ELECTROPHORETIC CONFIRMATION OF INTERSPECIFIC HYBRIDIZATION IN AESCULUS (HIPPOCASTANACEAE) AND THE GENETIC STRUCTURE OF A BROAD HYBRID ZONE

Within a broad (>200 km wide) hybrid zone involving three parapatric species of Aesculus, we observed coincident clines in allele frequency for 6 of 14 electrophoretic loci. The cooccurrence of alleles characteristic of A. pavia, A. sylvatica, and A. flava was used to estimate genetic admixtures in 48 populations involving various hybrids between these taxa in the southeastern United States. High levels of allelic polymorphism (up to 40% greater than the parental taxa) were observed in hybrid populations and also in some populations bordering the hybrid zone. A detailed analysis of a portion of the hybrid zone involving A. pavia and A. sylvatica revealed a highly asymmetrical pattern of gene flow, predominantly from Coastal Plain populations of A. pavia into Piedmont populations of A. sylvatica. Computer simulations were used to generate expected genotypic arrays for parental, F₁; and backcross individuals, which were compared with natural populations using a character index scoring system. In these comparisons, hybrid individuals could be distinguished from either parent, but F₁ and backcross progeny could not be distinguished from each other. Most hybrid populations were found to include hybrids and one of the parental taxa, but never both parents. Three populations appeared to be predominantly hybrids with no identifiable parental individuals. Hybrids occurred commonly at least 150 km beyond the range of A. pavia, but usually not more than 25 km beyond the range of A. sylvatica. Introgression, suggested by genetically hybrid individuals and significant gene admixtures of two or more species in populations lacking morphological evidence of hybridization, may extend the hybrid zone further in both directions. The absence of one or both parental species from hybrid populations implies a selective disadvantage to parentals in the hybrid zone and/or that hybridization has occurred through long-distance gene flow via pollen, primarily from A. pavia into A. sylvatica. Long-distance pollen movement in plants may generate hybrid zones of qualitatively different structure than those observed in animals, where gene flow involves dispersal of individuals.     

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.     

三种山茶属金花茶组植物花朵类黄酮成分研究

该研究以山茶属金花茶组的金花茶、凹脉金花茶和崇左金花茶为材料,利用超高效液相色谱-四极杆-飞行时间质谱联用技术定性定量分析其花朵中类黄酮成分与含量。结果表明:三种植物中检测到15种类黄酮,其中天竺葵素-3-O-葡萄糖苷、木犀草素、木犀草素-7-O-芸香糖苷、槲皮素-3,7-O-二葡萄糖苷、芸香柚皮苷、圣草素和染料木苷为金花茶组首次发现;槲皮素-3-O-葡萄糖苷、槲皮素-7-O-葡萄糖苷、槲皮素-3-O-芸香糖苷和山萘酚-3-O-葡萄糖苷为凹脉金花茶和崇左金花茶中首次发现。儿茶素、表儿茶素、槲皮素-3-O-葡萄糖苷、槲皮素-7-O-葡萄糖苷、槲皮素-3-O-芸香糖苷和山萘酚-3-O-葡萄糖苷为三个物种主体成分;天竺葵素-3-O-葡萄糖苷为金花茶特有,槲皮素-3,7-O-二葡萄糖苷为崇左金花茶特有;木犀草素-7-O-芸香糖苷主要存在于金花茶和崇左金花茶;木犀草素主要存在于凹脉金花茶和崇左金花茶。类黄酮类型主要为儿茶素类、槲皮素类、木犀草素类和山萘酚类;崇左金花茶中槲皮素类、木犀草素类及类黄酮总量远高于金花茶和凹脉金花茶,凹脉金花茶和崇左金花茶儿茶素类高于金花茶,金花茶和崇左金花茶山萘酚类高于凹脉金花茶。     

Anticonvulsant, antidepressant-like activity of Abelmoschus manihot ethanol extract and its potential active components in vivo

Depression is the most common psychiatric comorbidity in patients with epilepsy. Searching for antiepileptic (anticonvulsant) and antidepressant-like medicines from natural products is very important for the treatment of this disease. The flower of Abelmoschus manihot (Linn.) Medicus has been reported to have neuroprotective effect against cerebral ischemia injury. In order to further explore the activity of Abelmoschus manihot on the central nervous system, the anticonvulsant and antidepressant-like effects of Abelmoschus manihot ethanol extract (AMEE) as well as its potential active components in vivo was investigated in the present study. It was found that AMEE could protect mice against PTZ-induced clonic convulsions and mortality. AMEE could also decrease immobility time in the FST in mice. Furthermore, the potential active components of AMEE in rat brain were identified by ultra performance liquid chromatography-mass spectrometer (UPLC-MS). Five parent components including isoquercitrin, hyperoside, hibifolin, quercetin-3′-O-glucoside, quercetin and three metabolites were detected in rat brain after administration of AMEE. In conclusion, eight flavonoids were identified in rat brain after administration of AMEE; meanwhile, these flavonoids might represent the potential bioactive components of AMEE and contribute to its anticonvulsant and antidepressant-like activity in vivo.     

Preformation and distribution of staminate and pistillate flowers in growth units of Nothofagus alpina and N. obliqua (Nothofagaceae)

Background and Aims

The distribution and differentiation times of flowers in monoecious wind-pollinated plants are fundamental for the understanding of their mating patterns and evolution. Two closely related South American Nothofagus species were compared with regard to the differentiation times and positions of staminate and pistillate flowers along their parent growth units (GUs) by quantitative means.

Methods

Two samples of GUs that had extended in the 2004–2005 growing season were taken in 2005 and 2006 from trees in the Lanín National Park, Patagonia, Argentina. For the first sample, axillary buds of the parent GUs were dissected and the leaf, bud and flower primordia of these buds were identified. The second sample included all branches derived from the parent GUs in the 2005–2006 growing season.

Key Results

Both species developed flowering GUs with staminate and/or pistillate flowers; GUs with both flower types were the most common. The position of staminate flowers along GUs was similar between species and close to the proximal end of the GUs. Pistillate flowers were developed more distally along the GUs in N. alpina than in N. obliqua. In N. alpina, the nodes bearing staminate and pistillate flowers were separated by one to several nodes with axillary buds, something not observed in N. obliqua. Markovian models supported this between-species difference. Flowering GUs, including all of their leaves and flowers were entirely preformed in the winter buds.

Conclusions

Staminate and pistillate flowers of N. alpina and N. obliqua are differentiated at precise locations on GUs in the growing season preceding that of their antheses. The differences between N. alpina and N. obliqua (and other South American Nothofagus species) regarding flower distribution might relate to the time of anthesis of each flower type and, in turn, to the probabilities of self-pollination at the GU level.Key words: Branch, bud, growth unit, Markovian models, Nothofagus alpina, N. obliqua, Patagonian forests, pistillate flower, preformation, staminate flower     

Variation and taxonomy of Aesculus pavia L. (Hippocastanaceae) in Texas

The status of Aesculus pavia var. flavescens, a set of yellow-flowered populations endemic to the Edwards Plateau of central Texas, was evaluated on the basis of comparative morphology, geography, flowering phenology, and pollination ecology. Plants of typical A. pavia have red, tubular flowers with exserted stamens and are effectively pollinated by ruby-throated hummingbirds. Plants of var. flavescens have yellow, campanulate flowers with included stamens that can be pollinated effectively by large bees. These ethological reproductive isolating mechanisms are further augmented by a difference in flowering time between the two sets of populations and by geographical restriction of the yellow-flowered plants to localities on the Edwards Plateau. The yellow and red-flowered plants constitute two morphologically distinct groups, despite evidence of limited introgression in counties along the Balcones Escarpment. A yellow-flowered plant discovered in coastal east Texas may indicate the mechanism by which var. flavescens originated, but this plant is much more closely comparable to typical red-flowered var. pavia than to the yellow-flowered plants on the Edwards Plateau. An evolutionary history of section Pavia of Aesculus is presented, and it is concluded that the yellow-flowered plants of central Texas are best regarded as a taxonomic variety.     

Genetic variation of horse chestnut and red horse chestnut and trees susceptibility to Erysiphe flexuosa and Cameraria ohridella

Trees of Aesculus sp. are often present in European landscapes. Common horse chestnut and red horse chestnut are seriously damaged by the fungus Erysiphe flexuosa as well as the pest Cameraria ohridella. Both pathogen and pest have spread throughout Europe. A genetic background of trees resistance still remains unknown. The present study was undertaken to estimate genetic variation of A. hippocastanum and A.×carnea grown in urban greens and their susceptibility to powdery mildew and horse chestnut leafminer. According to obtained results both species were infected by E. flexuosa in a similar degree but there were significant differences in susceptibility of particular trees (ANOVA). C. ohridella damaged only A. hippocastanum. The correlation between age of trees and degree of infestation by pathogen and pest was not observed. The significant genetic variability between two Aesculus species was revealed by the analysis of molecular variance (AMOVA) where both the intra- and the inter-species variation were found to be significant. It was shown that 73.0% of the genetic variance was contributed by the differentiation between A. hippocastanum and A.×carnea, whereas 27.0% was partitioned within species. The medium level of genetic diversity of Aesculus spp. was determined using SRAP and RAPD analyses. The mean value of genetic similarity was equal to 0.55 for common horse chestnut and 0.98 for red horse chestnut. Among 40 polymorphic SRAP and RAPD markers 17 were associated with degree of leaf damage caused by C. ohridella.     

Floral structure and development in the monoecious palm Gaussia attenuata (Arecaceae; Arecoideae)

Background and Aims

Sexual dimorphism, at both the flower and plant level, is widespread in the palm family (Arecaceae), in contrast to the situation in angiosperms as a whole. The tribe Chamaedoreeae is of special interest for studies of the evolution of sexual expression since dioecy appears to have evolved independently twice in this group from a monoecious ancestor. In order to understand the underlying evolutionary pathways, it is important to obtain detailed information on flower structure and development in each of the main clades.

Methods

Dissection and light and scanning electron microscopy were performed on developing flowers of Gaussia attenuata, a neotropical species belonging to one of the three monoecious genera of the tribe.

Key Results

Like species of the other monoecious genera of the Chamaedoreeae (namely Hyophorbe and Synechanthus), G. attenuata produces a bisexual flower cluster known as an acervulus, consisting of a row of male flowers with a basal female flower. Whereas the sterile androecium of female flowers terminated its development at an early stage of floral ontogeny, the pistillode of male flowers was large in size but with no recognizable ovule, developing for a longer period of time. Conspicuous nectary differentiation in the pistillode suggested a possible role in pollinator attraction.

Conclusions

Gaussia attenuata displays a number of floral characters that are likely to be ancestral to the tribe, notably the acervulus flower cluster, which is conserved in the other monoecious genera and also (albeit in a unisexual male form) in the dioecious genera (Wendlandiella and a few species of Chamaedorea). Comparison with earlier data from other genera suggests that large nectariferous pistillodes and early arrest in staminode development might also be regarded as ancestral characters in this tribe.     

Phenolics in the Strawberry Root

Roots of four strawberry cultivars contained phenolics previouslyisolated from the fruits and leaves; others were found whichapparently have not been reported. Catechin, gallic acid, andthree biflavans were the most prominent as spots on paper chromatograms.Kaempherol-7-glucoside, quercetin-7-glucoside, an unidentifiedflavanone glycoside, ellagic acid, an ellagic acid derivative,a galloyl ester, and two other hydrolysable tannins were detected.A leucoanthocyanin, cyanidin-3-monoglucoside, chlorogenie acid,a scopoletin glycoside, a derivative of arbutin, DOPA (3,4-dihydroxyphenylalanine),and three unidentified polyphenols comprised the other phenolicscommon to the four cultivars. A xanthone was found in only oneof four cultivars, Howard 17.     

Inflorescence morphology and flower development in Pinguicula alpina and P. vulgaris (Lentibulariaceae: Lamiales): monosymmetric flowers are always lateral and occurrence of early sympetaly

Earlier interpretations of shoot morphology and flower position in Pinguicula are controversial, and data on flower development in Lentibulariaceae are scarce. We present scanning electron microscopy about the vegetative shoot, inflorescence and flower development in Pinguicula alpina and P. vulgaris. Analysis of original data and the available literature leads to the conclusion that the general pattern of shoot branching and inflorescence structure is uniform in all the Pinguicula species studied so far. The inflorescence is a sessile terminal umbel that is sometimes reduced to a solitary pseudoterminal flower. Flower-subtending bracts are either cryptic or present as tiny scales. A next order lateral shoot develops in the axil of the uppermost leaf, below the umbel. It is usually though not always homodromous, i.e., the direction of the phyllotaxy spiral is the same as in the main shoot. Among Pinguicula species that overwinter as a hibernaculum, the initiation of floral organs takes place in the same year as flowering in P. vulgaris, and 1?year earlier in P. alpina. Early congenital petal fusion (??early?? sympetaly) is documented in Pinguicula, though most other members of Lamiales exhibit ??late?? sympetaly. Sporadic occurrence of rudiments of two posterior stamens in Pinguicula is confirmed. A speculation is made that, in angiosperms, monosymmetric flowers cannot be terminal on shoots bearing more than two (or three) phyllomes.     

A new species of Angelopteromyia Korneyev, 2001 (Diptera,Platystomatidae) from Iran,with the key to the species

Angelopteromyia korneyevi Mohamadzade Namin, sp. n. from Iran is described and figured. The new species is similar to other species of Angelopteromyia in having abdominal spiracles 5 of females not approximated medially, as well as clypeus extended postero-ventrally, antenna shorter than face, and R₁ and R₄₊₅ setulose on dorsal side. It differs from other species of Angelopteromyia by having mostly brown wing with 3 hyaline crossbands and a few hyaline spots, and dark brownish basal and costal cells without hyaline spots.     

The present status and potential distribution of relict populations of Aesculus hippocastanum L. in Greece and the diverse infestation by Cameraria ohridella Deschka & Dimić.

Aesculus hippocastanum is a well-known species, which is popular because of its ornamental value. However, data on the demographic structure and potential distribution of A. hippocastanum are limited. The invasion of Cameraria ohridella into Europe has harmed those trees growing in artificial sites, but the presence of this insect in natural stands has been little studied. Here we aimed to investigate the demographic structure infestation level of natural populations of horse-chestnut. Additionally, Maxent modelling was used to predict the potential range of A. hippocastanum, based on the localities available in the literature. Field data analysis indicated that natural populations of A. hippocastanum are mostly found nearby mountain streams. The populations showed a diverse height structure and large numbers of seedlings, which indicate high population dynamics. The level of infestation by C. ohridella varied greatly and correlated with altitude. Secondary infestation might explain this infestation variability in some natural populations. Other hypotheses, such as environmental resistance factors or different genetic variability, are also discussed. By spatial distribution modelling, we found that the precipitation of the coldest and warmest quarters, as well as altitude, are important factors influencing the potential distribution of A. hippocastanum.     

Wood preference of spalting fungi in urban hardwood species

Five fungal species representing the three major spalting categories were inoculated onto wood of five different urban tree species with low to moderate economic value. Sugar maple (Acer saccharum) was also inoculated to serve as a control. Test samples were evaluated both internally and externally for spalting. The tested fungi had significant preferences for different wood species, and the preferences appeared to be related to sucrose availability. Specifically, zone line producing fungi preferred American elm (Ulmus americana), while Arthrographis cuboidea (pink stain) preferred tree-of-heaven (Ailanthus altissima). Wood species preference was also significant by decay class, with decay fungi preferring American elm, silver maple (Acer saccharinium), and horse chestnut (Aesculus hippocastanum). Staining fungi showed a preference for tree-of-heaven, while both decay classes readily colonized sugar maple and Norway maple (Acer platanoides).     

Phytochemistry of proanthocyanidins

Procyanidin A from Aesculus hippocastanum differs from the B type procyanidin in that it is difficultly soluble in water, gives a higher yield of cyanidin when heated in butanolic HCl and the production of cyanidin continues beyond the 2 hr period sufficient for maximum production in the case of B type procyanidin. Anthocyanidin production and tannic acid equivalent (TAE) of extracts of species in which A and D type procyanidins have been reported to occur have been studied. Evidence of their presence was also found in Ribes laurifolium. Preparations of prodelphinidin from leaves of red currant and sainfoin had approximately twice the anthocyanidin production and the astringency of procyanidin B. Sources especially rich in prodelphinidin were a number of Ribes spp., Salix cinerea and Platanus acerifolia, from all of which the tannin was easily extracted. Some other species such as Pilea cadieri, although rich in prodelphinidin, are not suitable as sources because of the inextractability of the tannin.     

Do specialized flowers promote reproductive isolation? Realized pollination accuracy of three sympatric Pedicularis species

Background and Aims

Interest in pollinator-mediated evolutionary divergence of flower phenotype and speciation in plants has been at the core of plant evolutionary studies since Darwin. Specialized pollination is predicted to lead to reproductive isolation and promote speciation among sympatric species by promoting partitioning of (1) the species of pollinators used, (2) when pollinators are used, or (3) the sites of pollen placement. Here this last mechanism is investigated by observing the pollination accuracy of sympatric Pedicularis species (Orobanchacae).

Methods

Pollinator behaviour was observed on three species of Pedicularis (P. densispica, P. tricolor and P. dichotoma) in the Hengduan Mountains, south-west China. Using fluorescent powder and dyed pollen, the accuracy was assessed of stigma contact with, and pollen deposition on, pollinating bumble-bees, respectively.

Key Results

All three species of Pedicularis were pollinated by bumble-bees. It was found that the adaptive accuracy of female function was much higher than that of male function in all three flower species. Although peak pollen deposition corresponded to the optimal location on the pollinator (i.e. the site of stigma contact) for each species, substantial amounts of pollen were scattered over much of the bees'' bodies.

Conclusions

The Pedicularis species studied in the eastern Himalayan region did not conform with Grant''s ‘Pedicularis Model’ of mechanical reproductive isolation. The specialized flowers of this diverse group of plants seem unlikely to have increased the potential for reproductive isolation or influenced rates of speciation. It is suggested instead that the extreme species richness of the Pedicularis clade was generated in other ways and that specialized flowers and substantial pollination accuracy evolved as a response to selection generated by the diversity of co-occurring congeners.     

The Diversity of Flower Flies (Diptera: Syrphidae) in Colombia and Their Neotropical Distribution

In Colombia, like most Neotropical countries, faunistic studies on flower flies have been occasional and most of them have been primarily focused on taxonomy. Colombia is the second-most species-rich country in flower fly diversity in the Neotropics after Brazil, and has one of the highest numbers of species per unit area (2.49 per 10,000?km²), based on a review of literature and national collections. Including new data presented here, a total of 47 genera and 300 species are recorded in Colombia. The genera Scaeva Fabricius and Lycastrirhyncha Bigot, as well as 101 species are recorded here for the first time. The altitudinal range and the distribution of the flower fly genera in Colombia are presented. A preliminary comparison of the fauna of Colombia with that of other Neotropical countries is given. A historical perspective is also provided in order to illustrate how Colombian Syrphidae knowledge has progressed over the last 168?years. Information presented here will be useful for ongoing and future biodiversity research as well as conservation projects on Syrphidae in the Neotropical region.     

Phenolic constituents of leaves from Persea caerulea Ruiz & Pav; Mez (Lauraceae)

The chemical investigation of the ethanolic extract from the leaves of Persea caerulea led to the isolation of flavonoids, coumarins and three steroidal type compounds. Based on ESI-MS, UV, IR, GC-MS and ¹H and ¹³C NMR data analysis, the structures of ten isolated compounds were identified as: quercetin (1), kaempferide-3-O-α-l-rhamnopyranoside (2), kaempferol-3-O-α-l-arabinofuranoside (3), quercetin-3-O-α-l-rhamnopyranoside (4), quercetin-3-O-β-glucoside (5), scopoletin (6), isofraxidin (7) campesterol (8), stigmasterol (9) and β-sitosterol (10). In the current research, the isolated compounds 1–9 are reported for the first time in the species Persea caerulea.     

Pollination biology of Eulophia alta (Orchidaceae) in Amazonia: effects of pollinator composition on reproductive success in different populations

Background and Aims

Spatial variation in pollinator composition and abundance is a well-recognized phenomenon. However, a weakness of many studies claiming specificity of plant–pollinator interactions is that they are often restricted to a single locality. The aim of the present study was to investigate pollinator effectiveness of the different flower visitors to the terrestrial orchid Eulophia alta at three different localities and to analyse whether differences in pollinator abundance and composition effect this plant''s reproductive success.

Methods

Natural pollination was observed in vivo, and manipulative experiments were used to study the pollination biology and breeding system of E. alta at three sites near Manaus, Brazil. To gain a better understanding of the underlying mechanisms of pollinator attraction, nectar composition and secretion patterns were also studied, floral scent composition was analysed and a bioassay was conducted.

Key Results

Flower visitors, pollinator composition, pollinia transfer efficiency of particular pollinator species and natural fruit set differed among the investigated populations of E. alta. Flowers were self-compatible, partially autogamous and effectively pollinated by five bee species (four Centris species and Xylocopa muscaria). Visiting insects appeared to imbibe small amounts of hexose-rich nectar. Nectar sugar content was highest on the third day after flower opening. Floral fragrance analyses revealed 42 compounds, of which monoterpenes and benzenoids predominated. A bioassay using floral parts revealed that only floral tissue from the labellum chamber and labellum tip was attractive to flower visitors.

Conclusions

The data suggest that observed differences in reproductive success in the three populations cannot be explained by absolute abundance of pollinators alone. Due to behavioural patterns such as disturbance of effective pollinators on flowers by male Centris varia bees defending territory, pollinia transfer efficiencies of particular pollinator species also vary between study sites and result in differing reproductive success.     

Arabidopsis lyrata Small RNAs: Transient MIRNA and Small Interfering RNA Loci within the Arabidopsis Genus

Twenty-one-nucleotide microRNAs (miRNAs) and 24-nucleotide Pol IV-dependent small interfering RNAs (p4-siRNAs) are the most abundant types of small RNAs in angiosperms. Some miRNAs are well conserved among different plant lineages, whereas others are less conserved, and it is not clear whether less-conserved miRNAs have the same functionality as the well conserved ones. p4-siRNAs are broadly produced in the Arabidopsis genome, sometimes from active hot spot loci, but it is unknown whether individual p4-siRNA hot spots are retained as hot spots between plant species. In this study, we compare small RNAs in two closely related species (Arabidopsis thaliana and Arabidopsis lyrata) and find that less-conserved miRNAs have high rates of divergence in MIRNA hairpin structures, mature miRNA sequences, and target-complementary sites in the other species. The fidelity of miRNA biogenesis from many less-conserved MIRNA hairpins frequently deteriorates in the sister species relative to the species of first discovery. We also observe that p4-siRNA occupied loci have a slight tendency to be retained as p4-siRNA loci between species, but the most active A. lyrata p4-siRNA hot spots are generally not syntenic to the most active p4-siRNA hot spots of A. thaliana. Altogether, our findings indicate that many MIRNAs and most p4-siRNA hot spots are rapidly changing and evolutionarily transient within the Arabidopsis genus.