern were studied in resistant Solanum dulcamara leaves following infestation by the gall mite Aceria cladophthirus. Total peroxidase activity increased in infested leaves and was related to enhancement of three major peroxidase isozymes. The highest activity was found for the intercellular peroxidases. The extraction procedures used suggest that these peroxidases are pathogenesis-related proteins. These results are discussed with reference to the lack of lignin barrier around the mite-induced necrotic local lesions. Key words: Aceria cladophthirus, gall mite, Solanum dulcamara, resistant plant, pathogenesis-related proteins, peroxidases isozymes.
Effet de l'irradiation des semences d'orge (Hordeum vulgare) sur la croissance des jeunes plantules et la résistance au Drechslera teres
Authors: Arabi M. I. , Barrault G. , Sarrafi A. , Albertini L.
Published: December 2007

Barley seeds of two cultivars (Smash and Thibaut) and one line (74-F-6) with water contents adjusted between 12.8 and 13.3%, were irradiated with various doses (1–160 Gy) of 60Co γ rays. Doses of 1–40 Gy favored an increased length of the first leaf. In general, doses of 15 and 20 Gy decreased barley susceptibility to Drechslera teres f. maculata by 25 and 21%, respectively. This reduction was a function of the line or cultivar used. The best response was obtained with cv. Smash. Seedling growth stimulation and host susceptibility to D. teres were significantly correlated (r = −0.68). The stimulatory effect of γ rays on growth could be used at low levels, to provide adequate field resistance to net blotch caused by D. teres f. maculata. Key words: barley, Hordeum vulgare, seeds, γ ray, net blotch, Drechslera teres.
The coenological organization of ectomycorrhizal macrofungi in the Laurentide Mountains of Quebec
Authors: Villeneuve Normand , Grandtner Miroslav M. , Fortin J. André
Published: December 2007

Ectomycorrhizal macrofungus communities were classified across a sequence of four forest associations in the Laurentide Mountains. Cluster analysis was used to delimit two types of coenological units: grouping and sociological group. Three macrofungal groupings and two subgroupings, which vary with physiognomic and floristic–edaphic parameters of the forest sites, were delimited. Each of these grouping units is characterized by one of the six delimited sociological groups of fungi that are consecutively replaced following changes in latitude and altitude. When considering the similarity of species composition, Laurentide groupings appear to be isolated from other macrofungal assemblages in North American temperate forests and mainly affected by geographic partitioning of sites and by the physiognomy and type of forest vegetation within a given phytoclimatic region. As seen by the respective richness at the family level, Eurasian and Laurentide communities show similar patterns of zonal distribution, mainly owing to the role of climatic factors. A numerical analysis supported the hypothesis that the edaphic environment, as well as the vascular vegetation, might exert a significant influence on the delimitation and distribution of ectomycorrhizal communities. The interdependence of ectomycorrhizal communities and phytocoenoses at the ecosystem level is discussed. Key words: cluster analysis, community, ectomycorrhiza, macrofungus, macromycete, mycocoenology.
Gall development and fine structure of the nutritive cells of Myopites blotii (Diptera, Tephritidae) on Inula salicina
Authors: Rohfritsch Odette , Arnold-Rinehart Hanna
Published: December 2007

The tephritid fly Myopites blotii attacks the flower head of Inula salicina at the outset of anthesis. Their larvae tunnel through tubular florets, achenes, and vertically through the swollen, densely vascularized floral receptacle. The goal of the mining larvae is the large vascular bundles at the base of the bracts. The tunneling larvae cut a number of vascular bundles irrigating the florets and the resulting cavity is always open to the outside. Cell walls and cell remnants are continuously agglomerated by the larvae along the entrance channel, forming a black layer. Small patches of nutritive cells appear near severed vascular bundles that end in the larval cavity. The nutritive cells are activated to a high level of RNA and proteosynthesis. The cells have a dense cytoplasm and a large lobed nucleus with a large nucleolus. The long, flexuous plastids form a perinuclear crown. Numerous mitochondria and peroxisomes attest to intense respiration in these cells. The nutritive cells provide proteins and nucleoproteins to the larvae that also feed directly on the vascular bundles ending in the larval cavities. The more sedentary, nearly mature larvae concentrate their feeding activity toward the bottom of the larval cavity where a nutritive layer differentiates. A sclerenchyma layer forms that isolates the larval cavity from the vascular bundles of the floral receptacle. Key words: gall, nutritive tissue, floral receptacle, Tephritidae, Inuleae, Asteraceae.
Survival characteristics of buried seeds 10 years after the eruption of the Usu volcano in northen Japan
Authors: Tsuyuzaki Shiro
Published: December 2007

In the crater basin of the Usu volcano, where the vegetation has almost completely been destroyed by 1977–1978 eruptions, a study was conducted in 1987 to determine the survival characteristics of buried seed populations. A total of 17 618 seeds were extracted from six 25-L former topsoil blocks by a flotation test. Data showed that even after 10 years burial by 65–140 cm volcanic deposists, 16.6% of the seeds, representing 25 species, were viable. There were few predators in the former topsoil below the thick volcanic deposits. Seed volume of most species was less than 2.0 mm3 and smaller seeds had a greater rate of survival than larger seeds. Seed survival rates of Poa annua, Rumex obtusifolius, Alopecurus aequalis var. amurensis, and Viola grypoceras were positively correlated with the thickness of volcanic deposits, suggesting that the most important factor for seed survival is stable soil temperature with little diurnal fluctuations. Absence of light may be an important variable in seed survival, but this factor did not sufficiently explain survival under the thick volcanic deposits. Key words: buried seed, burial depth, seed size, seed survival, soil temperature, volcano Usu.
Characterization and plant regeneration of cell suspension cultures of Lycopersicon chilense
Authors: Greer Ann Francine , Tabaeizadeh Zohreh
Published: December 2007

To produce calli for the establishment of a cell suspension, leaf, stem, and petiole explants of Lycopersicon chilense Dun., grown in vitro and in the soil, were cultured on media containing 15 different combinations of benzylaminopurine, kinetin, and indole acetic acid. Among the three types of tissues, leaf explants showed the best response. Cell suspension cultures of L. chilense were established from leaf callus derived from soil grown plants using Murashige and Skoog's medium supplemented with casein hydrolysate (250 mg/L), coconut water (5%), and 2,4-dichlorophenoxyacetic acid (2 mg/L). Once established, cell suspensions showed a rapid growth rate with no marked lag phase. Shooting via organogenesis occurred from callus derived from cell suspensions on medium containing 2 mg/L benzylaminopurine. Regenerated plants had the same morphology as the original plants. Key words: Lycopersicon chilense, tomato, tissue culture, cell suspensions, organogenesis, plant regeneration.
Allozyme variation in the Polygonum lapathifolium complex
Authors: Consaul Laurie L. , Warwick Suzanne I. , McNeill John
Published: December 2007

The Polygonum lapathifolium complex consists of populations that are widely distributed in the Northern Hemisphere and that have been classified at different taxonomic levels. Allozyme data were used to test the current North American taxonomic status of members of the complex (including P. lapathifolium var. lapathifolium, P. lapathifolium var. salicifolium, and P. scabrum) and to verify diploidy in the P. lapathifolium complex and polyploid origins of the morphologically similar P. persicaria and P. pensylvanicum. Of the 15 enzyme systems surveyed in 50 populations of the complex, only 3 of the 23 loci (Acon, Lap, and Skdh) were polymorphic in the North American populations and a total of 6 loci in European populations. Fifteen multilocus genotypes were evident in the complex. Four genotypes (all with Lap-10.67 were exclusive to North American populations of P. lapathifolium, providing support for a North American element of the complex. Nine genotypes (all with Lap-10.63) were found in North American and European populations of P. scabrum, all European populations of the P. lapathifolium complex, and three populations of North American P. lapathifolium var. lapathifolium. Lap-10.67 was also found in the native tetraploid P. pensylvanicum, whereas Lap-10.63 was found in the introduced tetraploid P. persicaria. Genetic distances among populations did not support the current taxonomic divisions within the complex, nor did it support separate species status of P. scabrum. Allozyme data provided support for the allotetraploid origins of P. pensylvanicum and P. persicaria, with members of the P. lapathifolium complex as one of the parents of each. Key words: Polygonum lapathifolium, Polygonum scabrum, Polygonum pensylvanicum, Polygonum persicaria, allozymes.
Early events in living epidermal cells of cowpea and broad bean during infection with basidiospores of the cowpea rust fungus
Authors: Xu Haixin , Mendgen Kurt
Published: December 2007

The infection process of basidiospores of the cowpea rust fungus (Uromyces vignae) was studied on living host (Vigna sinensis) and nonhost (Vicia faba) leaves using light microscopy with differential interference contrast optics. During the first 8 h, fungal development was similar on host and on nonhost leaves. Penetration and production of intraepidermal vesicles occurred in nonhost cells 4 h earlier than in host cells. Penetration frequency was also higher in nonhost leaves. These results suggest that the cuticle of the cowpea plant delays basidiospore infection. Both host and nonhost cells produced cytoplasmic aggregates during appressorium formation and again, a few hours later, during penetration of the epidermal cell wall. Cytoplasmic aggregates were also observed in cells adjacent to a collapsing cell. Papillae were observed at most infection sites in both host and nonhost cells. The nuclei of infected cells migrated towards the penetration site in both plant–pathogen combinations. Nuclear size increased considerably only in the nonhost epidermis and decreased again markedly after cell collapse. In the nonhost cells, three types of defence reactions occurred during or after formation of the intraepidermal vesicle. First, following the halt of cytoplasmic streaming, the cytoplasm of the invaded cell either contracted or disintegrated into granules. Alternatively, the cytoplasm continued streaming but darkly pigmented material encased the fungal infection structure. Key words: basidiospore, broad bean (Vicia faba), cowpea (Vigna sinensis), cowpea rust fungus (Uromyces vignae), hypersensitivity, nonhost resistance.
Bud exudate composition of Populus tremuloides
Authors: English S. , Greenaway W. , Whatley F. R.
Published: December 2007

Gas chromatography – mass spectrometry analysis of the bud exudate of seven specimens of Populus tremuloides (section Leuce) revealed a different chemical composition from that previously observed for poplars of sections Aigeiros and Tacamahaca. The bud exudate consists of three principal groups of compounds; benzoic and phenylpropenoic acids and their esters, the flavanones isosakuranetin and sakuranetin and their corresponding chalcones, and hydrocarbons. The flavonoids characteristic of section Aigeiros and section Tacamahaca poplars were found to be either missing, as in the case of flavanonols and dihydrochalcones, or present in very small amounts. The seven specimens of P. tremuloides analysed were classified into three categories depending on the relative proportions of these three groups of compounds present in their bud exudate, and the exudate composition was compared with that of four specimens of Populus grandidentata analysed. Key words: Populus tremuloides, bud exudate, gas chromatography – mass spectrometry.
Basidiocarp development of the cyphelloid gasteroid aquatic basidiomycetes Halocyphina villosa and Limnoperdon incarnatum
Authors: Nakagiri Akira , Ito Tadayoshi
Published: December 2007

Basidiocarp structure and development in the aquatic basidiomycetes Halocyphina villosa and Limnoperdon incarnatum were observed under a scanning electron microscope. Halocyphina villosa produces completely closed gasteroid basidiocarps at the early developmental stage while it shows cyphelloid hymenium distribution and ballistosporic basidiospore formation. Alternatively, the basidiocarp of L. incarnatum is cyphelloid at the initial stage but becomes closed at maturity. Basidia and basidiospores are gasteroid and nonballistosporic and are distributed on a loosely formed hymenium. These observations suggest that a cyphelloid hymenomycete and a gasteromycete, terrestrial Basidiomycetes by origin, have evolved into the two aquatic species by now possessing similar closed basidiocarps adapted to aquatic habitats. Key words: Halocyphina villosa, Limnoperdon incarnatum, aquatic basidiomycete, gasteroid basidiocarp.
On the occurrence of hypersaline sediments in James Bay coastal marshes
Authors: Price Jonathan S.
Published: December 2007

Measurements of soil salinity, soil moisture, and specific yield, along with depth to the water table, explain the occurrence of a band of hypersaline sediments, ubiquitous along James Bay coastal marshes, that profoundly affects vegetation development. The salinity of the hypersaline zone ranges from 8 g/kg Cl in a southern James Bay marsh, to 28 g/kg in the north, nearly an order of magnitude more than local sediments outside this zone. This common, yet previously unexplained, feature restricts the vegetation development to salt-tolerant species such as Salicornia maritima, Puccinellia phryganodes, and Triglochlin maritimum. The hypersaline zone is rarely inundated by tides, but frequent inundation of the seaward zone maintains a high water table there, with soil salinity, hence vegetation patterns that reflect the ambient tidewater salinity. At sites inland of the hypersaline band the development of an organic layer with a high moisture content supplied by meteoric water and high specific yield maintains relatively fresh water near the surface, imposing minimal salinity restrictions to vegetation. Intermediate to these zones of high water table is the hypersaline band, which has no organic layer and whose surface is not wetted by tides. Its depressed water table causes flow convergence, and the only water sink is through evaporation, which concentrates the salt imported in groundwater. Key words: James Bay, marsh, salinity, hydrology, vegetation.
Variation in ribosomal DNA among isolates of the mycorrhizal fungus Cenococcum geophilum
Authors: Lobuglio Katherine F. , Rogers Scott O. , Wang C. J. K.
Published: December 2007

Restriction fragment length polymorphisms in ribosomal DNA were used to assess the degree of variation among 71 Cenococcum geophilum isolates of both geographically distinct and similar origins. Southern hybridizations using cloned C. geophilum ribosomal DNA indicated extensive variation among isolates, greater than has been previously reported to occur within a fungal species. Most of the polymorphisms were located within the region from the intergenic spacer through internal transcribed spacer 1. Restriction-site and length polymorphisms also occurred within the 5.8S through 26S genic region. Sixteen size categories of length mutations, six restriction-site additions, and four restriction-site deletions were observed compared with a reference isolate. HindIII-digested DNAs displayed fewer polymorphisms in the mitochondrial 24S ribosomal RNA gene (and flanking regions) than in nuclear ribosomal DNA. UPGMA cluster analysis of shared nuclear ribosomal DNA patterns indicated 32 unique phenotypes and grouped C. geophilum isolates into a broad range of clusters ranging from 100 to 44% similarity. The amount of ribosomal DNA variation demonstrated in this study indicates that C. geophilum is either an extremely heterogenous species or a fungal complex representing a broader taxonomic rank than presently considered. Key words: Cenococcum geophilum, ribosomal DNA, restriction polymorphisms.
A revision of the genus Trichoderma. II. Infrageneric classification
Authors: Bissett John
Published: December 2007

The genus Trichoderma Pers.:Fr. is defined to include anamorphs of Hypocrea, previously placed in Gliocladium and Verticillium, having elongate phialides and irregularly branched conidiophores. A sectional classification is proposed for Trichoderma recognizing the following five sections: section Trichoderma, section Longibrachiatum Bissett, section Saturnisporum Doi et al., section Pachybasium (Sacc.) stat.nov., and section Hypocreanum sect.nov. Trichoderma lactea sp.nov. is described, typifying section Hypocreanum. The species in section Trichoderma have narrow and flexuous conidiophores and branches, with branches and phialides uncrowded, frequently paired, and seldom with more than three elements in a whorl. Section Pachybasium includes species with highly ramified conidiophores that are often aggregated into compact fascicles or pustules and with relatively short, broad branches bearing inflated phialides in crowded verticils. Section Hypocreanum accommodates Trichoderma anamorphs of Hypocrea that have effuse conidiation, sparingly branched conidiophores, and cylindrical to subulate phialides. The placement of existing Trichoderma species, species aggregates, and some anamorphs of Hypocrea in the five sections is discussed, and a key is provided to differentiate the sections of Trichoderma. Key words: Trichoderma, sectional classification, Hypocrea, Gliocladium.
A revision of the genus Trichoderma. III. Section Pachybasium
Authors: Bissett John
Published: December 2007

Twenty species assigned to Trichoderma section Pachybasium (Sacc.) Bissett are described and differentiated on the basis of conidiophore and conidium morphology. Included in section Pachybasium are T. hamatum, T. polysporum, T. piluliferum, T. harzianum, and T. virens that were already recognized in Trichoderma; T. flavofuscum comb.nov. transferred from Gliocladium; the anamorphs of Hypocrea gelatinosa, H. semiorbis, and two unnamed Hypocrea species; and 10 new species segregated from the T. hamatum species aggregate of M. A. Rifai (1969. Mycol. Pap. 116: 1–56). The new species Trichoderma crassum, T. croceum, T. fasciculatum, T. fertile, T. longipilis, T. minutisporum, T. oblongisporum, T. pubescens, T. spirale, T. strictipilis, T. strigosum, and T. tomentosum are proposed. Keys are provided to distinguish the 20 known species in section Pachybasium. Key words: Trichoderma section Pachybasium, Hypocrea, taxonomy.
A revision of the genus Trichoderma. IV. Additional notes on section Longibrachiatum
Authors: Bissett John
Published: December 2007

Trichoderma parceramosum nom.nov. replaces the illegitimate name Trichoderma atroviride Bissett, a later homonym of T. atroviride Karsten. The Trichoderma anamorph of Hypocrea schweinitzii (Fr.:Fr.) Sacc. is described and differentiated from the four other species in section Longibrachiatum.Key words: Trichoderma section Longibrachiatum, taxonomy.
Relationships among native and introduced North American species of Hordeum, based on chloroplast DNA restriction-site variation
Authors: Baum Bernard R. , Bailey L. Grant
Published: December 2007

Restriction-site analysis of chloroplast DNA was carried out on a total of 13 North American species of Hordeum, 7 native and 6 introduced. Sites associated with polymorphic banding patterns were omitted so that only invariant sites within species were used in the analyses. A number of taxa whose species status is in dispute can indeed be supported at species rank, i.e., H. brachyantherum, H. californicum, H. pusillum, H. intercedens, H. marinum, and H. geniculatum. The maternal progenitor of H. arizonicum is H. pusillum, and this is further discussed in light of other possibilities. Both phenetic and cladistic analyses indicate a tripartite relationship whereby H. vulgare is distant from the group of H. leporinum, H. glaucum, and H. murinum and from a second group comprising the native species H. brachyantherum, H. californicum, H. arizonicum, H. jubatum, H. pusillum, H. intercedens, and H. depressum. Hordeum marinum and H. geniculatum occupy a central position in this relationship. Speculation that the putative ancient form of Hordeum resembled a H. murinum – H. geniculatum-like species is discussed. Key words: chloroplast DNA, Hordeum, phylogenetic relationships.
Influence of fungal propagules during the early stage of the time sequence of ectomycorrhizal colonization on Afzelia africana seedlings
Authors: Ba A. M. , Garbaye J. , Dexheimer J.
Published: December 2007

A sequence of ectomycorrhizal colonization was observed on lateral roots of Afzelia africana Sm. seedlings. Four ectomycorrhizal types were obtained by a baiting method. Among the four types, two were recognized as occurring first in the ectomycorrhizal colonization sequence and the others occurred later. This sequence of ectomycorrhizal colonization was interpreted as follows: initial ectomycorrhizal types were related to the presence of vegetative propagules in the soil (mycorrhizal root fragments, fragments of mycelial strands, and sclerotia) and to the ability of the hyphae from these propagules to grow and quickly colonize Afzelia root systems. The time required for mycorrhizal colonization from spores, however, would be much longer. The types of mycorrhizal symbionts that were established first did not affect subsequent mycorrhizal colonization. An ultrastructural study suggested that vegetative propagules could function either as structures for long-term survival of the fungus in the soil or as structures for immediate opportunistic root colonization. Key words: ectomycorrhizal colonization, baiting method, fungal propagules, early stage fungi, Afzelia africana.
The consequences of mixed pollination on seed set in Vaccinium corymbosum
Authors: Kloet S. P. Vander
Published: December 2007

Self pollen of Vaccinium corymbosum germinates as well as outcross (compatible) pollen from the same population and more rapidly than compatible pollen from more distant populations. When a mixture of self and compatible pollen, either from the same or incontiguous populations, is applied to the stigma, the time required for berry ripening is significantly reduced compared with compatible pollen alone, although seed set also decreases significantly. Adding compatible pollen from different pollen donors significantly increased seed set but also increased the time for berry maturation by 5 days. Self pollen in conjunction with compatible pollen resulted in a 50% loss of viable seed production and an 8% gain in berry maturation time. Self-pollination resulted in embryo abortion in V. corymbosum. Key words: pollination, Vaccinium, seed set, outcrossing.
Phenology and growth in four annual species grown in ambient and elevated CO2
Authors: Reekie E. G. , Bazzaz F. A.
Published: December 2007

The objectives of this study were (i) to test the hypothesis that changes in phenology with CO2 are a function of the effect of CO2 upon growth and (ii) to determine if CO2-induced changes in phenology can influence competitive outcome. We examined the effect of 350, 525, and 700 μL∙L−1 CO2 on Guara brachycarpa, Gailardia pulchella, Oenothera laciniata, and Lupinus texensis. Plants were grown as individuals in 150-, 500-, or 1000-mL pots and in competition in 1000-mL pots. Growth and development were monitored at twice-weekly intervals by recording the number of leaves and noting the presence or absence of stem elongation, branching, flower buds, and open flowers. Elevated CO2 affected both growth and phenology, but the direction and magnitude of effects varied with species and soil volume. Elevated CO2 did not appear to affect development through its effect on growth. Those treatments in which there were significant effects of CO2 on growth were generally different from those treatments in which CO2 affected phenology. Rather than affecting phenology by changing plant size, CO2 appeared to affect phenology by modifying the size at which plants switched from one stage to the next. The level of CO2 changed competitive outcome; the importance of Lupinus increased whereas that of Oenothera decreased with increased CO2. These changes were more closely related to the effect of CO2 on growth than its effect on phenology. Key words: time of flowering, size at flowering, competition, photoperiod, rate of development.
Photosynthetic response of geranium to elevated CO2 as affected by leaf age and time of CO2 exposure
Authors: Kelly D. W. , Hicklenton P. R. , Reekie E. G.
Published: December 2007

Geranium plants were grown from seed in chambers maintained at 350 or 1000 μL∙L−1 CO2. Phtopsynthesis as affected by leaf age and by leaf position was determined. Elevated CO2 enhanced photosynthesis to the greatest extent in middle-aged leaves; very young leaves exhibited little enhancement, and net photosynthesis in the oldest leaves was depressed by elevated CO2. Temporary increases in net photosynthesis (relative to leaves developed at high CO2) resulted when young leaves grown at 350 μL∙L−1 CO2 were switched to 1000 μL∙L−1 CO2. Leaves switched later in development exhibited permanent enhancement. Middle-aged leaves exhibited a temporary depression followed by permanent enhancement. Leaves developed at high CO2 and switched to low CO2 did not exhibit any photosynthetic depression relative to plants grown continuously at low CO2. Similarly, leaves developed at low CO2, switched to high CO2 for various lengths of time, and returned to low CO2 showed no photosynthetic depression. Leaves developed at low CO2 and switched to high CO2 exhibited increases in specific leaf weight and leaf thickness. The increase in leaf thickness was proportional to length of time spent at high CO2. High CO2 depressed the rate at which stomata developed but did not affect final stomatal density. Results suggest that photosynthesis at low CO2 was limited by CO2 regardless of developmental environment, whereas photosynthesis at high CO2 was limited by the developmental characteristics of the leaf. Further, both biochemical and structural modifications appear to be involved in this response. Because of the very different responses of young versus old leaves, future studies should be careful to consider leaf age in assessing response to elevated CO2. Key words: carbon dioxide, elevated CO2, photosynthesis, geranium.
Ultrastructural changes of the endosymbionts of Azolla microphylla during megaspore germination and early plantlet development
Authors: Aulfinger H. , Braun-Howland E. B. , Kannaiyan S. , Nierzwicki-Bauer S. A.
Published: December 2007

The ontological changes in cyanobacterial ultrastructure, including akinete germination and heterocyst differentiation, during the propagation of mature sporophytes from Azolla microphylla sporocarps were examined using transmission electron microscopy. Rehydrated Azolla megasporocarps contained cyanobacterial akinetes having a multilayered envelope and large amounts of cyanophycin and glycogen. Concomitant with the initial stages of sporocarp germination was the formation of vegetative cyanobacterial cells via germination of akinetes. Once fern plantlets had four visible leaves, vegetative cyanobacterial cells had begun to differentiate into heterocysts in the cavity of the oldest leaf; this timing was very similar to that observed in vegetatively reproducing sporophytes. Ultrastructural characteristics of vegetative cyanobacterial cells present at the apical meristem of plants generated either by sporocarp germination or vegetative propagation were indistinguishable. These cells remained in an undifferentiated state regardless of plant age. However, as in vegetatively propagated plants, the cyanobacterial population and ultrastructural characteristics of cells in older leaf cavities were exceedingly diverse. This is the first report that groups of pleomorphic eubacteria are contained beneath the indusium of rehydrated Azolla microphylla megasporocarps. Concomitant with the early morphological changes of germination of Azolla megasporocarps and endosymbiotic akinetes was the initiation of cell division by the eubacteria. Key words: akinetes, Azolla–Anabaena, endosymbionts, sporocarp.
Breeding systems and related floral traits in several Erysimum (Cruciferae)
Authors: Feliner Gonzalo Nieto
Published: December 2007

The breeding system of 13 populations belonging to eight species of Erysimum (Cruciferae) was studied and its relation with the life-span of the plants is discussed. To assess the breeding system of each population, greenhouse tests for apomixis, self-compatibility, and self-pollination were carried out, morphological characters like petal size and anther length were measured and pollen to ovule ratios were computed. The evidence gathered supports the selfing behavior of the three annuals, E. cheiranthoides L., E. incanum G. Kunze, and E. repandum L., and the outcrossing behavior of the perennials E. linifolium (Pers.) Gay, E. asperum (Nutt.) DC, and E. menziesii (Hook.) Wettst. Among those two groups, E. inconspicuum (S. Wats.) MacMillan and E. suffruticosum Sprengel apparently occupy an intermediate position, although the former tends more towards autogamy, whereas the latter tends towards allogamy. The importance of the breeding system data in the systematics of this genus, particularly, in studying the apparent links between the Mediterranean annuals and the temperate E. hieracifolium L. group is briefly discussed. Key words: Erysimum, breeding systems, pollen to ovule ratio, life-span.
Carbohydrate accumulation and turgor maintenance in seedling shoots and roots of two boreal conifers subjected to water stress
Authors: Koppenaal R. S. , Tschaplinski T. J. , Colombo S. J.
Published: December 2007

Water potential components and organic solutes were examined in shoots and roots of potted jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) seedlings after exposure to 7 days of water stress. The osmotic potential at the turgor loss point (ψπTLP) decreased in shoots and roots of water-stressed seedlings of both species, resulting in the maintenance of positive turgor at lower xylem water potentials (ψX) compared with nonstressed seedlings. Following water stress, ψπTLP of shoots and roots declined by 0.28 MPa and 0.14 MPa, respectively, in jack pine, and 0.19 MPa and 0.28 MPa, respectively, in white spruce. The osmotic potential at saturation (ψπ100) was significantly lower after water stress only in jack pine roots. Active osmotic adjustment during water stress was confirmed by higher concentrations of organic solutes in white spruce shoots (1.4 × increase relative to nonstressed plants) and roots (1.7 ×) and in the roots (2.2 ×) but not the shoots of jack pine. Carbohydrates, particularly fructose and glucose, were the primary organic solutes accumulating in both species. Tissue elasticity was greater in the roots than the shoots of both jack pine and white spruce regardless of treatment. Consequently, the relative water content at the turgor loss point was 22% and 18% lower in the roots than in the shoots of jack pine and white spruce, respectively. Osmotic adjustment in the roots and shoots of these two boreal conifers suggests that preconditioning planting stock by exposure to water stress may increase carbohydrate concentrations and enhance seedling drought tolerance. Key words: carbohydrate accumulation, drought tolerance, organic solutes, osmotic adjustment, Picea glauca, Pinus banksiana, water potential components.
The development of spatial pattern in shoots of Linaria vulgaris (Scrophulariaceae) growing on fallow land or in a barley crop
Authors: Nadeau Léonie B. , Dale Mark R. T. , King Jane R.
Published: December 2007

Linaria vulgaris root pieces 10 cm long with 10 cm tall shoots were planted with a barley crop and on fallow land in 1988 and 1989. Positions of new shoots of L. vulgaris were recorded once a week throughout both summers. Densities of L. vulgaris stands growing on fallow land were similar in both 1988 and 1989, ranging from 167 shoots∙m−2 in August to 247 shoots∙m−2 in October. Densities of L. vulgaris stands growing with a barley crop varied between years, ranging between 1587 and 539 shoots∙m−2 from August to October in 1988 and being relatively stable at 95 shoots∙m−2 between August and October in 1989. Stand diameter was consistently greater when on fallow land than in barley, with a maximum diameter of 1 m in 1988 and 2 m in 1989 when on fallow land, and a maximum diameter of 40 cm in 1988 and 1 m in 1989 in barley. In both years, new shoots produced in a week emerged in primary clumps 5–10 cm in diameter, and these were aggregated into secondary clumps that grew larger with time. Primary clumps on fallow land were produced in rings around initial stands, whereas when growing with barley they were scattered around and within initial L. vulgaris stands. Key words: spatial pattern, pattern of shoot growth, Linaria vulgaris, toadflax.
Immunocytochemical localization of wheat prolamins in the lumen of the rough endoplasmic reticulum
Authors: Krishnan Hari B. , White Jerry A. , Pueppke Steven G.
Published: December 2007

Antibodies raised against gliadins, the alcohol-soluble proteins of wheat (Triticum aestivum L.) seeds, were used to localize gliadins within the lumen of the endoplasmic reticulum. Endosperm cells at 20 days after anthesis contain extensive rough endoplasmic reticulum that is fragmented and dilated. The dilated endoplasmic reticulum encloses aggregates of proteinaceous material that reacts strongly with gliadin-specific antibodies. Key words: gliadins, immunocytochemistry, protein A – gold, rough endoplasmic reticulum, wheat.
Influence of a negatively charged surface (Teflon disk) on Entomophaga aulicae protoplast morphogenesis under mass fermentation conditions
Authors: Nolan Richard A.
Published: December 2007

The effects of a negatively charged surface (Teflon disk) on protoplast morphogenesis for the fungus Entomophaga aulicae under mass fermentation conditions were determined. The control consisted of a vessel lacking such a disk. In the presence of the disk the initial three and sequentially produced protoplast stages (spindle shaped, early fusion sphere, and late fusion sphere protoplasts) recycled with the early fusion sphere predominating. The production of the subsequent and walled stage (i.e., hyphal body) was suppressed. The results are in contrast with those obtained in a previous study using a neutral (Mylar) and a positively charged (polypropylene) disk in which hyphal body production was enhanced. This technique provides a new and subtle approach for altering protoplast developmental patterns which avoids the use of mutagens or added chemical metabolic inhibitors. Key words: Entomophaga aulicae, fungal protoplast morphogenesis, negatively charged surface, mass fermentation.
Association between Alternaria macrospora and Alternaria alternata, causal agents of cotton leaf blight
Authors: Bashan Yoav , Levanony Hanna , Or Reuven
Published: December 2007

The association between Alternaria macrospora and Alternaria alternata, responsible for the development of alternaria blight disease in cotton, was evaluated in artificially inoculated greenhouse plants and in naturally infested field plants. When greenhouse plants were inoculated with suboptimal doses of both pathogens (< 1.2 × 104 spores/mL) infection was greater than when separately inoculated by each pathogen at optimal dosage. In field-grown, naturally infected plants (Gossypium barbadense), both pathogens were found together in more than 40% of the plants. A second field-grown cotton species (Gossypium hirsutum) exhibited infection mainly by either A. alternata or both pathogens together. When both cotton species were naturally infected by both pathogens together, the number of A. alternata spores (either airborne or on the leaf surface) was greater than that of A. macrospora. We propose that A. macrospora together with A. alternata create a disease composite responsible for alternaria blight symptoms in cotton. Key words: Alternaria, cotton diseases, Gossypium barbadense, Gossypium hirsutum.
Inheritance and characterization of a dark-germinating, light-inhibited mutant in the fern Ceratopteris richardii
Authors: Scott Rodney J. , Hickok Leslie G.
Published: December 2007

Selection for a dark-germinating mutant was made with X-irradiated spores of Ceratopteris richardii. A single mutant line (HαDG1) was recovered and analyzed for its germination responses under different light–dark treatments and for transmission of the trait through a complete sexual cycle. HαDG1 was characterized by two phenotypes, dark germination and light inhibition of germination. These responses were exactly opposite from wild-type responses. The level of dark germination for a particular spore batch was stable through time, whereas light inhibition was unstable with time. Genetic analysis indicated that both phenotypes are associated with a single nuclear gene mutation that has been designated dkg1. Key words: fern, photomorphogenesis, mutant selection, germination, spore.