Variation in Nickel Content in the Nickel-Hyperaccumulating Shrub Psychotria douarrei (Rubiaceae) from New Caledonia1

Plants that hyperaccumulate Ni contain > 1000 ppm (dry wt.) in their tissues. Variation of Ni content within hyperaccumulating plant species is poorly explored. Using the Ni-hyperaccumulating shrub Psychotria douarrei, we documented variation of leaf Ni levels within individual shrubs, and variation with respect to plant size and leaf age. Plant size did not correlate significantly with leaf Ni content, and leaf Ni content did not correlate significantly with soil Ni content. Older leaves contained twice as much Ni as younger leaves. Older leaves also contained greater concentrations of Ca, Fe, and Cr but less K, P, and Cu. Five elements (Zn, Pb, Co, Mn, Mg) showed no significant variation due to leaf age. We also examined the effect of leaf age on epiphyll cover, finding increased epiphyll cover on the upper surface of older leaves. The dominant leafy liverwort epiphyll had a relatively high Ni content (400 ppm), suggesting that epiphylls of Ni hyperaccumulators obtain some Ni from host leaves. Individual shrubs differed in mean leaf Ni content almost two-fold (14,900-27,700 ppm). Variation among branches within individuals also ranged widely; however, this intraplant variability was not strongly correlated with the mean leaf Ni content of an individual shrub. We concluded that Ni contents in leaves of P. douarrei vary considerably due to leaf age, among individual shrubs, and among branches within a shrub.     

Morphology, Anatomy and Ontogeny of Female Cones in Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)

The developmental morphology and anatomy of the female conesof Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)are described and illustrated, based on observations, histology,scanning electron microscopy (SEM) and nuclear magnetic resonance(NMR) imaging. Ovulate development is typically podocarpaceous.Ovules are unitegmic, and horizontal or inclined upwards throughoutontogeny; the pollination drop is inverted because of the declinatemicropyle. Ontogeny of the epimatium-ovule complex is acropetal,the epimatium developing first. A terminal, distal sterile bractcreates a pollen-scavenging area. During development, the wholecone re-orientates through some 270°, and the seed realignsapprox. 60° with respect to the receptacle axis. The ‘receptacle’or podocarpium supporting the seed is formed by gradual fusionof initially free bracts. The structures adnate to these bractsrepresent homologues of ovuliferous scales; they bear vestigialepimatia which may develop into supernumerary ovules or non-functionalepimatia. Thus, female cones ofA. pancheri are vestigially multi-ovulate.NMR imaging effectively and non-invasively revealed the three-dimensionalarrangement of vascular bundles and resin canals in the cones.Copyright 2001 Annals of Botany Company Acmopyle pancheri(Brongn. & Gris) Pilg., anatomy, developmental morphology, gymnosperms, histology, nuclear magnetic resonance (NMR) imaging, ontogeny, ovules, Podocarpaceae, scanning electron microscopy (SEM), seed cones     

Nature of nickel complexes in Psychotria douarrei and other nickel-accumulating plants

The nature of nickel complexes in various Ni accumulating plant species, mainly from New Caledonia, was investigated by techniques including gel chromatography, ion-exchange chromatography, high performance liquid chromatography, and a combination of gas-liquid chromatography and mass spectrometry. Psychotria douarrei contained Ni complexed mainly (63%) as a negatively-charged malate complex balanced by a cationic aquo complex. Phyllanthus serpentinus had anionic Ni bound as 42% citrate and 4O% malate. All other species studied, contained Ni as an anionic citrate complex.     

Various types of tryptamine-iridoid alkaloids from Palicourea acuminata (=Psychotria acuminata,Rubiaceae)

The novel tryptamine-iridoid alkaloid lagamboside was isolated from the methanolic leaf extracts of Palicourea acuminata (Benth.) Borhidi (=Psychotria acuminata Benth.) collected in Costa Rica. Its structure was determined by extensive NMR experiments and is characterized by an unusual N-glycosylation and an iridoid moiety closely related to the less common vallesiachotamine. The co-occurrence with the rare bahienoside, containing two iridoid moieties, is of chemotaxonomic interest.     

Isolation and identification of a citrato-complex of nickel from nickel-accumulating plants

An organometallic complex of nickel has been isolated from nickel-accumulating plants of New Caledonia and has been identified by a combination of infrared spectroscopy, high-voltage paper electrophoresis, gas-liquid chromatography and mass spectrometry. Most of the nickel in Sebertia acuminata, Homalium francii, Homalium guillainii, Homalium kanaliense, Hybanthus austrocaledonicus and Hybanthus caledonicus is found as a negatively-charged citratonickelate (II) complex with Ni(H₂O)₆²⁺ as the major cationic constituent.     

Interaction of nickel and manganese in accumulation and localization in leaves of the Ni hyperaccumulators Alyssum murale and Alyssum corsicum

The genus Alyssum contains >50 Ni hyperaccumulator species; many can achieve >2.5% Ni in dry leaf. In soils with normal Mn levels, Alyssum trichome bases were previously observed to accumulate Ni and Mn to high levels. Here we report concentration and localization patterns in A. murale and A. corsicum grown in soils with nonphytotoxic factorial additions of Ni and Mn salts. Four leaf type subsets based on size and age accumulated Ni and Mn similarly. The greatest Mn accumulation (10 times control) was observed in A. corsicum with 40 mmol Mn kg^?1 and 40 mmol Ni kg^?1 added to potting soil. Whole leaf Ni concentrations decreased as Mn increased. Synchrotron X-ray fluorescence mapping of whole fresh leaves showed localized in distinct high-concentration Mn spots associated with trichomes, Ni and Mn distributions were strongly spatially correlated. Standard X-ray fluorescence point analysis/mapping of cryofractured and freeze-dried samples found that Ni and Mn were co-located and strongly concentrated only in trichome bases and in cells adjacent to trichomes. Nickel concentration was also strongly spatially correlated with sulfur. Results indicate that maximum Ni phytoextraction by Alyssum may be reduced in soils with higher phytoavailable Mn, and suggest that Ni hyperaccumulation in Alyssum species may have developed from a Mn handling system.     

A morphological and chemical study of Populus acuminata Rydberg

Evidence from morphology, flavonoid chemistry, and field observations suggests thatPopulus acuminata is of hybrid origin. The putative parents areP. angustifolia, the narrow leaf cottonwood, and deltoid leaved plants that are assigned toP. sargentii (P. deltoides var.occidentalis), P. fremontii, orP. wislizenii (P. fremontii var.wislizenii). Populus angustifolia exhibits a series of flavonol glycosides (kaempferol, quercetin, and myricetin) in its leaves. By contrast, the major leaf flavonoids of the broad leaved plants are flavone glycosides (apigenin and luteolin).Populus acuminata is intermediate between the suspected parents in morphological features. Additionally, the leaves of mostP. acuminata plants contain the exact summation of the flavonoid compounds characteristic of the putative parents. A diploid chromosome number of 2n = 38 was obtained for six plants, which confirms the one previous report for the species. Meiosis was regular in all cases. Correlated data indicate that the majority of plants ofP. acuminata represent F₁ hybrids and that complex hybridization is not common. Evidence from morphological and chemical studies is presented to show that in certain instances backcrossing to both parents has occurred. Results gathered in this study show thatP. ×andrewsii is undoubtedly “typical”P. acuminata, but the type specimen is from a sucker shoot, and thus has been interpreted as a backcross toP. sargentii. Populus acuminata var.rehderi is not considered worthy of taxonomic recognition.     

中国瓜馥木属(番荔枝科)一新记录种

报道了中国番荔枝科瓜馥木属(Annonaceae:Fissistigma)一新记录种——瘤果瓜馥木[F.thorelii(Pierre ex FinetGagnep.)Merr.]。该种在中国产于云南省红河县,凭证标本保存在西双版纳热带植物园标本馆(HITBC)。该种的主要特征是幼枝、花、果均被褐色粗短硬毛,且果实表面布满瘤状突起。     

Trace elements accumulation and temporal trends in leaves of urban deciduous trees (Aesculus hippocastanum and Tilia spp.)

Leaves of common deciduous trees: Aesculus hippocastanum and Tilia spp. from three parks within the urban area of Belgrade (Serbia) were studied as biomonitors of trace elements (Cr, Fe, Ni, Cu, Zn, and Pb) atmospheric pollution. The seasonal trace elements accumulation (September/May) in the leaves, and their temporal trends, were assayed in a multy-year period (2002–2006). Significant seasonal accumulation was evident in samples of A. hippocastanum for: Cr, Fe, Ni, Zn, and Pb, as well as in Tilia spp. leaves, except for Zn. For Cu, no regular seasonal accumulation was observed in leaves of the studied species. Decreasing temporal trend in leaf tissue concentrations were evident for Pb in A. hippocastanum (16.0 μg g^?1 in September of 2002 to 4.6 μg g^?1 in September of 2006) which is in accordance with the bulk atmospheric deposition measurements. The leaf Cu concentrations were the highest at one of the studied sites, also marked previously with extremely high atmospheric Cu loadings by some other monitoring (bulk deposition, particulate matter, moss) surveys. Decreasing Cu concentrations temporal trend at that site in the leaves of A. hippocastanum was evident through the studied years and also confirmed with the bulk deposition measurements. The Cr, Fe, Ni, and Zn leaf tissue concentrations remained at about the same level in the studied species throughout the experiment and no agreement was observed with the bulk deposition data. Comparing the studied biomonitors, the leaves of A. hippocastanum showed significantly higher elements accumulation and more consistency than Tilia spp., so it may be considered as more suitable species for assessment of Pb and Cu atmospheric pollution.     

Are the mitochondrial cox1 and cob genes suitable markers for species of Dinophysis Ehrenberg?

The identification of Dinophysis species with similar morphology but different toxic (Diarrhetic Shellfish Poisoning, DSP) potential is a crucial task in harmful algae monitoring programmes. The taxonomic assignment of Dinophysis species using molecular markers is a difficult task due to extremely low interspecific variability within their nuclear ribosomal genes and intergenic regions. Mitochondrial cox1 gene has been proposed as a better specific marker for Dinophysis species based on its higher resolution for two morphologically related species (Dinophysis acuminata and Dinophysis ovum) of the “Dinophysis acuminata complex”. In this study, the potential of two mitochondrial genes (mt cox1 and cob) to discriminate among six Dinophysis species (field isolates and cultures) associated with DSP events was explored. Neither mt cox1 nor cob genes provided enough resolution for all species of Dinophysis. The cob gene showed very poor resolution and grouped all Dinophysis spp. in a common clade. In contrast, the cox1 phylogeny distinguished 5 clades in the Dinophysiales – the “acuminata complex”, the “caudata group”, “acuta + norvegica” and Phalacromaspp. However, within the “D. acuminata complex” mtcox1 is so far the unique marker that differentiates D. acuminata from other species: isolates of D. ovum and Dinophysis sacculus had almost identical sequences (only four mismatches), but they were well separated from D. acuminata. D. acuminata and Dinophysis skagii (considered a life cycle stage of the former) showed identical cox1 sequences. Probes towards this gene can be useful in Mediterranean and Western Iberia sites where the co-occurrence of close morphotypes of D. acuminata and D. sacculus pose a problem for monitoring analyses. This is the first report on cultures of D. sacculus and its phylogenetic relation with other species of the D. acuminata complex.     

Correlations between salinity and growth of the seagrass Amphibolis antarctica (labill.) Sonder & Aschers., In Shark Bay,Western Australia,using a new method for measuring production rate

A method of estimating above-ground productivity in situ of the seagrass Amphibolis antarctica (Labill.) Sonder & Aschers. has been devised, using tags to determine rates of leaf turnover. This has proved an effective tool in establishing the behavior of the species in relation to the gradient of increasing salinity which is present in Shark Bay. No seagrass was found beyond 64%_o, but measurement of production and biomass within dense patches of seagrass at different salinities revealed that these were at a maximum at a salinity of 42%_o, decreasing as the salinity increased and also at lower oceanic concentrations. Production rates ranged from 2 to 17 g dry weight m^?2 day^?1 with biomass from 600 to 2000 g m^?2, thus Amphibolis antarctica is one of the more productive Australian seagrass species, even in the hypersaline conditions of the Bay. Despite the obvious correlation between above-ground production and salinity, it is pointed out that the results are not taken to imply causality.     

Psednotrichia perennis (Asteraceae,Senecioneae): A new species from the Huila plateau,Angola

The genus Psednotrichia (Asteraceae–Senecioneae) is endemic to Angola and currently consists of two annual species, P. xyridopsis (O. Hoffm.) Anderb. & P. O. Karis, and P. newtonii (O. Hoffm.) Anderb. & P. O. Karis. A perennial member of the genus was collected on a recent field trip to Angola, and is here described as P. perennis N. G. Bergh & B. Nord., sp. nov. A key to the three species is provided.     

Production of dinophysistoxin-1 and pectenotoxin-2 by a culture of Dinophysis acuminata (Dinophyceae)

The production of diarrhetic shellfish poisoning toxins (okadaic acid analogues and other lipophilic toxins) by a culture of Dinophysis acuminata, fed with the autotrophic ciliate Myrionecta rubra, was confirmed by LC–MS analysis, and the toxin profile compared with that in the field assemblage of the same species. The growth response of D. acuminata to the density of the food organism was also examined in laboratory experiments. In semi-continuous culture experiments, the growth rates of D. acuminata increased with increasing density of M. rubra and a maximum growth rate of 0.67 per day was calculated. In batch culture experiments; the cellular content of PTX2 and DTX1 were 14.7–14.8 and 2.5–4.8 pg cell^?1, respectively. Okadaic acid, dinophysistoxin-3, pectenotoxin-1, pectenotoxin-6, yessotoxin (YTX) and 45-OHYTX were not detected. PTX2 was detected (cellular toxin content: 22 pg cell^?1), but DTX1 was not detected, in an extract of D. acuminata collected from natural seawater at the same location where the cultured D. acuminata specimens were isolated. These results strongly suggest that D. acuminata produces these toxins during cell growth and that environmental factors influence variations in the toxin composition and specific cellular toxicity.     

Multiscale and age-dependent leaf nickel in the Ni-hyperaccumulator <Emphasis Type="Italic">Leptoplax emarginata</Emphasis>

Nickel-hyperaccumulator plants are of interest due to their potential use in agromining. We aimed to characterize leaf traits and Ni concentration variabilities occurring between individual plants, leaves of differing age or between various leaf tissues, in a single Greek population of the Ni-hyperaccumulator Leptoplax emarginata (Boiss.) O.E. Schulz. We linked these results to ecophysiological characteristics and other element concentrations at leaf and leaf tissue scales. We measured leaf gas exchanges, stomatal density, and we carried out rapid freezing and freeze-drying processes on leaf sections before microanalysis with scanning electron microscopy and energy-dispersive spectrometry. Leaf or leaf-tissue Ni concentrations were influenced by a combination of individual plant and leaf age factors. The greatest Ni concentrations were found in the highly transpiring young and thin leaves with the greatest stomatal densities. Indeed, Ni was statistically seven times more concentrated in both epidermis layers than in their bulk neighbour leaf counterparts, whatever the leaf age. In both epidermis layers, increases in the Ni–S and Mg–S correlations from the oldest leaves to the youngest ones were observed. The Mg:Ni, Ca:Ni and P:Ni mass ratios decreased from the oldest leaves to the mature leaves. We would recommend time-series characterization of leaf traits belonging to at least three plant replicates in order to take into account the allogamous character of many Ni-hyperaccumulator plants. Long-distance Ni transport via the xylem is predominant in the Ni-hyperaccumulator L. emarginata whereas a complementary redistribution via the phloem should also occur. The perspectives of this study are the validation and refinement of this process over shorter periods using relevant tracers.     

Host range of Neozygites floridana isolates (Zygomycetes: Entomophthorales) to spider mites

Neozygites floridana (Weiser & Muma) (Zygomycetes: Entomophthorales) has been reported infecting naturally at least 18 species of tetranychids worldwide. However, the host range of N. floridana is unknown. Epizootics caused by this pathogen to tetranychid populations indicate that N. floridana has the potential to be used as a biological control agent. However, the virulence and specificity of species and strains of Neozygites need to be assessed in the laboratory to reveal its potential as a biological control agent. N. floridana isolates are currently been investigated in Brazil as biological control agents against the tomato red mite, Tetranychus evansi Baker & Pritchard, and the two-spotted spider mite, Tetranychus urticae Koch. The pathogenicity of five strains of N. floridana obtained from T. urticae, T. evansi and T. ludeni Zacher was assessed against populations of Mononychellus tanajoa (Bondar), Schizotetranychus sacharum Flechtmann & Baker, Tetranychus abacae Baker & Pritchard and Tetranychus armipenis Flechtmann & Baker, in addition to the species from which the fungus was obtained. Mummified mites were placed on leaf discs of the host plant of each tetranychid to promote fungal sporulation, and after 24 h the mites were transferred to the leaf discs. Contamination, infection and mummification were evaluated daily for seven days after confinement. Each isolate was pathogenic to three or four out of the six spider mite species tested. However, except for isolate ESALQ1421, all isolates caused higher levels of infection and significant mummification only to the tetranychid species from which they were collected. None of the isolates was pathogenic to S. sacharum and only one isolate infected T. abacae. Alternative hosts may be important for N. floridana survival in tropical regions where resting spores are rarely found.