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Selected AbstractsEVOLUTION OF REPRODUCTIVE STRATEGIES IN THE SEXUALLY DECEPTIVE ORCHID OPHRYS SPHEGODES: HOW DOES FLOWER-SPECIFIC VARIATION OF ODOR SIGNALS INFLUENCE REPRODUCTIVE SUCCESS?EVOLUTION, Issue 6 2000Manfred Ayasse Abstract The orchid Ophrys sphegodes Miller is pollinated by sexually excited males of the solitary bee Andrena nigroaenea, which are lured to the flowers by visual cues and volatile semiochemicals. In O. sphegodes, visits by pollinators are rare. Because of this low frequency of pollination, one would expect the evolution of strategies that increase the chance that males will visit more than one flower on the same plant; this would increase the number of pollination events on a plant and therefore the number of seeds produced. Using gas chromatography-mass spectrometry (GC-MS) analyses, we identified more than 100 compounds in the odor bouquets of labellum extracts from O. sphegodes; 24 compounds were found to be biologically active in male olfactory receptors based on gas chromatography with electroantennographic detection (GC-EAD). Gas chromatography (GC) analyses of odors from individual flowers showed less intraspecific variation in the odor bouquets of the biologically active compounds as compared to nonactive compounds. This can be explained by a higher selective pressure on the pollinator-attracting communication signal. Furthermore, we found a characteristic variation in the GC-EAD active esters and aldehydes among flowers of different stem positions within an inflorescence and in the n-alkanes and n-alkenes among plants from different populations. In our behavioral field tests, we showed that male bees learn the odor bouquets of individual flowers during mating attempts and recognize them in later encounters. Bees thereby avoid trying to mate with flowers they have visited previously, but do not avoid other flowers either of a different or the same plant. By varying the relative proportions of saturated esters and aldehydes between flowers of different stem positions, we demonstrated that a plant may take advantage of the learning abilities of the pollinators and influence flower visitation behavior. Sixty-seven percent of the males that visited one flower in an inflorescence returned to visit a second flower of the same inflorescence. However, geitonogamy is prevented and the likelihood of cross-fertilization is enhanced by the time required for the pollinium deposited on the pollinator to complete its bending movement, which is necessary for pollination to occur. Cross-fertilization is furthermore enhanced by the high degree of odor variation between plants. This variation minimizes learned avoidance of the flowers and increases the likelihood that a given pollinator would visit several to many different plants within a population. [source] Characterization and expression analysis of the aspartic protease gene family of Cynara cardunculus L.FEBS JOURNAL, Issue 10 2007Catarina Pimentel Cardosin A and cardosin B are two aspartic proteases mainly found in the pistils of cardoon Cynara cardunculus L., whose flowers are traditionally used in several Mediterranean countries in the manufacture of ewe's cheese. We have been characterizing cardosins at the biochemical, structural and molecular levels. In this study, we show that the cardoon aspartic proteases are encoded by a multigene family. The genes for cardosin A and cardosin B, as well as those for two new cardoon aspartic proteases, designated cardosin C and cardosin D, were characterized, and their expression in C. cardunculus L. was analyzed by RT-PCR. Together with cardosins, a partial clone of the cyprosin B gene was isolated, revealing that cardosin and cyprosin genes coexist in the genome of the same plant. As a first approach to understanding what dictates the flower-specific pattern of cardosin genes, the respective gene 5, regulatory sequences were fused with the reporter ,-glucuronidase and introduced into Arabidopsis thaliana. A subsequent deletion analysis of the promoter region of the cardosin A gene allowed the identification of a region of approximately 500 bp essential for gene expression in transgenic flowers. Additionally, the relevance of the leader intron of the cardosin A and B genes for gene expression was evaluated. Our data showed that the leader intron is essential for cardosin B gene expression in A. thaliana. In silico analysis revealed the presence of potential regulatory motifs that lay within the aforementioned regions and therefore might be important in the regulation of cardosin expression. [source] Volatile constituents of the leaves and flowers of Hypericum triquetrifolium Turra,FLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2003Alessandra Bertoli Abstract The ,ower and leaf oil of Hypericum triquetrifolium Turra (Guttiferae, Hypericoideae) from Calabria (Italy) were studied by GC and GC,MS. The major components identi,ed in each oil were n -nonane (8%, 15%), , -pinene (8%, 4%), , -pinene (13%, 10%), myrcene (16%, 5%), , -caryophyllene (5%, 11%), germacrene-D (10%, 13%), sabinene (13%, 3%) and caryophyllene oxide (5%, 12%) in the leaf and ,ower oils, respectively. The aerial parts of the same plant were also analysed by SPME. The SPME analysis showed higher yields of undecane (14%, 10%) and , -caryophyllene (14%, 10%) in comparison with the corresponding hydrodistillation oils, in addition to , -pinene, , -pinene, sabinene and myrcene, amounting to (9%, 6%), (7%, 4%), (1%, 9%), (1%, 10%) for the leaves and ,owers, respectively. Copyright © 2003 John Wiley & Sons, Ltd. [source] The inhibition of paw oedema formation caused by the oil of Copaifera multijuga Hayne and its fractionsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2006Valdir F. Veiga Junior Two oils exuded from a Copaifera multijuga Hayne tree (Leguminosae-Caesalpinoideae), collected from the same plant, but in different periods of the year, and the hexanic, dichloromethanic and methanolic fractions of one of these oils were analysed by high-resolution gas chromatography (HRGC) and HRGC coupled with mass spectrometry (HRGC-MS). In addition, the in-vivo preliminary anti-oedematogenic actions of the oil and some fractions of it were assessed against carrageenan- and bradykinin-induced oedema formation in the rat paw. Twenty-seven sesquiterpenes and six diterpenes were identified, ,-caryophyllene, ,-copaene and copalic acid being the main components. The dichloromethanic and methanolic fractions obtained from C. multijuga oil given by the intraperitoneal route caused a significant inhibition of paw oedema caused by carrageenan with inhibition of 49 ± 13% and 64 ± 9 %, respectively. Likewise, dexamethasone (the positive control drug) also greatly inhibited carrageenan-induced paw oedema formation (60 ± 4% at 2 h). The hexanic fraction also significantly inhibited (50 ± 6%) the paw oedema formation caused by bradykinin. These results suggest the presence of still non-identified active terpene compounds in the oil of C. multijuga that exhibit anti-oedematogenic properties. Of note, the yield of these compounds and the pharmacological actions of the oil, exhibited great seasonal variations, a relevant aspect that should be carefully observed for the correct medicinal use of this plant by the population. [source] Acetylcholinesterase inhibitors from Stephania venosa tuberJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2006Kornkanok Ingkaninan Acetylcholinesterase (AChE) inhibitors have lately gained interest as potential drugs in the treatment of Alzheimer's disease. Three AChE inhibitors were isolated from tubers of a Thai medicinal plant, Stephania venosa (Bl) Spreng. They were identified as quaternary protoberberine alkaloids, stepharanine, cyclanoline and N -methyl stepholidine. They expressed inhibitory activity on AChE with IC50 values (concentration that caused 50% inhibition of activity) of 14.1K ± 0.81, 9.23 ± 3.47 and 31.30 ± 3.67 ,M, respectively. The AChE inhibitory activity of these compounds was compared with those of the related compounds, palmatine, jatrorrhizine and berberine, as well as tertiary protoberberine alkaloids isolated from the same plant, stepholidine and corydalmine. The results suggest that the positive charge at the nitrogen of the tetrahydroisoquinoline portion, steric substitution at the nitrogen, planarity of the molecule or substitutions at C-2, ,3, ,9, and ,10 affect the AChE inhibitory activity of protoberberine alkaloids. [source] Limitations to CO2 assimilation in ozone-exposed leaves of Plantago majorNEW PHYTOLOGIST, Issue 1 2002Y. Zheng Summary ,,The potential limitations on net leaf carbon assimilation imposed by stomatal conductance, carboxylation velocity, capacity for ribulose 1,5-bisphosphate regeneration and triose phosphate ultilization rate were derived from steady-state gas exchange measurements made over the life-span of two leaves on plants of an ,O3 -sensitive' population of Plantago major grown at contrasting atmospheric O3 concentrations. ,,Parallel measurements of chlorophyll fluorescence were used to monitor changes in the quantum efficiency of PSII photochemistry, and in vitro measurements of Rubisco activity were made to corroborate modelled gas exchange data. ,,Data indicated that a loss of Rubisco was predominantly responsible for the decline in CO2 assimilation observed in O3 -treated leaves. The quantum efficiency of PSII was unchanged by O3 exposure. ,,Stomatal aperture declined in parallel with CO2 assimilation in O3 -treated plants, but this did not account for the observed decline in photosynthesis. Findings suggested that O3 -induced shifts in stomatal conductance result from ,direct' effects on the stomatal complex as well as ,indirect effects' mediated through changes in intercellular CO2 concentration. Leaves on the same plant exposed to equivalent levels of O3 showed striking differences in their response to the pollutant. [source] From pollen dynamics to adaptive dynamicsPLANT SPECIES BIOLOGY, Issue 1 2000Tom J. De Jong Abstract On plants with many flowers, bumblebees tend to visit more flowers in sequence. This induces pollen transfer between flowers on the same plant (geitonogamy). Consequently, in self-compatible plants the selfing rate increases with the number of simultaneously open flowers on the plant, and pollen export to other plants in the population can be a decelerating function of the number of flowers. I argue that geitonogamy is important in relation to two phenomena. First, it may explain the low number of seeds per flower and the size-dependent sex allocation observed in some species. Applying sex allocation theory to the boraginaceous Cynoglossum officinale and Echium vulgare shows that hermaphroditism is stable in both species. The predicted evolutionarily stable values for seeds per flower are close to observed values in the field. The model generally predicts that seeds per flower increase with plant size. This prediction is fine for C. officinale but E. vulgare defies the theory. Second, geitonogamy is important in the evolution of dioecy, as already suggested by Darwin. With abiotic pollination the export of pollen to other plants is likely to be proportional to the number of flowers produced, while it decelerates in animal-pollinated plants. Dioecy can then evolve gradually in a species with abiotic pollination, provided that inbreeding depression exceeds 50%, geitonogamous selfing increases with the number of flowers and that genetic variation exists. With complete pollen discounting as in the models of geitonogamous pollination by animals, hermaphroditism is always stable. The model explains Darwin's observation that dioecy is more common in wind-pollinated species and in species in which individuals are large, reproducing with many flowers. [source] Experimental tests of the function of mirror-image flowersBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2005LINLEY K. JESSON Enantiostyly, the reciprocal deflection of the style to the left or right side of the floral axis has evolved independently in at least a dozen angiosperm families. Unlike other plant sexual polymorphisms, the adaptive significance of these mirror-image flowers remains unclear. Most authors have interpreted enantiostyly as a floral mechanism that promotes cross-pollination. However, any functional interpretation is complicated by the fact that enantiostyly occurs in two forms. In monomorphic enantiostyly there are left- and right-styled flowers on the same plant, while in dimorphic enantiostyly they are on separate individuals. In this paper we develop a model of pollen transfer which indicates that monomorphic enantiostyly should reduce geitonogamous pollination compared to a non-enantiostylous condition, and that the lowest levels of geitonogamous pollination should occur in dimorphic enantiostyly. We tested these predictions using floral manipulations of bee-pollinated Solanum rostratum in garden arrays. We compared mating patterns and fertility in five array types: non-enantiostylous and straight-styled, monomorphic enantiostylous, dimorphic enantiostylous, and arrays uniform for either left or right stylar deflection. Outcrossing rates in non-enantiostylous arrays (t = 0.33 ± 0.04) were significantly lower than all other arrays, while monomorphic enantiostylous arrays (t = 0.74 ± 0.06) had significantly lower outcrossing rates than dimorphic enantiostylous arrays (t = 0.88 ± 0.04) and those uniform for stylar deflection (t = 0.84 ± 0.04). In dimorphic enantiostylous arrays, intermorph pollen transfer accounted for 75% of all outcrossing events. In pollen-limited situations, both types of enantiostylous arrays had significantly higher female fertility than arrays fixed for one direction, demonstrating that enantiostyly promotes pollen transfer between flowers of opposite stylar orientation. Our results provide support for the hypothesis that enantiostyly functions to increase the precision of cross-pollination in bee-pollinated plants by reducing geitonogamy. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 167,179. [source] New (9,H)-Lanostanes and Lanostanes from Mikania aff. jeffreyi (Asteraceae)CHEMISTRY & BIODIVERSITY, Issue 9 2009Carla Abstract Four new (9,H)-lanostanes, i.e., (9,H)-3, -acetoxylanosta-7,24-diene, (9,H)-3-oxolanosta-7,24-diene, (9,H,24R)-3, -acetoxy-24-hydroxylanosta-7,25-diene, and (9,H,24S)-3, -acetoxy-24-hydroxylanosta-7,25-diene, two new lanostanes, i.e., (24R)-3, -acetoxy-24-hydroxylanosta-8,25-diene and (24S)-3, -acetoxy-24-hydroxylanosta-8,25-diene, and two known lanostanes, i.e., 3, -acetoxylanosta-8,24-diene and 3-oxolanosta-8,24-diene, were obtained from a new Mikania species (Asteraceae) besides pentacyclic triterpenes, steroids, and diterpenes. The structures of the compounds were determined by spectroscopic methods. This is the second study about acetyl-lanosterols from higher plants. Moreover, (9,H)-lanostanes are very rare metabolites from dicotyledone angiosperms. The occurrence of these terpenes together in the same plant makes the species a good source for lanostane- and (9,H)-lanostane-biosynthesis studies. [source] Evaluation of Transgenic Poplars Over-Expressing Enzymes of Glutathione Synthesis for Phytoremediation of CadmiumPLANT BIOLOGY, Issue 6 2002A. Koprivova Abstract: Recently, phytoremediation of soils polluted with heavy metals has received a lot of attention. Since glutathione (GSH) and its derivatives (e.g., phytochelatins) play a major role in plant defence against environmental pollutants, we tested the effects of over-expression of bacterial genes for GSH synthesis in poplar on cadmium accumulation. A pilot experiment with CdCl2 in hydroponics revealed that poplars over-expressing ,-glutamylcysteine synthetase (,-ECS) accumulated significantly more Cd in root tissue than wild type or glutathione synthetase over-expressing poplars. To test the partitioning of Cd in different organs, poplar lines over-expressing ,-ECS in the cytosol and in chloroplasts were treated with 0.2 mM CdCl2 in hydroponics. Significant amounts of Cd were translocated to leaves, but significant differences in Cd accumulation were not observed between transgenic and wild type plants. To evaluate these lines for large-scale phytoremediation of cadmium, plants were treated with 2 mM Cd in soil. Over a four-week period, the poplar plants were able to accumulate up to 5.3 mg Cd. Most remarkably, in young leaves of both transgenic lines, Cd was accumulated to concentrations 2.5 - 3 times higher than in the wild type. The increased allocation of cadmium to the young leaves represents a potentional advantage for the phytoremediation process using the same plants over several vegetation periods. The use of transgenic poplar lines with enhanced glutathione production capacity seems to be of particular advantage in highly polluted soils. [source] Cultivar preference exhibited by two sympatric and genetically distinct populations of the soybean fungal pathogen Phialophora gregata f.sp. sojaePLANT PATHOLOGY, Issue 2 2005X. Meng Phialophora gregata f.sp. sojae, a soilborne vascular pathogen causing brown stem rot of soybean, has been divided into A and B populations based on variation in the intergenic spacer region of nuclear rDNA (rDNA marker). The A and B populations correlate with defoliating and nondefoliating pathotypes, respectively. In this study, eight additional polymorphic anonymous marker loci (five inter simple sequence repeat loci and three long-primer random amplified polymorphic DNA loci) were identified and applied to a total of 189 isolates. Alleles of these eight loci were invariant within, but different between the A and B populations, providing further evidence that the rDNA marker identifies genetically distinct populations. The two populations were sympatric, residing not only in the same field, but also in the same plants under field conditions. Representative strains of the two populations, when used individually in inoculations, infected both resistant cv. Bell and susceptible cv. Sturdy. However, when the same representatives of the two populations were mixed in a 1 : 1 ratio and used as a mixed inoculum in a competitive bioassay, differential cultivar preference was revealed using PCR detection of populations in infected plants. Population A was detected significantly more often (18 out of 24 plants) in the susceptible cv. Sturdy, whereas population B was detected significantly more often (17 out of 24 plants) in the resistant cv. Bell, corroborating earlier field studies. This is the first controlled experiment to demonstrate a differential host preference of P. gregata f.sp. sojae toward different cultivars of the same host species. Unification of terminologies used in P. gregata f.sp. sojae is discussed. [source] SlCCD7 controls strigolactone biosynthesis, shoot branching and mycorrhiza-induced apocarotenoid formation in tomatoTHE PLANT JOURNAL, Issue 2 2010Jonathan T. Vogel Summary The regulation of shoot branching is an essential determinant of plant architecture, integrating multiple external and internal signals. One of the signaling pathways regulating branching involves the MAX (more axillary branches) genes. Two of the genes within this pathway, MAX3/CCD7 and MAX4/CCD8, encode carotenoid cleavage enzymes involved in generating a branch-inhibiting hormone, recently identified as strigolactone. Here, we report the cloning of SlCCD7 from tomato. As in other species, SlCCD7 encodes an enzyme capable of cleaving cyclic and acyclic carotenoids. However, the SlCCD7 protein has 30 additional amino acids of unknown function at its C terminus. Tomato plants expressing a SlCCD7 antisense construct display greatly increased branching. To reveal the underlying changes of this strong physiological phenotype, a metabolomic screen was conducted. With the exception of a reduction of stem amino acid content in the transgenic lines, no major changes were observed. In contrast, targeted analysis of the same plants revealed significantly decreased levels of strigolactone. There were no significant changes in root carotenoids, indicating that relatively little substrate is required to produce the bioactive strigolactones. The germination rate of Orobanche ramosa seeds was reduced by up to 90% on application of extract from the SlCCD7 antisense lines, compared with the wild type. Additionally, upon mycorrhizal colonization, C13 cyclohexenone and C14 mycorradicin apocarotenoid levels were greatly reduced in the roots of the antisense lines, implicating SlCCD7 in their biosynthesis. This work demonstrates the diverse roles of MAX3/CCD7 in strigolactone production, shoot branching, source,sink interactions and production of arbuscular mycorrhiza-induced apocarotenoids. [source] | |||||||||||||