Spectrophotometric analysis of nectar production in Silene vulgaris (Caryophyllaceae)

Significant differences in nectar content were observed between hermaphrodite and female plants of the gynomonoecious-gynodioecious taxon, Silene vulgaris, from populations in northern lower Michigan. These differences in nectar sugar content were observable with a carbohydrate digestion technique involving sulfuric acid, phenol, and measurement of the color change with a spectrophotometer. A hand-held refractometer did not provide sufficient resolution to discern differences between the genders. Both genders were similar in the pattern of sugar content of nectar during floral development. A splitplot factorial design revealed significant differences both among individual plants and stages of floral phenology within each gender. The spectrophotometric technique and statistical analysis provided the needed resolution to discern differences between the genders that we relate to pollinator activity, levels of inbreeding depression, and the maintenance of gynodioecy in this taxon.     

Gender polymorphism in flowers of Silene vulgaris (Moench) Garcke (Caryophyllaceae)

Silene vulgaris occurs in Israel as a stolonifcrous tetraploid which forms mostly sexually polymorphic populations. Fully hermaphrodite and fully male-sterile plants are linked by a range of intermediate forms which are gynomonoecious and bear hermaphrodite, male-sterile, and partially male-sterile flowers. Male-sterile flowers differ from hermaphrodite ones by having a narrower calyx, a shorter corolla, a thicker style, and a considerably larger stigmatic area with longer papillae which are more markedly bulbous basally. In individual anthers of hermaphrodite flowers, diameters of stained pollen grains showed a continuous variation from 36 to 80 μm with a modal value of 56. About 30% of pollen was found to be non-stainable. Reduction in male fertility occurs at different levels, from small or inviable pollen grains through abortion of single anthers, abortion of entire androecia, and through different degrees of gynomonoecy to totally male-sterile individuals. The proportion of stainable pollen to ovules in hermaphrodite flowers alone was found to be less than 100. From the data presented, less than a third of all ovules produced in the different kinds of flower develop into seeds. This may reflect an inadequacy of pollen, which the local population of S. vulgaris can tolerate because of its stoloniferous habit.     

国产驴蹄草的细胞地理学研究（英文）

为探讨国产毛茛科(Ranunculaceae)驴蹄草属(Caltha)两种植物的演化,该文利用传统染色体压片技术和流式细胞术,并结合前人染色体研究结果,对我国驴蹄草23个居群和花葶驴蹄草10个居群进行了细胞学研究。结果表明:驴蹄草是由四倍体(2n=4x=32)、六倍体(2n=6x=48)和八倍体(2n=8x=64)构成的多倍体复合群,花葶驴蹄草具有四倍体(2n=4x=32)和八倍体(2n=8x=64)两种倍性水平。驴蹄草和花葶驴蹄草均是四倍体较为常见,目前尚未见有二倍体报道。由于驴蹄草和花葶驴蹄草大部分居群采自中国青藏高原地区,可能在冰期时存在古二倍体,其适应性较弱,逐渐被其他的倍性取代,这是由于不同细胞型对环境适应性的结果。驴蹄草可能存在两条进化路线:一条是从甘肃到达云南;另一条是从西藏到达云南。前期分子系统学研究显示花葶驴蹄草与驴蹄草的亲缘关系较近,该研究结果中花葶驴蹄草染色体比驴蹄草要小,花葶驴蹄草可能比驴蹄草相对进化。目前花葶驴蹄草只有10个居群,还需进一步增加居群量来解析其演化路线。     

Structure of Silenan, a Pectic Polysaccharide from Campion Silene vulgaris (Moench) Garcke

A pectic polysaccharide named silenan, [alpha]D20 +148.6 degrees (c 0.1; H2O), was isolated earlier from the aerial part of campion, Silene vulgaris (Moench) Garcke. Silenan has been shown to contain homogalacturonan segments as "smooth regions" and rhamnogalacturonan fragments as "hairy regions". The present study reveals a generalization of structural features of silenan. Silenan was subjected to enzymic digestion with pectinase, to Smith degradation, and to lithium-degradation to determine the conforming poly- and oligosaccharide fragments of "hairy regions" of silenan. The NMR-spectral data and mass-spectrometry confirmed that the core of the ramified region of silenan consisted of residues of alpha-rhamnopyranose 2-O-glycosylated with the residues of alpha-1,4-D-galactopyranosyl uronic acid. The part of the alpha-rhamnopyranose residues of the backbone are branched at O-4. On the basis of the data, the hairy regions of silenan proved to contain mainly linear chains of beta-1,3-, beta-1,4-, and beta-1,6-galactopyranan and alpha-1,5-arabinofuranan. The side chains of the ramified region were shown to have branching points represented 2,3-, 3,6-, 4,6-di-O-substituted beta-galactopyranose residues.     

Isolation and structural study of polysaccharides from campion Silene vulgaris

Silenan SV, a pectic polysaccharide, was isolated from the aerial part of Silene vulgaris (Moench) Garke (Oberna behen (L.) Ikonn.), widespread through the European North of Russia. The polysaccharide was found to contain residues of galacturonic acid (63%), arabinose, galactose, and rhamnose as the main constituents. The results of a partial acidic hydrolysis, pectinase digestion, and NMR studies of silenan SV indicated that its molecule contains a linear alpha-1,4-D-galacturonan backbone and ramified regions. The core of the ramified regions is composed of residues of alpha-1,4-D-galacturonic acid along with 2-substituted alpha-rhamnopyranose residues. The NMR data showed that the silenan SV side chains are composed of the blocks built from the terminal alpha-1,5-linked arabinofuranose and beta-1,4-linked galactopyranose residues; these most likely are the side chains of rhamnogalacturonan, characteristic of other pectic polysaccharides. The nonreducing ends of these side chains contain alpha-arabinofuranose residues.     

Phytochelatins in Cadmium-Sensitive and Cadmium-Tolerant Silene vulgaris (Chain Length Distribution and Sulfide Incorporation)

In response to a range of Cd concentrations, the root tips of Cd-tolerant plants of Silene vulgaris exhibit a lower rate of PC production accompanied by a lower rate of longer chain PC synthesis than those of Cd-sensitive plants. At the same Cd exposure level, stable PC-Cd complexes are more rapidly formed in the roots of Cd-sensitive plants than in those of tolerant plants. At an equal PC concentration in the roots, the PC composition and the amount of sulfide incorporated per unit of PC-thiol is the same in both populations. Although these compounds might play some role in mechanisms that contribute to Cd detoxification, the ability to produce these compounds in greater amounts is not, itself, the mechanism that produces increased Cd tolerance in tolerant S. vulgaris plants.     

国产驴蹄草的细胞地理学研究

为探讨国产毛茛科(Ranunculaceae)驴蹄草属(Caltha)两种植物的演化,该文利用传统染色体压片技术和流式细胞术,并结合前人染色体研究结果,对我国驴蹄草23个居群和花葶驴蹄草10个居群进行了细胞学研究。结果表明:驴蹄草是由四倍体(2n=4x=32)、六倍体(2n=6x=48)和八倍体(2n=8x=64)构成的多倍体复合群,花葶驴蹄草具有四倍体(2n=4x=32)和八倍体(2n=8x=64)两种倍性水平。驴蹄草和花葶驴蹄草均是四倍体较为常见,目前尚未见有二倍体报道。由于驴蹄草和花葶驴蹄草大部分居群采自中国青藏高原地区,可能在冰期时存在古二倍体,其适应性较弱,逐渐被其他的倍性取代,这是由于不同细胞型对环境适应性的结果。驴蹄草可能存在两条进化路线:一条是从甘肃到达云南;另一条是从西藏到达云南。前期分子系统学研究显示花葶驴蹄草与驴蹄草的亲缘关系较近,该研究结果中花葶驴蹄草染色体比驴蹄草要小,花葶驴蹄草可能比驴蹄草相对进化。目前花葶驴蹄草只有10个居群,还需进一步增加居群量来解析其演化路线。     

Structural studies of arabinogalactan and pectin from Silene vulgaris (M.) G. callus

Arabinogalactan and pectin (named silenan) were isolated from Silene vulgaris (M.) G. callus. Fractionation by ion-exchange chromatography on DEAE-cellulose and digestion with pectinase demonstrated that silenan from S. vulgaris callus (80% of D-galacturonic acid) and silenan from the aerial part of the campion S. vulgaris are similar: both pectins contain a high quantity of homogalacturonan segments. The NMR spectral data and mass spectrometry of the purified polysaccharide and its fragment obtained by Smith degradation confirmed that the core of the arabinogalactan consisted of the different segments of β-1,3-D-galactopyranan. Some of the β-galactopyranose residues of the backbone are branched at O-6. The side chains of the arabinogalactan were shown to contain residues of terminal and 3-O-substituted β-galactopyranose, terminal α-arabinofuranose and α-rhamnopyranose, and 2-O-substituted α-rhamnopyranose. The α-rhamnopyranose residues in the sugar chain appeared to be 2-O-glycosylated by the β-1,4-D-galactopyranosyl uronic acid residues. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 6, pp. 798–807.     

Cytogeography of Cenchrus ciliaris (Poaceae) in Tunisia

Belonging to the genus Cenchrus with 16–22 species, Cenchrus ciliaris L. (syn. Pennisetum ciliare (L.) Link, buffelgrass) is a perennial, common in warmer regions of both hemispheres, growing as a C4 grass in a wide range of habitats. In the present study we determined chromosome number and nuclear DNA content (2C DNA) for 28 natural populations collected from northern to southern Tunisia. Three ploidy levels were found: one tetraploid population (2n?=?4x?=?36), three pentaploid (2n?=?5x?=?45), and 24 hexaploid populations (2n?=?6x?=?54). The hexaploid chromosome number has already been reported for Tunisian populations of C. ciliaris but tetraploid and pentaploid (2n?=?45) are new for this area. The tetraploid population was found in the semi-arid north; pentaploids were mostly on the northern side of the arid region, while the hexaploids were located mainly in the arid southern Tunisian and Saharan region. 2C DNA values, assessed using flow cytometry, correlated with chromosome counts. Nuclear DNA content ranged from 2C?=?3.03 to 4.61 pg, revealing three ploidy levels corresponding to 4x, 5x, 6x, and mean 2C DNA amounts were of 3.03, 3.7 and 4.48 pg, respectively. Each cytotype produced viable pollen. Flow cytometric seed screening neither proved nor disproved apomixis. The most frequent hexaploid populations seem best adapted to arid conditions in southern Tunisia. The monoploid value, 1Cx, was constant. The existence of pentaploid cytotype suggests hybridization ability between tetraploids and hexaploids. It appears that polyploidization is the major evolutionary mechanism in the speciation of C. ciliaris.     

Flower herbivory and seed predation in Silene vulgaris (Caryophyllaceae): effects of pollination and phenology

Pollination and seed predation were studied in Silene vulgaris populations during two seasons, one with much lower pollinator abundance than the other. Among the pollinators, noctuid moths of the genus Hadena also acted as seed predators. Nectar-foraging female moths oviposited in flowers, and their larvae consumed flowers and seed capsules.
Despite a lower percentage of pollinated flowers in the year of low pollinator abundance, similar numbers of flowers set fruit in both years, because fewer flower buds and flowers were eaten by Hadena larvae during the year of low pollinator visitation. The number of seed capsules preyed upon was also lower in the year with low pollinator abundance, resulting in a higher seed set. The positive correlation between the percentage of pollinated flowers and the percentage of seed capsules destroyed was also observed when comparing flowers opening in different parts of the season.
Early flowering plant individuals had the same pollination success but suffered higher seed predation than late flowering ones. Selection for maximized pollination success through synchronous flowering, is probably the main reason for the compressed flowering period in 5. vulgaris , but the high level of predation early in the season may further increase the reproductive success of synchronous flowering individuals.     

Nonneutral evolution of organelle genes in Silene vulgaris

Knowledge of mitochondrial gene evolution in angiosperms has taken a dramatic shift within the past decade, from universal slow rates of nucleotide change to a growing realization of high variation in rates among lineages. Additionally, evidence of paternal inheritance of plant mitochondria and recombination among mitochondrial genomes within heteroplasmic individuals has led to speculation about the potential for independent evolution of organellar genes. We report intraspecific mitochondrial and chloroplast sequence variation in a cosmopolitan sample of 42 Silene vulgaris individuals. There was remarkably high variation in two mitochondrial genes (atp1, atp9) and additional variation within a third gene (cob). Tests for patterns of nonneutral evolution were significant for atp1 and atp9, indicative of the maintenance of balanced polymorphisms. Two chloroplast genes (matK, ndhF) possessed less, but still high, variation and no divergence from neutral expectations. Phylogenetic patterns of organelle genes in both the chloroplast and mitochondria were incongruent, indicating the potential for independent evolutionary trajectories. Evidence indicated reassociation among cytoplasmic genomes and recombination between mitochondrial genes and within atp1, implying transient heteroplasmy in ancestral lineages. Although the mechanisms for long-term maintenance of mitochondrial polymorphism are currently unknown, frequency-dependent selection on linked cytoplasmic male sterility genes is a potential candidate.     

Inbreeding effects on progeny sex ratio and gender variation in the gynodioecious Silene vulgaris (Caryophyllaceae)

In gynodioecious species, sex expression is generally determined through cytoplasmic male sterility genes interacting with nuclear restorers of the male function. With dominant restorers, there may be an excess of females in the progeny of self-fertilized compared with cross-fertilized hermaphrodites. Moreover, the effect of inbreeding on late stages of the life cycle remains poorly explored. Here, we used hermaphrodites of the gynodioecious Silene vulgaris originating from three populations located in different valleys in the Alps to investigate the effects of two generations of self- and cross-fertilization on sex ratio and gender variation. We detected an increase in females in the progeny of selfed compared with outcrossed hermaphrodites and inbreeding depression for female and male fertility. Male fertility correlated positively with sex ratio differences between outbred and inbred progeny, suggesting that dominant restorers are likely to influence male fertility qualitatively and quantitatively in S. vulgaris. We argue that the excess of females in the progeny of selfed compared with outcrossed hermaphrodites and inbreeding depression for gamete production may contribute to the maintenance of females in gynodioecious populations of S. vulgaris because purging of the genetic load is less likely to occur.     

Inheritance of chloroplast DNA is not strictly maternal in Silene vulgaris (Caryophyllaceae): evidence from experimental crosses and natural populations

Chloroplast DNA (cpDNA) is maternally inherited in the majority, but not all, of angiosperm species. The mode of inheritance of cpDNA is a critical determinant of its molecular evolution and of its population genetic structure. Here, we present the results of investigations of the inheritance of cpDNA in Silene vulgaris, a plant used in a variety of studies in which cpDNA is an important component. PCR/RFLP markers were used to compare mother and offspring cpDNA genotypes sampled from two natural populations, and mother, father, and offspring genotypes obtained from controlled greenhouse crosses. Ten of 215 offspring cpDNA genotypes studied in the controlled crosses and three of 156 offspring from natural populations did not match that of the mother, demonstrating rare nonmaternal inheritance. That the chloroplast genome is occasionally transmitted through pollen is discussed in the context of using S. vulgaris cpDNA as a marker in studies of seed dispersal and when considering the joint evolution of the chloroplast and mitochondrial genomes.     

Isolation and characterization of highly polymorphic microsatellite loci in the bladder campion,Silene vulgaris (Caryophyllaceae)

This study reports the isolation and characterization of seven highly polymorphic microsatellite loci in Silene vulgaris (Caryophyllaceae). The loci were isolated from two libraries constructed from genomic DNA enriched for CA and GA repeats. These markers yielded nine to 40 alleles per locus (mean 22.1) in a survey of 45 individuals from a single population located in the western Swiss Alps. Average observed heterozygosity ranged from 16.2 to 77.4%. These microsatellite loci should be valuable tools for studying fine‐scale genetic structure.     

Density-dependent egg dispersion in flowers of Silene vulgaris by the seed predator Hadena confusa (Noctuidae)

Abstract.

• 1 Hadena moths drink nectar from, pollinate, and oviposit into the flowers of the genus Silene. In the gynodioecious Silene vulgaris (Moench) Garcke (Caryophyllaceae), eggs were laid by Hadena confusa (Hufn.) females both in male phase flowers, which could not be pollinated by the moth at the time of oviposition, and in female phase and female flowers that allowed pollination.
• 2 Flowers in which an egg had been laid had a lowered probability of receiving a second egg laid by another female during the same night.
• 3 The degree of flower discrimination by the moth with respect to the presence of eggs was positively correlated with the proportion of flowers containing eggs.
• 4 The oviposition behaviour of H.confusa is moulded by four factors: (1) a high probability of chosen male phase flowers later becoming pollinated by other moths, (2) the presence of conspecific eggs and risk for larval competition, (3) probability of presence of conspecific eggs also in neighbouring flowers, (4) capability of larvae to move to adjacent flowers.

     

Cytogeography of European perennial species of Cyanus (Asteraceae)

To reveal the general cytogeographical pattern of Cyanus section Protocyanus in Europe, DNA ploidy and/or chromosome numbers were newly examined for 160 populations by flow cytometry (450 plants) and/or chromosome counting (30 plants). Furthermore, previously published karyological data were revised (236 records). Our analyses confirmed chromosome counts of 2n = 22 for all newly investigated samples of the C. triumfetti group (the records for C. semidecurrens and C. ternopoliensis are new), C. diospolitanus and C. achtarovii; 2n = 44 for C. montanus and C. mollis; and 2n = 20 for C. lingulatus, C. napulifer, C. nissanus, C. orbelicus, C. thirkei, C. tuberosus and C. velenovskyi. The chromosome count of 2n = 20 is the first report for C. epirotus. The cytotype 2n = 40 was newly recorded for the Crimean endemic C. fuscomarginatus and Calabrian and Greek populations of C. graminifolius. The cytotypes 2n = 20 and 2n = 40 were confirmed for C. pindicola. For the first time triploidy (2n～3x～30) was found in C. nissanus, C. thirkei and in a newly discovered hybrid, C. epirotus × C. graminifolius. Two contrasting ecogeographical patterns emerged: cytotypes derived from the base chromosome number x = 11 (2n = 22, 44) are widespread in northern latitudes and ecologically diverse, whereas cytotypes with x = 10 (2n = 20, 30, 40) are confined to mountains in southern Europe. In general, tetraploids have smaller ranges than diploids. The new combinations Cyanus section Protocyanus (Dobrocz.) Ol?avská comb. nov. and Cyanus ternopoliensis (Dobrocz.) Ol?avská comb. nov. are provided. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 230–257.