Tetrahydrofuran-type terpenoids from Tanacetum vulgare

Investigation of a rare genotype of Tanacetum vulgare afforded a series of tetrahydrofuran-type terpenoids, whose pattern was different in flowers and leaves. The major constituent of the flowers was the trans Δ^3,4-hydroperoxide of davanone, whereas the leaves gave mostly a peroxyhemiketalic compound resulting from the intramolecular cyclization of the cis Δ^3,4-hydroperoxide of davanone. Structures were elucidated by spectral data and chemical reactions, including correlation with natural (+)-davanone. The peroxyhemiketalic compound upon acylation of its hydroxyl group gave an instantaneous complex reaction, resulting in the formation of a β-acyloxyenone and loss of one molecule of acetone. Among the minor constituents of the leaves, a C-10 carboxylic acid biogenetically related with davanone was isolated.     

Volatiles associated with different flower stages and leaves of Acacia cyclops and their potential role as host attractants for Dasineura dielsi (Diptera: Cecidomyiidae)

Acacia cyclops (Fabaceae) is an Australian species which was introduced into South Africa in the nineteenth century. Because of its invasive status in South Africa, a gall midge, Dasineura dielsi (Diptera: Cecidomyiidae), was released in 2001 in order to impact its reproduction by inducing galls on the flowers and thereby preventing seed set. Nothing is known about the cues used by D. dielsi for locating its host flowers. As part of an initial investigation into whether or not chemical cues might play a role in host finding, we analysed headspace samples of Acacia cyclops volatiles from leaves and reproductive parts at different stages (early bud, late bud, early flowering, and senescing flowering stages) using gas chromatography–mass spectrometry (GC–MS). In total, 72 different compounds were detected of which 62 were identified. The analyses showed that open flowers, the stage used by D. dielsi for oviposition, and yellow buds had similar odour compositions with (Z)-3-hexen-1-ol acetate, 4-oxoisophorone, (Z)-β-ocimene, an unknown aliphatic compound, heptadecane, and nonadecane dominating in open flowers. Leaf volatiles were distinct from those in the reproductive plant parts by their high relative amount of (Z)-β-ocimene. (Z)-3-Hexen-1-ol acetate had its maximum relative amount in the green bud samples and was much lower in the later floral stages. In contrast, 4-oxoisophorone peaked in yellow buds and open flowers with little or none of it found in younger or older stages. The volatile compounds of the different flower stages and leaves are discussed in relation to their potential role as attractants used by the biocontrol agent D. dielsi to locate its host plant.     

Characterisation of the effects of leaf galls of Clusiamyia nitida (Cecidomyiidae) on Clusia lanceolata Cambess. (Clusiaceae): Anatomical aspects and chemical analysis of essential oil

Galls develop in different plant organs and are induced by the activity of various organisms. Some studies have investigated the ecological interactions between species of Clusia and gall-inducing insects. The goal of our study is to characterise changes in leaf anatomy caused by the activity of gall insects in Clusia lanceolata. Additionally, we also investigated the chemical composition of volatile compounds of normal leaves and those with galls to detect possible effects on the host plants. For anatomical studies, we used botanical material fixed in FAA₅₀. Transversal sections of the leaf blade were obtained from samples of leaves located on the third and fourth nodes from both male and female individuals. Material was studied from both sexes both with unaffected leaves and leaves containing galls. Fresh leaves of C. lanceolata were used for the extraction of volatile compounds, which were submitted to stem distillation using a modified Clevenger apparatus determining the oil yields subsequently (w/w). The unaffected leaves of female and male individuals of C. lanceolata exhibit similar anatomical structures. However, galls on leaves of both sexes show anatomical differences. The activity of the gall insect Clusiamyia nitida induces several changes in the foliar anatomy and the distribution of metabolic compounds in new tissues during gall development. However, the larvae are not able to induce significant changes in the volatile compounds of inflected leaves from male and female individuals.     

Epiphytic Occurrence of Azorhizobium caulinodans and Other Rhizobia on Host and Nonhost Legumes

A large population of Azorhizobium caulinodans was present on Sesbania rostrata; up to 5 × 10⁻⁵ cm⁻² were found on leaves and fewer were found on flowers. Although A. caulinodans was also present on the leaves of Sesbania aculeata (nonhost), the populations were much smaller than that observed on S. rostrata. The population of S. aculeata rhizobia on host leaves was less than 30 cm⁻², and their presence on host flowers was sporadic. Aeschynomene afraspera and Aeschynomene aspera rhizobia, which are profusely stem nodulating, were found on the leaves of host and nonhost plants and on the flowers of host plants, but, Aeschynomene pratensis and Aeschynomene sensitiva rhizobia were not found on the leaves and flowers of host plants.     

Effect of development on monoterpene composition of Hedeoma drummondii

Samples of leaves, flowers and whole plants were taken from clonal stock of Hedeoma drummondii to determine the effect of developmental age on the monoterpene profile. GLC analysis revealed that there are significant differences in the quantity of major monoterpenes in leaves and flowers of different ages and in plants at different flowering stages. The results are discussed in relation to biogenetic pathways and implications for taxonomic work.     

Flavonoids in Parahebe and Veronica: a chemosystematic study

Flavone glycosides are the main flavonoid leaf constituents in the related genera Parahebe and Veronica (Scrophulariaceae), in agreement with former chemical studies of the family. In Parahebe there are groups of species in which there are mainly luteolin glycosides, and groups in which 6-hydroxyluteolin dominates. Small amounts of apigenin occur in many taxa. Glycosylation is usually in the 7-position but 4′- and 5-glycosides were also found. In Veronica a larger variety of flavone aglycones was found: e.g. luteolin, apigenin, chrysoeriol, tricin and three different 6-hydroxyflavones. They are often present in the plants in the form of glucuronides. Glycosylation is in the 7-or-5-position. Most species of both genera have a distinctive pattern of flavonoid glycosides in their leaves which can be used for identification. Populations of P. catarractae are an exception in showing three different patterns, but here the variety in flavone profiles corresponds to the pattern of morphological and geographic variation within this taxon. Anthocyanins are responsible for the blue, mauve and pink colours of the flowers in the two genera. In Veronica they are based on delphinidin, whereas in Parahebe catarractae on both delphinidin and cyanidin.     

Fatty acid changes in Althaea rosea tissues during growth

Lipids were isolated from roots, stems, leaves, buds, flowers seeds of Althaea rosea plants at different stages of growth. The lipid contents of al     

The effect of light quality on leaf production and development of in vitro-cultured plants of Alternanthera brasiliana Kuntze

We investigated the influence of light quality on the leaf development of Alternanthera brasiliana Kuntze (Amaranthaceae) grown in vitro. Growth parameters including specific leaf mass, thickness, and leaf density were lowest in plants grown under red light. Blue light induced the largest number of leaves/plant, and the largest thickness and area of the leafblade. Green and red lights induced the smallest leaf areas. The thickness of the abaxial-face epidermis and spongy parenchyma of the plants was significantly reduced in plants grown under red light. The thickness of the palisade parenchyma and upper epidermis were significantly increased in plants grown under blue light, compared to the other fluorescent-light treatments. The specific spectral band also influenced the differentiation of mesophyll cells. In the dark and under red light, the mesophyll was homogenous; and in the dark and under green light, the leaves were more compact. Under blue light, the cells displayed the characteristic palisade morphology. The results showed that the increase of a specific parenchyma type was related to a specific spectral band. All spectral-quality treatments reduced the numbers of stomata and trichomes. The results for green light were in some respects similar to those for red light, and in other respects similar to those for blue light, probably because phytochromes and cryptochromes are green-light receptors. This study indicated that Alternanthera plants have strong morphological plasticity induced by light. The results suggest that high-quality Alternanthera can be achieved by culturing the plants in vitro under a combination of blue and red light.     

Flower colour preferences of Aporia bieti (Lepidoptera: Pieridae) in the Xiama Forest Farm,Gansu, China

In addition to their ornamental value, butterflies provide value to flowering plants through pollination, which can improve their heterosis. Studying the relationship between butterflies and flowers is useful for understanding the adaptive relationship between them. By observing the pollinating and feeding behaviour of Aporia bieti in the Xiama forest, Gansu, we explored the adaptive relationship between A. bieti proboscis size and the corolla tube length of the flowers. To eliminate interference from the butterfly's sense of smell, we used foam flowers instead of real flowers. The results indicated that (1) of the red, yellow, pink, purple, and white flowers tested, yellow flowers were preferred; (2) there was no distinct difference in the preferences of A. bieti for large- (45 mm) and small- (25 mm) sized flowers; and (3) A. bieti proboscis length was significantly related to the corolla tube length of the flowers fed on by the butterfly, which suggests co-evolution between butterfly proboscis length and the length of the pollen tube.     

First records of flower biology and pollination in African Annonaceae: Isolona, Piptostigma, Uvariodendron, Monodora and Uvariopsis

Seven species from five genera of Annonaceae were studied with regard to their flower biology and pollination in the Southwest Province of Cameroon, West Africa. They have protogynous hermaphroditic flowers, with exception of Uvariopsis species, which are monoecious. Fused petals of Isolona campanulata remain apically spreading and open during anthesis but form a deep basal urceolate tube around the reproductive organs. At anthesis the yellow pendent flowers emit a fruit-like scent and attracted small beetles, the likely pollinators. Piptostigma sp. flowers also emit a fruit-like scent but provide a closed pollination chamber formed by the three inner petals. Small staphylinid beetles attracted during the female stage of anthesis are released from the flowers at the end of the male stage 2-3 days later. Both species have diurnal anthesis, attracting and releasing the flower visitors during daytime. In contrast, Uvariodendron connivens and U. calophyllum have nocturnal anthesis with floral thermogenesis, produce spicy, aromatic and fruity scents and attract large Scarabaeidae beetles, the pollinators, along with many curculionid beetles, which were principally predators of the thick petals. The very large flowers of Monodora tenuifolia have yellowish petals which are spotted with dark red markings. Together with the sweetish, slightly disagreeable scent the flowers attract flies, principally dung flies. The two investigated Uvariopsis species are monoecious with pistillate and staminate flowers being functional at the same time. The violet red flowers of U. bakeriana visually seem to mimic the fruiting body of certain stinkhorn fungi (Phallaceae) although without producing their strong unpleasant carcass stench. Flower-visiting dung flies were rare. Conversely, U. congolana has a strong fungus-like scent, its flowers are presented at litter height and dung flies living in the litter were the flower visitors, albeit sporadic. The 4-5 days lasting anthesis of both Uvariopsis species appears to be an evolutionary consequence of their diffuse pollinator spectra. The studied African Annonaceae therefore have either cantharophilous or myiophilous/sapromyiophilous flowers with, in part, respectively, remarkably long anthesis, thermogenesis, and widely open, large flowers - all attributes unknown or rare in the hitherto better studied Neotropical Annonaceae.     

Eco-coenotic conditions and structure of Trollius europaeus L. populations in an extrazonal habitat complex (Transylvanian Carpathian foothills)

To estimate the importance of community structure and environmental factors for maintenance and in situ conservation of populations of European Globeflower (Trollius europaeus subsp. europaeus) in four sites (one within a natural reserve) in a low elevation but cool valley of the Transylvanian Carpathian foothills, an inventory of all globeflower individuals was performed and floristic relevés were recorded in different community types (meadow, fen and scrub). As a surrogate for habitat conditions, we used plant species indicator values for light, moisture and nitrogen. Globeflower density is highest in mesic habitats, the ecological optimum estimated (about 6 on Ellenberg's scale) being slightly lower than that indicated for Central Europe (7). The juvenile:fertile plants ratio (J:F) declines with increasing soil moisture. Larger flower production in hygrophilous communities does not result in a higher proportion of juveniles or J:F ratio. Despite the presumed strong competition determined by high species richness in some host communities, the most dynamic population (large proportion of juveniles) was found in mesophilous, mown meadows. A clumped distribution of fertile plants under the open scrub canopy seems to be responsible for the significantly larger number of flowers per individual observed, as compared with the relative amount of flowers produced in the adjacent sward. Irrespective of host community, the juveniles display an aggregated distribution with respect to fertile plants, which is probably related to short-distance dispersal of seeds. Our results reveal the importance of host community species richness and soil moisture for the target population stage structure and reproductive investment.     

Nymphal performance correlated with adult preference for flowering host plants in a polyphagous mirid bug, Apolygus lucorum (Heteroptera: Miridae)

Apolygus lucorum (Heteroptera: Miridae), a polyphagous mirid bug, often shows a strong preference for flowering host plants. It is hypothesized that host plant selection by phytophagous insects results in a variety of behavioral trade-offs. In this study, the relationship between adult preference and nymphal performance was examined on host plants with their flowers left intact and with flowers removed to investigate potential trade-offs in A. lucorum’s preference for flowering plants. Field trials in 2010 and 2011 showed that adults and nymphs were significantly more abundant on plants with flowers left intact than on those with flowers removed, while oviposition choice trials in field cages revealed that female adults preferred to lay eggs on plants with flowers. Laboratory performance trials demonstrated that adult lifespan and fecundity and nymphal development rate and survival were all significantly higher on plants with flowers compared with plants without flowers. In contrast, sex ratio was not significantly different. Simple linear regression analysis showed positive correlations between (1) adult and nymphal abundances in the field, (2) nymphal development rates and survival with adult fecundity in the laboratory, and (3) adult lifespan with fecundity in the laboratory. Since a positive preference–performance correlation was found for A. lucorum, we conclude that there are no evident behavioral trade-offs for host plant selection by this polyphagous mirid bug.     

Changes in the endopolyploidy pattern of different tissues in diploid and tetraploid Phalaenopsis aphrodite subsp. formosana (Orchidaceae)

Endopolyploidy is frequently observed during development in plant species. Patterns of endopolyploidy are diverse in the various organs of different plant species. However, little is known about the role of endopolyploidization and its significance in orchids. This study was undertaken to determine the extent of endopolyploidy in different tissues of the diploid and tetraploid genotypes of Phalaenopsis aphrodite subsp. formosana and to examine the factors that contribute to increased ploidy levels. Endopolyploidy occurs in various tissues of diploid and tetraploid orchids, at different developmental stages and under different culture conditions, as determined by flow cytometry. In this study, different patterns of endopolyploidy were observed in parts of the protocorms, leaves, roots and flowers. Endopolyploidy was found in all tissues studied except the pollinia and the tetraploid ovaries. A higher degree of endopolyploidy was observed in mature tissues compared to young tissues, greenhouse-grown plants compared to in vitro plants and diploid plants compared to tetraploid plants. We discuss the relationships between endopolyploidization and several factors related to plant growth, as well as some practical considerations of these findings.     

内生真菌感染对宿主羊草抗病性的影响

以感染内生真菌的天然禾草羊草为实验材料,通过体外纯培养条件下的内生真菌、感染内生真菌的离体叶片和在体叶片对3种病原菌的抑菌实验,以探讨内生真菌对宿主植物羊草在抗病性方面的贡献。结果表明:体外纯培养条件下,分离自羊草的内生真菌Epichlobromicola对新月弯孢(Curvularia lunata)、根腐离蠕孢(Bipolaris sorokiniana)和枝孢霉(Cladosporium sp.)这3种病原菌都具有抑制作用,抑菌率分别达56.22%,46.93%和45.15%,且内生真菌培养滤液可以有效抑制这3种病原菌的孢子萌发,平均萌发率分别为30.4%,15.7%和16.4%;宿主植物叶片在离体条件下,内生真菌感染可以有效降低羊草叶片受C.lunata和C.sp.侵染后的病斑数或病斑长度,但对B.sorokiniana不起作用,甚至提高了叶片的病斑数及病斑长度,而离体叶片提取液对不同病原菌均有不同程度的抑制作用;在体条件下,内生真菌均可以通过降低叶片病斑数来增强羊草植株对这3种病原菌的抗性。由此看来,内生真菌E.bromicola对宿主植物羊草在抗病原菌侵染方面有一定的增益作用。     

An olfactory receptor from Apolygus lucorum (Meyer-Dur) mainly tuned to volatiles from flowering host plants

Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is one of the most serious agricultural pests, feeding on a wide range of cultivated plants, including cotton, cereals and vegetables in the north of China. This insect can frequently switch between habitats and host plants over seasons and prefer plants in bloom. A. lucorum relies heavily on olfaction to locate its host plants finely discriminating different plant volatiles in the environment. Despite its economical importance, research on the olfactory system of this species has been so far very limited. In this study, we have identified and characterized an olfactory receptor which is sensitively tuned to (Z)-3-Hexenyl acetate and several flowering compounds. Besides being present in the bouquet of some flowers, these compounds are produced by plants that have suffered attacks and are supposed to act as chemical messengers between plants. This OR may play an important role in the selection of host plants.     

Population dynamics and life history adaptations of Littorina neglecta Bean in an eelgrass meadow (Zostera marina L.) in Nova Scotia

The density of Littorina neglecta Bean from an eelgrass meadow in Nova Scotia was highest in mid-summer (July 1979; 45059 per m²) but fell rapidly during late summer and early autumn due to high mortality of new recruits and two year old individuals. Density remained constant until the following spring when it increased, due to movement of some adults into the study area and the release of young by females (up to ≈ 34000 per m²). During most of the year individuals were found on vegetation (live and dead eelgrass and drift algae) but nearly all moved down to the mud surface during winter to avoid ice (up to 25 cm thick) which was present from December to early March. Movement of ice was not a source of mortality for L. neglecta. Size-frequency histograms showed distinct cohorts and it was possible to follow the growth of year classes. Maximum age was 3 yr and maximum shell height was 4.56 mm. Males and females matured when 1 yr old at 1.7 and 1.8 mm shell height respectively. Size-specific fecundity was very high for such a small littorinid. These life history attributes appeared to be related to the low probability of survival to the maximum age. L. neglecta consumed epiphytes and detrital particles from the surface of eelgrass leaves, and the proportion of eelgrass plants with epiphytes was always low. Grazer exclusion experiments showed that L. neglecta controlled the amount of epiphytes and detritus on eelgrass leaves, and the population thus had a limited food supply. There were significant positive relations between surface area of plants and the numbers of adult and 0 + aged L. neglecta during summer and at that time 0 + individuals were restricted to the base of plants where epiphyte biomass was lowest. Post-recruitment mortality was probably related to intraspecific competition for food. Predation by a naticid gastropod probably accounted for much of the mortality of 2 + aged individuals. L. neglecta has a major positive influence on the growth of eelgrass and probably contributes significantly to nutrient recycling in the eelgrass community.     

将安龙花转移至马蓝属(爵床科)的形态特征依据

比较了安龙花(Dyschoriste sinica H. S. Lo)的模式标本与距药花属(Dyschoriste Nees)和马蓝属(Strobilanthes Bl.)部分种类的花粉和花的特征后,支持将安龙花转移到马蓝属,组合为Strobilanthes sinica (H. S. Lo) Y. F. Deng。安龙花隶属于马蓝属黄猄草群,它与日本马蓝(Strobilanthes japonica (Thunb.) Miq.)近似,但区别在于它的匍匐习性,叶矩圆状椭圆形,近无柄,花单生叶腋。因此,距药花属(Dyschoriste Nees)在中国并没有分布。     

Pathogenicity and Host Specificity of Mycovellosiella lantanae var. lantanae,a Potential Biocontrol Agent for Lantana camara in South Africa

Lantana camara is a poisonous, bushy shrub from South and Central America that has invaded much of the moist, warm sub-tropical areas of South Africa. In the last decade, evidence of a conspicuous and damaging mycobiota on lantana in the Neotropics has persuaded biocontrol researchers to consider fungi as potential biocontrol agents for this plant. Samples of diseased L. camara leaves were collected during field surveys in South, North and Central America from 1987 to 1997. Pathogenicity tests showed the leaf spot fungus, Mycovellosiella lantanae var. lantanae to be a promising biocontrol pathogen. Inoculations onto South African biotypes of L. camara and a number of closely related species within the family Verbenaceae were made under quarantine conditions to determine the pathogenicity and host specificity of the fungus. Inoculation of L. camara biotypes resulted in necrotic, grey lesions (20-60 per leaf), necrosis of flower buds and stalks, as well as defoliation of certain biotypes after three weeks. None of the other plant species tested showed any disease symptoms. This indicates a very restricted host range, making this pathogen a suitable candidate for application as a biological control agent. It is expected that the fungus will reduce the vigour and reproductive potential of L. camara. Due to the variation in virulence of M. lantanae var. lantanae when tested on South African lantana biotypes, release strategies may include the use of combinations of the isolates to target a wider range of lantana biotypes in the field. Permission to release M. lantanae var. lantanae in South Africa was granted in September 2001. The pathogen will be released as a classical biocontrol agent in South Africa.