Silene Latifolia Research Articles

Herbivory affects male and female reproductive success differently in dioecious Silene latifolia

AbstractIn dioecious plants, reproductive efforts of male and female plants can be differentially affected by herbivory due to sex‐specific allocation and re‐modulation of resources. Here, we investigate the effects of foliar herbivory by the polyphagous species Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) on male and female reproductive traits of Silene latifolia (Poir.) (Caryophyllaceae). We set up experimental populations of male and female control and Spodoptera‐infested plants and estimated flower morphology and phenology, and plant reproductive success. Herbivory did not affect floral traits involved in visual signalling to pollinators (flower size). Female reproductive success did not differ between Spodoptera‐infested and control plants in terms of seed set and seed germination. On the other hand, Spodoptera‐infested male plants produced fewer flowers than male control plants and maintained fewer flowers during flowering peaks. By experimental reduction in male flower number, we showed that male flower number is directly correlated with male reproductive success (pollen export to female flowers). This strongly suggests that male reproductive success is reduced after herbivory, whereas female reproductive success remains unaffected. The fact that females are more tolerant against herbivory is in accordance with sexual selection theory, which predicts that females, in contrast to males, are not selected for maximum investment in reproductive traits such as floral signalling, and should thus be more flexible in the allocation of resources.

Differences in style length confer prezygotic isolation between two dioecious species of Silene in sympatry.

One fundamental signature of reinforcement is elevated prezygotic reproductive isolation between related species in sympatry relative to allopatry. However, this alone is inadequate evidence for reinforcement, as traits conferring reproductive isolation can occur as a by-product of other forces. We conducted crosses between Silene latifolia and S. diclinis, two closely related dioecious flowering plant species. Crosses with S. latifolia mothers from sympatry exhibited lower seed set than mothers from five allopatric populations when S. diclinis was the father. However, two other allopatric populations also exhibited low seed set. A significant interaction between style length and sire species revealed that seed set declined as style length increased when interspecific, but not intraspecific, fathers where used. Moreover, by varying the distance pollen tubes had to traverse, we found interspecific pollen placement close to the ovary resulted in seed set in both long- and short-styled S. latifolia mothers. Our results reveal that the long styles of S. latifolia in sympatry with S. diclinis contribute to the prevention of hybrid formation. We argue that forces other than reinforcing selection are likely to be responsible for the differences in style length seen in sympatry.

Herbivory Increases Fruit Set in Silene latifolia: A Consequence of Induced Pollinator-Attracting Floral Volatiles?

Although the effect of herbivory on plant reproduction has been investigated in some detail, little is known about how herbivores affect floral signalling. Here, we investigated the effect of foliar herbivory by the African Cotton Leafworm (Spodoptera littoralis) on floral signalling and fruit set in the White Campion (Silene latifolia). We found no effects of herbivory on floral traits involved in visual signalling (flower number, corolla diameter, calyx length, petal length) or in amount of nectar produced. However, Spodoptera-infested plants emitted higher amounts of the two floral volatiles, (Z)-3-hexenyl acetate and β-ocimene, than control plants. Open pollinated, infested plants also were found to produce more fruits than control plants, but only with nocturnal pollinators. Experimental addition of the two induced floral volatiles to non-infested Silene flowers also led to the production of more fruits with nocturnal pollination. This suggests that higher fruit production in herbivore-infested plants was caused by increased nocturnal pollinator attraction, mediated by the induced floral emission of these two volatiles. Our results show that the effects of herbivory on plant reproductive success are not necessarily detrimental, as plants can compensate herbivory with increased investment in pollinator attraction.

Sex and parasites: genomic and transcriptomic analysis of Microbotryum lychnidis-dioicae, the biotrophic and plant-castrating anther smut fungus.

BackgroundThe genus Microbotryum includes plant pathogenic fungi afflicting a wide variety of hosts with anther smut disease. Microbotryum lychnidis-dioicae infects Silene latifolia and replaces host pollen with fungal spores, exhibiting biotrophy and necrosis associated with altering plant development.ResultsWe determined the haploid genome sequence for M. lychnidis-dioicae and analyzed whole transcriptome data from plant infections and other stages of the fungal lifecycle, revealing the inventory and expression level of genes that facilitate pathogenic growth. Compared to related fungi, an expanded number of major facilitator superfamily transporters and secretory lipases were detected; lipase gene expression was found to be altered by exposure to lipid compounds, which signaled a switch to dikaryotic, pathogenic growth. In addition, while enzymes to digest cellulose, xylan, xyloglucan, and highly substituted forms of pectin were absent, along with depletion of peroxidases and superoxide dismutases that protect the fungus from oxidative stress, the repertoire of glycosyltransferases and of enzymes that could manipulate host development has expanded. A total of 14 % of the genome was categorized as repetitive sequences. Transposable elements have accumulated in mating-type chromosomal regions and were also associated across the genome with gene clusters of small secreted proteins, which may mediate host interactions.ConclusionsThe unique absence of enzyme classes for plant cell wall degradation and maintenance of enzymes that break down components of pollen tubes and flowers provides a striking example of biotrophic host adaptation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1660-8) contains supplementary material, which is available to authorized users.

Genomic Resources Notes accepted 1 February 2015 - 31 March 2015.

This article documents the public availability of (i) raw transcriptome sequence data, assembled contigs and BLAST hits of the Antarctic plant Colobanthus quitensis grown in two different climatic conditions, (ii) the draft genome sequence data (raw reads, assembled contigs and unassembled reads) and RAD-tag read data of the marbled flounder Pseudopleuronectes yokohamae, (iii) transcriptome resources from four white campion (Silene latifolia) individuals from two morphologically divergent populations and (iv) nuclear DNA markers from 454 sequencing of reduced representation libraries (RRL) based on amplified fragment length polymorphism (AFLP) PCR products of four species of ants in the genus Tetramorium.

Chaos of Rearrangements in the Mating-Type Chromosomes of the Anther-Smut Fungus Microbotryum lychnidis-dioicae.

Sex chromosomes in plants and animals and fungal mating-type chromosomes often show exceptional genome features, with extensive suppression of homologous recombination and cytological differentiation between members of the diploid chromosome pair. Despite strong interest in the genetics of these chromosomes, their large regions of suppressed recombination often are enriched in transposable elements and therefore can be challenging to assemble. Here we show that the latest improvements of the PacBio sequencing yield assembly of the whole genome of the anther-smut fungus, Microbotryum lychnidis-dioicae (the pathogenic fungus causing anther-smut disease of Silene latifolia), into finished chromosomes or chromosome arms, even for the repeat-rich mating-type chromosomes and centromeres. Suppressed recombination of the mating-type chromosomes is revealed to span nearly 90% of their lengths, with extreme levels of rearrangements, transposable element accumulation, and differentiation between the two mating types. We observed no correlation between allelic divergence and physical position in the nonrecombining regions of the mating-type chromosomes. This may result from gene conversion or from rearrangements of ancient evolutionary strata, i.e., successive steps of suppressed recombination. Centromeres were found to be composed mainly of copia-like transposable elements and to possess specific minisatellite repeats identical between the different chromosomes. We also identified subtelomeric motifs. In addition, extensive signs of degeneration were detected in the nonrecombining regions in the form of transposable element accumulation and of hundreds of gene losses on each mating-type chromosome. Furthermore, our study highlights the potential of the latest breakthrough PacBio chemistry to resolve complex genome architectures.

Host Flower Infection of Silene latifolia by Microbotryum violaceum

Certain fungi can infect host plants and thereby cause sterility of the host. One such fungal parasite, Microbotryum violaceum (commonly known as anther smut), has host specificity to plants of the family Caryophyllaceae. Anther smut takes over the host reproductive system by inhibiting sex-organ development in flowers, and the plant produces fungal spores in place of its normal reproductive structures. Spores can then be spread to nearby hosts through wind and insect pollinators. This experiment focuses on Silene latifolia plant populations growing near Zagreb, Croatia. Our research tests for phenotypic differences between infected and healthy flowers. To do this, we measured the size of healthy and infected flowers of both sexes. Additionally, we observed the proportion of infected flowers over time on individuals to uncover temporal trends of the smut infection. We found that all flower parts, regardless of plant sex, are significantly smaller in smut-infected flowers. After observing proportions of infected flowers, we found that the ratio of infected to healthy flowers increased over time. Our findings suggest that smut infection of S. latifolia causes changes in plant energy allocation. We propose that the smaller flower size could be the result of increased energy needed for M. violaceum spore production. This hypothesis could be tested with additional research. The increasing proportion of smutty flowers on an infected individual over time is likely caused by the spread of the infection throughout the plant.

Genome size estimates for six rust (Pucciniales) species

Rust fungi (Basidiomycota, Pucciniales), one of the largest groups of phytopathogenic organisms, are characterised by host specialisation, biotrophy, complex life cycles and enlarged genomes. In this work we have used flow cytometry to determine the genome size of six rust species, Melampsora pulcherrima, Puccinia behenis, P. cichorii, P. pimpinellae, P. vincae and Uromyces dianthi, the causal agents of rust on Mercurialis annua, Silene latifolia, Cichorium intybus, Pimpinella villosa, Vinca major and Dianthus caryophyllus, respectively. With results ranging between 182.1 and 566.4 Mbp/1C, this study has contributed to the knowledge of genome sizes in the order Pucciniales, reinforcing this group as the one with the largest average genome size among fungi, with 335.6 Mbp/1C. By comparing genome sizes and their variability across the fungal kingdom, this study has contributed for understanding the patterns of genome size distribution along the fungal phylogeny, suggesting links between biological specificities and genome sizes. In particular, genome sizes of rust fungi vary greatly within genera, but also differ sharply from other non- Pucciniales orders in the Pucciniomycotina, suggesting that genome size variation may be an active element shaping the evolution of rust fungi.

Brachycaudus species on herbaceous plants along highways in Hungary

Survey of aphids on dicotyledonous herbaceous plants along the Hungarian highways on 33 sampling points revealed the presence of four holocyclic Brachycaudus species. The monoecious B. lychnidis L. 1758 was the most frequently collected species. It colonised the perennial Silene alba (Mill.) E. H. L. Krause 1893 on the youngest highway section around Budapest (5 locations). The frequency of this species is due to frequent occurrence of its host plant on this section compared to other host species. New record for the Hungarian fauna is the occurrence of monoecious B. setosus Hille Ris Lambers 1948 on the biennial or perennial Tragopogon orientalis L. 1753 on two locations on the southern part of the country. The heteroecious B. cardui L. 1758 was found on biennial or perennial Senecio jacobaea L. 1753 in one location on north-western part of Hungary. On the north-eastern part of the country the perennial Symphytum officinale subsp. bohemicum (F. W. Schmidt) Čelak 1891 occurred on a damp area. The monoecious B. mordvilkoi Hille Ris Lambers 1931 colonised this Boraginaceae species.

Gene loss from a plant sex chromosome system

Sex chromosomes have evolved independently in numerous animal and plant lineages. After recombination becomes suppressed between two homologous sex chromosomes, genes on the non-recombining Y chromosomes (and W chromosomes in ZW systems) undergo genetic degeneration, losing functions retained by their X- or Z-linked homologs, changing their expression, and becoming lost [1, 2]. Adaptive changes may also occur, both on the non-recombining Y chromosome, to shut down expression of maladapted genes [3], and on the X chromosome (or the Z in ZW systems), which may evolve dosage compensation to increase low expression or compensate for poor protein function in the heterogametic sex [2, 4, 5]. Although empirical approaches to studying genetic degeneration have been developed for model species [3, 6], the onset and dynamics of these changes are still poorly understood, particularly in de novo evolving sex chromosomes. Sex chromosomes of some plants evolved much more recently than those of mammals, birds, and Drosophila [7-9], making them suitable for studying the early stages of genetic degeneration in de novo evolving sex chromosomes. In plants, haploid selection should oppose gene loss from Y chromosomes, but recent work on sex chromosomes of two plant species has estimated that Y-linked transcripts are lacking for 10%-30% of X-linked genes [10-12]. Here, we provide evidence that, in Silene latifolia, this largely involved losses of Y-linked genes, and not suppressed expression of Y-linked alleles, or gene additions to the X chromosome. Our results also suggest that chromosome-wide dosage compensation does not occur in this plant.

The effects of agrochemicals on Lepidoptera, with a focus on moths, and their pollination service in field margin habitats

In agricultural landscapes, field margins are potential habitats for moths and butterflies (Lepidoptera). However, because of their proximity to agricultural sites, field margins can be affected by inputs of pesticides and fertilizers. In the present study, we assessed the use of field margins by caterpillars as habitat. Furthermore, the effects of realistic field margin input rates of various agrochemicals on moths, especially on their caterpillar stages, were studied in field, semi-field, and laboratory experiments. Our monitoring results indicate that, although caterpillars were found in field margins, their mean abundance was 35–60% lower compared to meadows. In a field experiment, the insecticide treatment (pyrethroid, lambda-cyhalothrin) significantly reduced the number of caterpillars and only 15% of the sampled caterpillars occurred in the insecticide-treated plots. Furthermore, the insecticide affected the community composition of the caterpillars, whereas the fertilizer treatment slightly increased the caterpillar abundance. In laboratory experiments, Mamestra brassicae caterpillars were shown to be very sensitive when exposed to insecticide-treated leaves (rate that kills 50% of the test caterpillars (LR50) after 48h: 0.78% of the recommended field rate; this rate corresponds to the arable spray drift input in field margins at a distance of 3–4m from the crop), and the caterpillars also appeared to avoid feeding on the treated leaves. In addition, in a semi-field study, 40% fewer eggs of Hadena bicruris moths were found on Silene latifolia plants sprayed with the insecticide compared to control plants and the flowers of insecticide-treated plants were less likely to be pollinated by moths. Overall, these studies illustrate that moths use field margins as habitats and that they can be affected by realistic input rates of agrochemicals. As caterpillars are important prey organisms and adult moths can act as pollinators, inputs of agrochemicals in field margins should be reduced to maintain biodiversity in agricultural landscapes.

A hundred years of change in wild vegetable use in southern Herzegovina

Ethnopharmacological relevanceWild vegetable mixes used in southern Europe are interesting from the pharmacological point of view, as they contain many species which have considerable nutritional and medicinal value, but some are potentially toxic to humans. Although many ethnobotanical studies document the rich tradition of using wild vegetables at the turn of the 20th and 21st century in the Mediterranean region, there is a dearth of older historical studies which could help us to assess the extent of Traditional Knowledge loss. Material and methodsThe aim of this study was to document the use of wild foods in an area of southern Herzegovina (in Bosnia–Herzegovina) and to compare it with a list of 27 taxa of wild green vegetables used there, compiled in 1913 by Vejsil Ćurčić. We carried out 49 interviews in the same area to estimate the current use and knowledge of wild foods. ResultsEighty-two species of wild food and herbal tea plants were recorded in the study. This includes 44 species whose wild leaves are used as salads or cooked side dishes, 17 species with edible fruits and 24 species whose leaves, shoots or flowers are used for everyday herbal teas. On average, 14.2 species (median=16.5) were listed per interview, including 9.0 species of wild vegetables. Out of 27 plant names mentioned 100 years ago – five remain unidentified. Out of the 22 species or species groups, which were identified, 18 are still used as wild vegetables (including five species used very rarely and known by very few people or only by one person).Nowadays, the most commonly used wild greens are: Dioscorea communis, Sonchus spp., Allium spp., Papaver rhoeas, Rumex pulcher, Silene latifolia, and Taraxacum spp. ConclusionsAlthough we observed some changes in the names and uses of plants compared to the list from a hundred years ago, around three quarters of the taxa are still used to some extent nowadays.

The slow‐growth high‐mortality hypothesis: direct experimental support in a leafmining fly

1. Based on the slow‐growth high‐mortality (SGHM) hypothesis, which predicts that prolonged larval development increases mortality from their natural enemies, studies have often assumed that low quality of plants that slows larval development would function as a defence against insect herbivores. However, empirical support for the SGHM hypothesis has been limited, especially in natural and ecologically relevant contexts.2. In a leafminer Amauromyza flavifrons Meigen (Agromyzidae, Diptera), the SGHM hypothesis was tested along with four other hypotheses (e.g. prey size, mine appearance, density‐dependent parasitism, and plant quality hypotheses) to control for spurious associations between development time and parasitism that are primarily driven by other larval traits. Two host plant species, Saponaria officinalis and Silene latifolia, were grown under varying nitrogen levels, and leafminers developing on these plants were exposed to, or protected from, a natural assembly of parasitoids across the entire course of larval development.3. On both host plant species, leafminers that survived to an adult stage in the presence of parasitoids had a shorter development time than those in the absence of parasitoids, indicating that parasitoids disproportionately kill leafminers with longer larval development. The results provided concrete evidence for the SGHM hypothesis within the natural ecological context for these interacting species. Moreover, reduced plant quality was associated with higher larval mortality on Sa. officinalis only in the presence of parasitoids, suggesting that low quality could function as indirect plant resistance via SGHM under some tri‐trophic interactions.

The population biology of fungal invasions.

Fungal invasions are increasingly recognized as a significant component of global changes, threatening ecosystem health and damaging food production. Invasive fungi also provide excellent models to evaluate the generality of results based on other eukaryotes. We first consider here the reasons why fungal invasions have long been overlooked: they tend to be inconspicuous, and inappropriate methods have been used for species recognition. We then review the information available on the patterns and mechanisms of fungal invasions. We examine the biological features underlying invasion success of certain fungal species. We review population structure analyses, revealing native source populations and strengths of bottlenecks. We highlight the documented ecological and evolutionary changes in invaded regions, including adaptation to temperature, increased virulence, hybridization, shifts to clonality and association with novel hosts. We discuss how the huge census size of most fungi allows adaptation even in bottlenecked, clonal invaders. We also present new analyses of the invasion of the anther-smut pathogen on white campion in North America, as a case study illustrating how an accurate knowledge of species limits and phylogeography of fungal populations can be used to decipher the origin of invasions. This case study shows that successful invasions can occur even when life history traits are particularly unfavourable to long-distance dispersal and even with a strong bottleneck. We conclude that fungal invasions are valuable models to contribute to our view of biological invasions, in particular by providing insights into the traits as well as ecological and evolutionary processes allowing successful introductions.

<i>Silene latifolia</i> temporal patterns of volatile induction and suppression after floral interaction by the nursery pollinator, <i>Hadena bicruris</i> (Lepidoptera: Noctuidae)

After 24-hour Hadena bicruris floral interaction on Silene latifolia (Caryophyllaceae) with or without oviposition, we examined temporal volatile emission patterns for 3 days from plants with moth interaction and from neighboring plants only exposed to plant volatiles. Several lilac aldehydes and veratrole were progressively reduced after moth exposure without oviposition (by 30 to 40% after 24 hours and by 60 to 90% after 72 hours), but β -myrcene and β -pinene emissions increased by 200 to 300% only when exposure involved oviposition. Exposing S. latifolia to H. bicruris floral interaction without oviposition yielded no change in volatile organic compound (VOC) emission of neighboring S. latifolia; with oviposition, neighboring plants had 80 to126% increases in emission rates for β -myrcene and β -pinene. Progressive reduction of S. latifolia VOC emission rates might help plants to avoid nursery pollinator oviposition. In contrast, with H. bicruris oviposition on S. latifolia flowers some VOCs (common herbivore induced plant volatiles i. e. HIPVs) were induced. Whether oviposition occurred on S. latifolia strongly influenced neighboring plant VOC emission.

Flower development, pollen fertility and sex expression analyses of three sexual phenotypes of Coccinia grandis.

BackgroundCoccinia grandis is a dioecious species of Cucurbitaceae having heteromorphic sex chromosomes. The chromosome constitution of male and female plants is 22 + XY and 22 + XX respectively. Y chromosome of male sex is conspicuously large and plays a decisive role in determining maleness. Sex modification has been studied in hypogynous Silene latifolia (Caryophyllaceae) but there is no such report in epigynous Coccinia grandis. Moreover, the role of organ identity genes during sex expression in Coccinia has not been evaluated earlier. Investigations on sexual phenotypes of C. grandis including a rare gynomonoecious (GyM) form and AgNO3 mediated sex modification have added a new dimension to the understanding of sex expression in dioecious flowering plants.ResultsMorphometric analysis showed the presence of staminodes in pistillate flowers and histological study revealed the absence of carpel initials in male flowers. Though GyM plant had XX sex chromosomes, the development of stamens occurred in hermaphrodite flowers but the pollens were not fertile. Silver nitrate (AgNO3) application enhanced stamen growth in wild type female flowers like that of GyM plant but here also the pollens were sterile. Differential expression of CgPI could be involved in the development of different floral phenotypes.ConclusionsThe three principle factors, Gynoecium Suppression (SuF), Stamen Promoting Factor (SPF) and Male Fertility (mF) that control sex expression in dioecious C. grandis assumed to be located on Y chromosome, play a decisive role in determining maleness. However, the characteristic development of stamens in hermaphrodite flowers of GyM plant having XX sex chromosomes indicates that Y-linked SPF regulatory pathway is somehow bypassed. Our experimental findings together with all other previous chromosomal and molecular cytogenetical data strongly support the view that C. grandis could be used as a potential model system to study sex expression in dioecious flowering plant.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0325-0) contains supplementary material, which is available to authorized users.

Determinants of genetic structure in a nonequilibrium metapopulation of the plant Silene latifolia.

Population genetic differentiation will be influenced by the demographic history of populations, opportunities for migration among neighboring demes and founder effects associated with repeated extinction and recolonization. In natural populations, these factors are expected to interact with each other and their magnitudes will vary depending on the spatial distribution and age structure of local demes. Although each of these effects has been individually identified as important in structuring genetic variance, their relative magnitude is seldom estimated in nature. We conducted a population genetic analysis in a metapopulation of the angiosperm, Silene latifolia, from which we had more than 20 years of data on the spatial distribution, demographic history, and extinction and colonization of demes. We used hierarchical Bayesian methods to disentangle which features of the populations contributed to among population variation in allele frequencies, including the magnitude and direction of their effects. We show that population age, long-term size and degree of connectivity all combine to affect the distribution of genetic variance; small, recently-founded, isolated populations contributed most to increase F ST in the metapopulation. However, the effects of population size and population age are best understood as being modulated through the effects of connectivity to other extant populations, i.e. F ST diminishes as populations age, but at a rate that depends how isolated the population is. These spatial and temporal correlates of population structure give insight into how migration, founder effect and within-deme genetic drift have combined to enhance and restrict genetic divergence in a natural metapopulation.

Performance of a Hybrid Fungal Pathogen on Pure-Species and Hybrid Host Plants

Premise of research. Recent hybridization events in fungi have produced emerging pathogens characterized by novel host specificities, increased infectivity, and/or elevated severity. We investigated the potential for host shifts and increased infectivity following hybridization of fungal pathogens in the genus Microbotryum, which causes anther-smut disease on caryophyllaceous hosts. Hybrids of the closely related species Microbotryum lychnidis-dioicae (MvSl) and Microbotryum silenes-dioicae (MvSd) are viable and fertile. Although historical genetic exchange between MvSl and MvSd is rare, there is evidence of recent hybridization of these fungal species, as well as of their plant hosts, Silene latifolia and Silene dioica. Methodology. We examined the fitness of hybrid pathogens and hosts by using F1 hybrids of MvSl × MvSd to inoculate S. latifolia × S. dioica hybrids. Experimental inoculations of S. latifolia and hybrid hosts with pure-species and hybrid pathogens allowed assessment of the likelihood of hybrid emergence on a novel host (the hybrid plant) and of increased infectiousness of the hybrid pathogen on the pure-species host. Pivotal results. We found no evidence for pathogen hybrid inferiority, arguing against interspecific incompatibilities at small genetic distances. Instead, we found that hybrid pathogens are more infectious on pure-species hosts, while pure-species pathogens are more infectious on hybrid hosts, indicating an interaction of host and parasite genotypes. Conclusions. This finding argues against emergence of hybrid pathogens on a novel hybrid host. However, our study suggests that hybridization of pathogens and hosts in natural populations may lead to elevated disease prevalence overall, thus furthering the impact of anther-smut disease in these Silene species.

The X Chromosome Is Necessary for Somatic Development in the Dioecious Silene latifolia: Cytogenetic and Molecular Evidence and Sequencing of a Haploid Genome

Silene latifolia (or white campion) possesses a well-established sex determination system with a dominant Y chromosome in males (the mammalian type). The heteromorphic sex chromosomes X and Y in S. latifolia largely stopped recombination; thus, we can expect a gradual genetic degeneration of the Y chromosome. It is well proven that neither diploid nor polyploid S. latifolia sporophytes can survive without at least one X, so the only life stage possessing the Y as the sole sex chromosome is the male gametophyte (pollen tube), while the female gametophyte seems to be X-dependent. Previous studies on anther-derived plants of this species showed that the obtained plants (largely haploid or dihaploid) were phenotypically and cytologically female. In this paper, we provide molecular evidence for the inviability of plants lacking the X chromosome. Using sex-specific PCR primers, we show that all plantlets and plants derived from anther cultures are female. In studying anther-derived diploid females by sequencing of X-linked markers, we demonstrate that these plants are really homozygous dihaploids. A haploid regenerant plant was sequenced (8× genome coverage) using Illumina technology. Genome data are disposable in the EMBL database as a standard for full genome and X chromosome assembly in this model species. Homozygous dihaploids were back-crossed with males to yield a progeny useful for the study of the evolution of the Y chromosome.

Do flower color and floral scent of silene species affect host preference of Hadena bicruris, a seed-eating pollinator, under field conditions?

Specialization in plant–insect interactions is an important driver of evolutionary divergence; yet, plant traits mediating such interactions are poorly understood. In this study, we investigated how flower color and floral scent are related to seed predation by a seed-eating pollinator. We used field-transplanted recombinant F2 hybrids between Silene latifolia and S. dioica that are the preferred and alternative hosts of the moth Hadena bicruris and crosses within these species for comparison. We scored seed predation and flower color and analyzed floral scent. Pinker S. dioica-like flowers and emission of α-pinene decreased the odds of seed predation while emission of benzyl acetate and 6-methyl-5-hepten-2-one increased the odds of seed predation. Emission of these compounds did not differ significantly between the two Silene species. Our results suggest that flower color plays an important role in the specific interaction of H. bicruris with its preferred host S. latifolia. The compounds α-pinene, benzyl acetate and 6-methyl-5-hepten-2-one could represent non-specific deterrents and attractants to ovipositing moths. Alternatively, emission of these compounds could be related to herbivory or pathogen attack and act as a signal for host quality. This would weaken the predictability of the plant's costs and benefits of the interaction and act to maintain an imperfect degree of specialization.