Early blooming's challenges: extended flowering season, diverse pollinator assemblage and the reproductive success of Gynodioecious Daphne laureola.
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BACKGROUND AND AIMS: The scarcity and unpredictability of active pollinators during late winter in temperate areas tends to favour extended flowering seasons and increased floral longevity in early blooming species, which are usually pollinated by diverse sets of insects. Daphne laureola is a gynodioecious woody perennial that flowers from January to April in southern Spain, a period characterized by cold temperatures, frequent rains and irregular snowfalls. METHODS: Pollinators were excluded at four different times during the flowering season in order to determine the effect of decreased exposure to pollinators on fruit set in female and hermaphrodite individuals. The role of nocturnal and diurnal pollination on reproductive success in each gender was simultaneously evaluated by selective exclusion. KEY RESULTS: A 50 % reduction in the flowering period decreased fruit set of females by 50 %, whereas the corresponding decrease in self-compatible hermaphrodites was only approx. 25 %. Day-active hymenopterans and lepidopterans were infrequent visitors, and nocturnal pollinators were inefficient, suggesting that pollen beetles, Meligethes elongatus, were the main pollinators of D. laureola in the study region. CONCLUSIONS: Beetles were less abundant in pollenless females, although discrimination did not apparently result in pollination limitation of female reproduction. A preference of beetles for sunny locations emphasized the relevance of abiotic conditions for pollination of this early blooming shrub. (+info)
Mating system, sex ratio, and persistence of females in the gynodioecious shrub Daphne laureola L. (Thymelaeaceae).
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Although in gynodioecious populations male steriles require a fecundity advantage to compensate for their gametic disadvantage, southern Spanish populations of the long-lived shrub Daphne laureola do not show any fecundity advantage over hermaphrodites in terms of seed production and early seedling establishment. By using allozyme markers, we assess the mating system of this species in five populations differing in sex ratio, and infer levels of inbreeding depression over the whole life cycle by comparing the inbreeding coefficients at the seed and adult plant stages. Extremely low outcrossing rates (0.001+info)
Daphnogirins A and B, two biflavones from Daphne giraldii.
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Two new biflavonoids, daphnogirins A (1) and B (2), were obtained from the roots of Daphne giraldii. Their structures were established on the basis of the spectral data and X-ray diffraction data of the co-crystal of 1 and 2. Daphnogrins A and B have the same configuration at C-1 and opposite configurations at C-16 and C-17. Oxygen radical scavenging assay has indicated that they are of significant antioxidative activity. (+info)
Ecological context of breeding system variation: sex, size and pollination in a (predominantly) gynodioecious shrub.
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BACKGROUND AND AIMS: Species that exhibit among-population variation in breeding system are particularly suitable to study the importance of the ecological context for the stability and evolution of gender polymorphism. Geographical variation in breeding system and sex ratio of Daphne laureola (Thymelaeaceae) was examined and their association with environmental conditions, plant and floral display sizes, and pollination environment in a broad geographic scale was analysed. METHODS: The proportion of female and hermaphrodite individuals in 38 populations within the Iberian Peninsula was scored. Average local temperature and precipitation from these sites were obtained from interpolation models based on 30 years of data. Pollination success was estimated as stigmatic pollen loads, pollen tubes per ovule and the proportion of unfertilized flowers per individual in a sub-set of hermaphroditic and gynodioecious populations. KEY RESULTS: Daphne laureola is predominantly gynodioecious, but hermaphroditic populations were found in northeastern and southwestern regions, characterized by higher temperatures and lower annual precipitation. In the gynodioecious populations, female plants were larger and bore more flowers than hermaphrodites. However, due to their lower pollination success, females did not consistently produce more seeds than hermaphrodites, which tends to negate a seed production advantage in D. laureola females. In the northeastern hermaphroditic populations, plants were smaller and produced 9-13 times fewer flowers than in the other Iberian regions, and thus presumably had a lower level of geitonogamous self-fertilization. However, in a few southern populations hermaphroditism was not associated with small plant size and low flower production. CONCLUSIONS: The findings highlight that different mechanisms, including abiotic conditions and pollinator service, may account for breeding system variation within a species' distribution range and also suggest that geitonogamy may affect plant breeding system evolution. (+info)
Two new bis-coumarin glycosides from Daphne giraldii NITSCHE.
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Two new bis-coumarin glycosides were isolated from the stem barks of Daphne giraldii NITSCHE. Their structures were elucidated as 6-O-alpha-L-rhamnnopyranosyl daphnogirin (1), and 6-O-beta-D-apiofuranosyl daphnogirin (2), on the basis of detailed spectroscopic analysis. Compounds 1 and 2 were tested inhibitory effects against production of nitric oxide (NO) in RAW264.7 cells, and cytotoxicity of human tumor cell lines A549, LOVO, QGY-7703, 6T-CEM. The results showed that compounds 1 and 2 neither reduced production of NO, nor inhibited human tumor cell lines. (+info)
Biflavonoids from Daphne feddei and their inhibitory activities against nitric oxide production.
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Bioassay-directed fractionation led to the isolation of two new biflavonoids and 13 known biflavonoids from a sample of the dried stem barks of Daphne feddei. The structures of compounds 1 and 2 were elucidated as 2''-methoxy-daphnodorin C (1) and 2''-methoxy-2-epi-daphnodorin C (2) on the basis of detailed spectroscopic analysis and X-ray crystallography. All 15 biflavonoids were tested for inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages. Compounds 1, 2, 8, 10, 14 and 15 showed varying degrees of inhibitory activities against the production of NO in tested concentration of 25, 50, 75 and 100 microg/ml. (+info)
Attraction of female grapevine moth to common and specific olfactory cues from 2 host plants.
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Daphnane diterpene esters with anti-proliferative activities against human lung cancer cells from Daphne genkwa.
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Two new daphnane-type diterpene esters, yuanhuahine (1) and yuanhualine (2), were isolated from the flowers of Daphne genkwa (Thymelaeaceae) along with three known diterpene esters, yuanhuacine (3), yuanhuadine (4), and yuanhuagine (5). Their structures were determined by a combination of 1D and 2D NMR experiments, including correlation spectroscopy (COSY), heteronuclear multiple quantum correlation (HMQC), heteronuclear multiple bond correlation (HMBC), and rotating frame Overhauser enhancement spectroscopy (ROESY) sequences, and mass spectrometry. All the isolated compounds were tested against A549 human lung cancer cells and MRC-5 human normal lung epithelial cells. Compounds 1-5 exhibited potent anti-proliferative effects against A549 lung cancer cells with IC(50) values of 12-53 nM, whereas these compounds were relatively non-cytotoxic against MRC-5 normal lung epithelial cells. (+info)