Abstracts

Abstracts

13 October 2025

The evolution of calyx shape in Silene

Farzaneh Jafari1,2, Ladislav Hodač3

The shape of the calyx in the species-rich genus Silene, with about 870 species, is highly diversified. The calyx shape in the genus varies from obovate (S. davidii) to narrowly oblanceolate (S. elymaitica). Apart from traits such as the degree of inflation, the type of indumentum, and the venation pattern, the shape of the calyx is considered the most important diagnostic morphological feature in Silene. For classifying natural groups, i.e., sections, morphological features are assumed to reflect the history of morphological diversification. Our aim is to investigate whether the calyx shape in Silene exhibits a phylogenetic signal. We also investigated how the two main subgenera differ in their geographic distribution.

Landmark geometric morphometrics (GM) was employed to analyze the calyx shapes of 432 herbarium specimens representing 160 species from three subgenera and 30 sections. Our sampling included primarily species of the subgenera Silene and Behenantha distributed across the Northern Hemisphere, from temperate to Arctic regions. Using calyx shape information, the geographical locations of herbarium specimens, and phylogenetic information on the studied species, we conducted a phylomorphological analysis. To place the distributions of the subgenera Silene and Behenantha into a broader biogeographic context, we additionally analyzed over 20,000 occurrence records retrieved from GBIF.

The phylomorphological analysis revealed a significant phylogenetic signal in calyx shape. The obelliptic shape as the ancestral form shifts to narrower calyx shapes in the subgenus Silene (S. elymaitica), but in contrast it shifts to wider calyx shapes in the subgenus Behenantha (S. davidii). The association between altitude and calyx shape was significant within subg. Behenantha, but not within subg. Silene. The geographical comparison based on GBIF occurrence data revealed that the distribution area of subgenus Behenantha is significantly shifted toward higher latitudes and more eastern regions compared to subgenus Silene. Although the calyx shape reflects phylogenetic history, environmental factors also play an important role in shaping calyx morphology in the genus Silene.

A phylogenomic study of southern African members of Silene section Elisanthe (Caryophyllaceae)

Ntwai A. Moiloaa,b,h, Paola de Lima Ferreirab,c, Patrik Cangrena,b, John Manninge,f, Félix Forestg, Christine D. Bacona,b, Hugo J. de Boerd, Bengt Oxelmana,b

Silene section Elisanthe (Caryophyllaceae) is represented in southern Africa by perennial herbaceous endemic species. The most recent taxonomic treatment recognised five taxa viz. S. ornata, S. rigens, S. saldanhensis, S. undulata subsp. undulata and S. undulata subsp. polyantha. Three (S. ornata, S. rigens, S. saldanhensis) of the five taxa are endemic to the Core Cape Subregion of South Africa, while S. undulata subsp. polyantha is restricted to the KwaZulu Natal–Swaziland region and S. undulata subsp. undulata is widely distributed across southern Africa. Although the phylogenetic position of the southern African section Elisanthe has recently been clarified, the species relationships within the section remain unclear. This study aims to reconstruct the phylogenetic relationships of southern African members of section Elisanthe focussing on inferring a species-level phylogeny and testing the current taxonomic classification. We collected tissue from multiple specimens of the currently recognised taxa across southern Africa. We generated target sequence capture data using custom taxon-specific baits designed to target 48 low copy nuclear genes together with ITS and rps16. We employed a Bayesian species-tree inference method to estimate the phylogenetic relationships using STACEY and ASTRAL-III under the multispecies coalescent model framework. Our results show that the Saldanha Bay endemic species S. ornata and S. saldanhensis are monophyletic sister species. This clade is subsequently sister to the monophyletic West Coast endemic S. rigens. The STACEY analysis recovered Silene undulata as monophyletic, and in most respects topologically in agreement with the unrooted ASTRAL-III tree. Our results show that the relationships in Silene section Elisanthe are strongly correlated to geographical distribution. Our analyses do not support the intraspecific classification of the widespread S. undulata but rather highlight that the taxon is diverse, requires further investigation to better understand the intraspecific patterns observed in our results as well as other recent taxonomic studies.

Examining possible roles in the interaction of Microbotryum and Silene latifolia of effector proteins MVLG_01732 and MVLG_04107

Derica G. Tavares, Joseph Ham, Kelechi Onyiri, Nassara Shamsudeen, Michael H. Perlin

Microbotryum fungi employ a series of effector proteins to block the plant immune response and manipulate the host during infection, often exhibiting highly specific host species preference. Here, we studied two small secreted proteins (SSPs), MVLG_01732 and MVLG_04107, which may be important for the parasitic interaction. The aim of this work was to evaluate the infection of Silene latifolia with Microbotryum lychnidis-dioicae (MVLG) overexpressing its native gene MVLG_01732 and with a transgenic Microbotryum Silenes-dioicae (MvSd), a closely related species, expressing MVLG_04107. Transgenic compatible mating strains were used to infect S. latifolia, and the number of buds, branches, teliospores, and the relative gene expression of MVLG_01732 or MVLG_04107 from small and large buds were evaluated. Overexpression of MVLG_01732 appears to increase the percentage of buds (12% to 21.3%) and branches (2.5% to 4.9%) per plant, and the number of teliospores (2.7 x 106/mL to 4.3 x 106/mL) compared to wild-type MVLG infection. The relative expression of MVLG_01732 was higher in the transgenic line than in the wild-type MVLG and appears to be more important at the early budding stage. MvSd bearing MVLG_04107 was able to infect a higher number of S. latifolia (41.8%) compared to wild-type MvSd (29.5%), and a higher number of buds, branches, and teliospores were observed. The relative expression of MVLG_04107 was confirmed in buds of plants infected with transgenic MvSd and appears to be most important at the early bud stage. Our previous study proposed that MVLG_01732 may normally delay anther development, giving the fungus the opportunity to replace pollen with its teliospores. Here, we showed an increase in the number of buds and teliospores in plants infected with MVLG overexpressing MVLG_01732; importantly, the effector MVLG_04107 may increase the chances of infection by a pathogen like MvSd, of its non-preferred host, S. latifolia.

The evolutionary history of the arctic-alpine Silene acaulis species complex

Oliver Reutimann1, Gwyneth Halstead-Nussloch1, Andreas Tribsch2, Pablo Tejero Ibarra3, Niklaus Zemp4, Alex Widmer1, Martin C. Fischer1

Populations of the arctic-alpine Silene acaulis species complex were strongly influenced by glacial cycles and thus by the availability of cold habitats to which they are adapted. Understanding the evolutionary history of arctic-alpine species can provide insights into how they responded to past climatic shifts, which may help us predict their responses to ongoing climate change. In this study, we explored the glacial and evolutionary dynamics of the S. acaulis species complex. We produced the first high-quality reference genome for S. acaulis and analyzed ddRAD sequencing data from 955 individuals across 132 populations distributed throughout its Holarctic distribution range. We identified five evolutionary lineages, whose phylogeographic patterns were examined in relation to existing subspecies classifications, glacial refugia, and historical migration routes. Molecular dating indicated that lineage divergence largely aligned with repeated glacial cooling episodes over the past two million years, primarily driven by isolation within refugial areas. Periods of secondary contact, either within refugia or during interglacial expansions, facilitated introgression, further influencing the genetic properties of the species complex. In the European Alps, adaptive divergence among co-occurring lineages underscores the importance of niche specialization, with evidence pointing to ecotype differentiation in response to environmental factors, especially isothermality and soil preferences. Overall, the evolutionary trajectory of the S. acaulis complex reflects a history shaped by Late Pleistocene glacial cycles, which promoted lineage diversification, secondary contact, and the emergence of ecotypes. This research highlights the critical role of glacial dynamics in structuring genetic diversity within and among arctic-alpine plant species and enhances our understanding of their historical responses to climatic changes.

Thallium-induced metabolic adjustments in the facultative hyperaccumulator Silene latifolia

Marco Dainelli1, Gaia Regini1, Stéphanie Boutet2, Massimiliano Corso2, Ilaria Colzi1, Nadia Bazihizina1, Antony van der Ent3, Cristina Gonnelli1

14 October 2025

Taxonomic status of taxa belonging to the genus Silene (Caryophyllaceae) in the Flora of Türkiye

Kemal Yildiz

There are approximately 870 species of the Silene L. (Transplant) genus on the world, 145 species (167 taxa) grow in the Flora of Türkiye. The gene center of the genus is Anatolia and its surroundings. Numerous taxonomic studies have been conducted on the genus. In this study, a study covering the whole of Türkiye was conducted. Previously collected plant samples were examined from 28 herbariums from Turkey, six from outside Turkey and 11 online sites, and the taxonomic status of the taxa was clarified. The descriptions of the species were expanded, seeds and pollen were examined with scanning electron microscope (SEM). With our research, the validity status of the species, new recorded species confirmed for the Flora of Türkiye, taxonomic changes in the categories of some species, and endemism status were revealed. At the end of the study, two varieties and one subspecies (S. olympica var. erciyesdaghensis, S. caramanica var. idaea, S. confertiflora subsp. thiebautii) were found together with the synonyms of 29 taxa were identified as synonyms (S. amana, S. eminentis, S. aydosensis, S. brevicalyx, S. cirpicii, S. goksuensis, S. inclinata, S. koycegizensis, S. ispartensis, S. yildirimlii, S. olympica var. erciyesdaghensis, S. kucukodukii, S. sipylea, S. caramanica var. idaea, S. bitlisensis, S. konuralpiae, S. apetala, S. bithynica, S. bocquetiana, S. magenta, S. guerbuezii, S .karakotchanensis, S. pompeiopolitana, S. sangaria, S. sumbiliana, S. trinervia, S. choruhensis, S. confertiflora subsp. thiebautii, S. atropurpurea), 11 taxa are new species or new records (S. kemahensis, S. nemrutensis, etc.), 26 taxa have changed status or are synonymous (S .aegyptiaca subsp .ruderalis, S. araratica subsp. davisii, etc.), and 2 species (S. fuscata, S. fabaroides) are not in the Flora of Türkiye.

Phylogenetic signal and morphological diversity in North African Silene (Caryophyllaceae)

Melilia Mesbah1, Samira Mesbah2

Results revealed a striking contrast between metrics. Blomberg’s K values were consistently low, suggesting limited phylogenetic signal and high evolutionary lability, likely reflecting convergent evolution or rapid divergence of certain traits. In contrast, Pagel’s λ values were generally high (median ≈ 0.85), with likelihood ratio tests confirming that most traits retain a significant phylogenetic component, although often deviating from strict Brownian expectations. The Mantel test indicated a moderate but significant correlation (r ≈ 0.3, p < 0.01) between morphological and genetic distance matrices, showing that morphology partially mirrors phylogeny but is also shaped by other evolutionary processes.

Overall, our findings indicate that morphological evolution in Silene involves both phylogenetic conservatism and convergence. While morphology retains a detectable phylogenetic structure, several traits show repeated or rapid shifts, emphasizing the influence of local ecological pressures. This study underscores the value of integrating molecular phylogenies with morphological data to disentangle evolutionary processes shaping biodiversity in North African flora.

Recombination suppression through structural variation leads to sex chromosome evolution in the plant Silene exscapa

Fabien Duez1, Gwyneth Halstead-Nussloch2, Martin C. Fischer2, Alex Widmer2, Gabriel Marais3, Sandrine Maurice1, Jos Käfer1

Appearance of separate sexes is usually associated with the evolution of sex chromosomes. Dioecy evolved many times independently in angiosperms providing an opportunity to study dynamics of their evolution. Sex chromosomes evolve from autosomes through recombination suppression around a sex-determining locus. However, despite many theories explaining why recombination might be suppressed, little is known about how this actually happens. In their early stages of evolution, sex chromosomes have small, weakly divergent non-recombining regions making them hard to detect. We here focus on Silene exscapa, a species that evolved separate sexes recently and ask if it has sex chromosomes and what their characteristics are. We use a new haplotype-specific chromosome-level assembly of a female and a male plant to map whole-genome resequencing data from three different populations, and look for sex-specific SNPs, coverage differences, and synteny between the haplotypes. Amid a large amount of nucleotide and structural diversity, we detect a 1 Mbp long female-specific region on one of the chromosomes common to all three populations. It contains six W-specific genes without any Z counterpart. In the newly discovered sex chromosomes of Silene exscapa, recombination suppression seems to start with an insertion or deletion, instead of an inversion as classically assumed. We discuss these findings in the light of genome and sex chromosome evolution.

Functional Characterization of Sex-linked Transcriptional Regulator HANABA TARANU-like in Silene latifolia

Tomas Janicek

Describing sex-linked genes is crucial to understanding the evolution of dioecy. The recent assembly of the Silene genome now allows us to select candidate genes and begin assigning their functions. We focused on the sex-linked candidate gene Silene latifolia HANABA TARANU (SlHAN), identified based on its differential expression in male and female floral tissues. In Arabidopsis, HAN is described as a GATA transcriptional regulator expressed in the border region separating meristems and B-class floral organs (anthers and petals). We conducted a series of experiments to characterize SlHAN expression and function in Silene. Sequence analysis identified structural and epigenetic differences between the X and Y copies, with the Y allele showing signs of degeneration. RNA in situ hybridization revealed differences in gene expression between sexes during organ initiation. In addition, we observed strong expression later in development, particularly in the tapetum and tetrads during early pollen development in male and ovules in female flower. To assess its function, we generated amiRNA knock-down lines. Silencing of SlHAN produced phenotypes ranging from shortened internodes and loss of apical dominance to reduced fertility. Our findings provide functional insight into a sex-linked transcriptional regulator in Silene, opening new avenues for understanding the evolution of dioecy at the molecular level.