Abstracts

12 October 2026

Adapting to extreme environments: rapid evolution of heavy metal tolerance in Silene

Sarah Coates 1,2

1 University of Sheffield, UK
2 Bangor University, UK

In plants, closely related but distinct species often hybridise, which enables the introduction of novel genetic variation through repeated backcrossing (introgression). This process may be a source of genetic variation that increases fitness, which could fuel rapid, repeated adaptation across species. However, the relative contribution of introgression to (non) parallel adaptation within and between species is still debated. We quantified the degree of parallel adaptation across multiple biological levels in response to metal pollution within and between two closely related plant species in the Silene genus, S. uniflora and S. vulgaris. We also determined whether repeated adaptation across S. uniflora and S. vulgaris, and within S. uniflora, has been fuelled by introgression from S. vulgaris. We found limited parallelism at the level of genomic loci between S. uniflora and S. vulgaris, although this was greater for genes and gene functions. Therefore, parallelism in adaptation at a phenotypic level and functional level between species is mainly driven by species specific genetic variants. We found some evidence for adaptive introgression between mine adapted S. vulgaris and one mine-adapted S. uniflora population in Wales. However, no variants or genes shared signatures of selection between the two species, nor was there evidence of repeated adaptive introgression into S. uniflora. This suggests that introgression has not contributed to parallel adaptation within or between species. Instead, repeated adaptation at a genetic level is like to be the result of convergent mutations or shared standing variation.

Geometric morphometrics of the calyx in Silene arabica and its relatives

Amir Hossein Ekhtiarian, Farzaneh Jafari

Department of Biology, Faculty of Basic Sciences, Lorestan University, Khorramabad, Iran

Cryptic and pseudo-cryptic species represent a hidden component of biodiversity that requires discovery. Their discovery is crucial for effective conservation and for advancing our understanding of speciation mechanisms. The Silene villosa complex including three species (S. arabica, S. villosa and S. wendelboi) which the molecular data supported the species distinction can be considered as pseudo-cryptic species complex. We employed geometric morphometrics to assess calyx shape and traditional morphometrics to measure calyx length, calyx width, and pedicel length, in order to determine whether these traits can distinguish these species. We created a dataset comprising 456 specimens, of which those 118 belong to S. arabica, 245 to S. villosa and 93 to S. wendelboi. We used 6 landmarks and 20 semi-landmarks to analyze the patterns of morphological variation in the species. A generalized Procrustes analysis (GPA) was applied to the dataset. To test for significant differences in calyx shape and size among the three species, a Procrustes ANOVA was performed in MorphoJ (version 1.07a; Klingenberg, 2011). Principal component analysis (PCA) was used to explore and summarize patterns of calyx shape variation, while canonical variate analysis (CVA) was employed to visualize morphological differences among the complex.

Procrustes ANOVA revealed significant differences among the three species for both centroid size and calyx shape (P < 0.0001). Principal component analysis showed that the first two components accounted for the majority of total shape variation, indicating that morphological variation is concentrated along a few major axes. Canonical variate analysis further confirmed strong among-group differentiation, with the first canonical variate explaining most of the variation. Mahalanobis distances between all species pairs were highly significant (P < 0.0001), and discriminant function analysis showed generally high classification accuracy, although the level of correct assignment varied among species pairs, with one pair showing noticeably lower discrimination than the others.

The three species are morphologically distinct in calyx shape and size, but the relatively lower classification accuracy and smaller morphological distance between two of the species indicate considerable shape overlap. This pattern is consistent with the hypothesis that these species are pseudocryptic, exhibiting morphological differences that are visually detectable but were previously not considered diagnostic for species separation.

Comparative study of sexual dimorphism in the Silene genus : impact of pollination mode and age of dioecy

Alexis Ryo 1,2 ; Aline Muyle 1 ; Mathilde Dufay 2

1 Institut des Sciences de l'Evolution de Montpellier (ISEM)
2 Centre d’Ecologie Fonctionnelle et Evolutive (CEFE) Montpellier

Sexual dimorphism is observed in many dioecious plant species (i.e. with separate sexes), in both floral and vegetative traits. However, the forces that promote or constrain the evolution of sexual dimorphism and their respective contributions remain relatively unexplored. First, selection on fertility is one of the forces that promote the evolution of sexual dimorphism, by favoring higher quantity and quality of gamete production. Since the requirements of male and female gametes differ, this can lead to dimorphism in traits related to gamete production or in traits involved in the extraction of compounds necessary for gamete production. Second, sexual selection can also lead to the evolution of sexual dimorphism, by affecting traits that control access to reproduction. As in animals, this selective force is expected to be stronger in male plants, whose reproductive success is expected to be more sensitive to the number of mates. For traits under sexual selection, we can expect that the nature of the dimorphic traits and the intensity of dimorphism will depend on the pollination system (e.g., plant size is expected to be dimorphic in anemophilous plants, while flower size and color dimorphism may be more prevalent in entomophilous plants). Finally, the time since when separate sexes evolved may also influence the degree of dimorphism : lineages in which the sexes have been separate for a longer period of time may exhibit more pronounced sexual dimorphism. Our study examines nine species of dioecious plants, all belonging to the genus Silene. These species are divided into two independent lineages, with contrasted age of transition to dioecy. Furthermore, pollination mode may also vary : at least one species is known to be partially wind-pollinated, five others are known to be predominantly insect-pollinated, and the remaining species exhibit characteristics suggesting they are wind-pollinated, although this has yet to be experimentally confirmed. For each species, we measured sexual dimorphism in vegetative traits (SLA, LDMC, dry weight) and reproductive traits (number and size of flowers). Comparing the direction and intensity of sexual dimorphism among our species allows us to explore the mechanisms that determine the evolution of sexual dimorphism in plants.

Phenotypic variation in Silene nutans in Western Europe: a mirror of phylogeographic history?

Garance Blondel1, Sarah Lefebvre1, Nausicaa Noret1, Isabelle De Cauwer², Pascal Touzet², Fabienne Van Rossum1,3,4

1 Laboratoire d’Ecologie végétale et Biogéochimie, Université libre de Bruxelles, Brussels, Belgium
2 University Lille, CNRS, UMR 8198—Evo-Eco-Paleo, Lille F-59000, France
3 Research Department, Meise Botanic Garden, Meise, Belgium
4 Service général de l’Enseignement supérieur et de la Recherche scientifique, Fédération Wallonie-Bruxelles, Brussels, Belgium

In Western Europe, Silene nutans consists of four distinct genetic lineages (E1, W1, W2 and W3), identified based on nuclear microsatellites and plastid SNPs, and harbouring multiple, sometimes asymmetric, pre- and postzygotic reproductive isolation barriers. Genetic divergence reflects past climate events and can be associated with allopatry, with genetic lineages having evolved in separate glacial refugia, diverging 760 000–300 000 years ago. We investigated fruit and seed size and shape of these four lineages in Western Europe (United Kingdom, France, Belgium, the Netherlands, Luxembourg and Germany), compared Belgian and foreign populations of E1 and W1 to test whether the unique lineage–edaphic association observed in the secondary contact zone of southern Belgium is accompanied by additional morphological divergence, and assessed the relative contributions of genetic differentiation (based on 13 microsatellite loci), geographic location and environmental conditions (climate, bedrock type, soil properties and Ellenberg indicator values for vegetation). Capsule size (length, width and volume), shape (length-to-width ratio) and carpophore length were measured in 150 populations, and seed size (length, width, perimeter and area) and shape (length-to-width ratio, circularity and solidity and outline shape quantified by elliptic Fourier coefficients) were measured in 60 populations.

Characters discriminating the four lineages were identified: W1 and W2 had larger capsules and seeds than E1 and W3. E1 had the smallest capsules, while W3 had more ovoid capsules than E1 and shorter carpophores than W1. Seed circularity discriminated all four lineages and elliptic Fourier analysis revealed differences in seed outline, with E1 and W2 showing less and more reniform seeds, respectively. Belgian E1 and W1 populations produced smaller capsules than foreign populations, whereas Belgian W1 populations had larger seeds, suggesting additional morphological differentiation related to the unique lineage–edaphic association in southern Belgium. Variation partitioning showed that genetic differentiation among lineages explained the highest proportion of capsule and seed morphological variation, suggesting that the evolutionary processes underlying genetic divergence (restricted gene flow, mutation, genetic drift and selection) also shaped their morphology.

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13 October 2026

Meiosis of sex chromosomes in Silene latifolia

Václav Bačovský1, Pavla Novotná1,2, Dylan Phillips3, Lucie Horáková1, Jana Kružlicová1,2, Bohuslav Janoušek1, Roman Hobza1, Radim Čegan1

1 Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 65 Brno, Czech Republic
2 National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
3 Department of Life Science, Aberystwyth University, Penglais, Aberystwyth, Ceredigion SY23 3DA, UK

Meiotic pairing and synapsis are coordinated processes that ensure the accurate segregation of homologous chromosomes into the next generation. In species with heteromorphic sex chromosomes, pairing is often restricted to pseudoautosomal regions (PARs), regions of sequence homology that enable X–Y (or Z–W) recognition and recombination. Since the discovery of sex chromosomes in Silene latifolia by Kathleen Blackburn, its X and Y chromosomes have attracted considerable attention as a model for studying the origin and evolution of plant sex chromosomes. Nevertheless, their precise pairing and synaptic behaviour during meiosis have remained comparatively underexplored. Taking advantage of recent improvements in chromosome preparation and super-resolution microscopy, we investigated chromosome pairing and synapsis throughout prophase I in S. latifolia and the related species S. vulgaris. We followed synapsis of autosomes and sex chromosomes in diploid plants and compared physical associations among sex chromosomes in triploid and autotetraploid individuals carrying different X:Y complements. Meiotic associations observed during prophase I were further evaluated in chromosome spreads at metaphase I using an X/Y oligo-painting probe. By physically localizing class I crossovers (COs) at pachytene, we found CO numbers comparable to those reported in Arabidopsis and maize, while differences were observed between diploid and higher-ploidy S. latifolia. Super-resolution analysis further revealed extensive asynapsis of the non-recombining regions of the X and Y chromosomes, whereas additional sex chromosomes in XXXY and XXYY individuals participated in more complex multivalent configurations. Together, our observations provide a detailed view of how X and Y chromosomes interact during meiosis and provide further insight into the consequences of restricted X–Y recombination for meiotic chromosome behaviour and sex-chromosome evolution in S. latifolia.

GSFY negatively regulates a SUPERMAN-like gene to suppress gynoecium development in male Silene latifolia

Vojtěch Hudzieczek, Tomáš Janíček, Dmytro Abramov, Václav Bačovský, Radim Čegan, Šárka Kobzová, Magda Soukupová, Boris Vyskot, Roman Hobza

Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences v.v.i., Kralovopolská 135, Brno, 612 00, Czech Republic

Silene latifolia is a dioecious plant with an XY sex chromosome system, in which Y-linked genes control male floral development. We investigated the role of GSFY (GYNOECIUM SUPPRESSION FACTOR Y), a Y-linked homolog of CLAVATA3, in the suppression of female organ development. GSFY is not expressed in artificially generated hermaphroditic XY plants, which instead show ectopic expression of a SUPERMAN-like gene. Moreover, ectopic overexpression of SUPERMAN-like in male plants induces hermaphroditic flower development. These results suggest that GSFY acts upstream as a negative regulator of SUPERMAN-like expression, thereby contributing to gynoecium suppression in male flowers. Our findings identify a regulatory interaction between a Y-linked developmental regulator and an autosomal gene and provide new insights into the molecular control and evolution of dioecy in S. latifolia.

Epigenetic reprogramming guides sexual dimorphism during floral development in Silene latifolia

Tomas Janicek, Vojtech Hudzieczek, Hana Polasek-Sedlackova, Marie Kratka, Roman Hobza, Vaclav Bacovsky

Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 65 Brno, Czech Republic

In Silene latifolia, sex determination has been approached primarily as a genetic problem: the sex-determining regions of the Y have been mapped, candidate genes identified, and chromosome degeneration dated. Far less is known about where and when these instructions are read out as chromatin states in the developing flower. To address this, we developed a microscopy approach for the statistical evaluation of immunostaining in histological sections at single-cell resolution. We selected two histone modifications, H3K4me1 and H3K9me2, together with Ser2-phosphorylated RNA Polymerase II (Pol II-S2ph) as a marker of active transcription, and mapped them across stage-matched male and female floral meristems, from the onset of sex determination through floral primordia establishment to anther and gynoecium differentiation. To move beyond the threshold-based segmentation that limits classical microscopy, we combined high-content imaging with AI-assisted nuclei segmentation, assigning thousands of individual nuclei per section to meristematic zones and floral organs and comparing the sexes cell population by cell population. This yielded two to three times more scored nuclei per section than threshold-based segmentation. Comparing male and female meristems, two patterns emerged. First, H3K4me1 and Pol II-S2ph signal was enriched in female meristems during sex determination, the effect being larger for Pol II-S2ph. Notably, this enrichment was localized to the region that gives rise to the gynoecium primordia, highlighting the role of transcriptional activity in this crucial cell population. Second, H3K9me2 enrichment marked cell-type transitions, most prominently in young anthers, a tissue about to enter sporogenesis. Together, our findings reveal sex-specific differences in chromatin state and transcriptional activity in the developing floral meristem of S. latifolia, and demonstrate a new microscopy-based approach for statistically evaluating immunostaining of histological sections, applicable across plant species.

Transcriptomic analysis of Silene latifolia slap3 mutants during Microbotryum lychnidis-dioicae infection

Dérica G. Tavares 1, Vojtěch Hudzieczek 2, Michael H. Perlin 1

1 University of Louisville, USA
2 Institute of Biophysics of the Czech Academy of Sciences, Czech Republic

The SlAP3 gene in Silene latifolia has two alleles linked to the X and Y sex chromosomes and plays a crucially important role in floral development. While SlAP3X supports expression associated with general aspects of petal or flower development, SlAP3Y is expressed in developing stamens, indicating a specialized role in male flower function. In this study, we evaluated the transcriptome of S. latifolia slap3 mutants during infection by Microbotryum lychnidis-dioicae (MVLG), an anther-smut fungus that sterilizes its host by replacing pollen with its spores. Homozygous seeds for slap3 mutations were used and infected with MVLG strains p1A1 and p1A2. RNA was isolated from flower buds of uninfected plants and from tissues of infected plants, then sequenced for transcriptome analysis. All infected plants remained in the vegetative stage with minimal growth, and infection status was confirmed via qPCR for fungal gDNA detection. A total of 5,412 differentially expressed genes (DEGs) were observed, comprising 2,565 up-regulated and 2,847 down-regulated genes. The genes LOC141600182 and LOC141596908, that encode a cysteine proteinase and a mucunain-like proteinase, respectively, were upregulated and, these are known to play a role in plant immunity by regulating programmed cell death and responses to stress. The genes LOC141656703, LOC141596978, and LOC141656785, corresponding, respectively, to a bark storage protein A-like protein, a beta-amylase, and a jasmonate-induced protein homolog, were downregulated; these genes are important for plant growth, highlighting a strategic metabolic shift known as the growth-defense trade-off. The results show the upregulation of genes related to defense and stress response during MVLG infection, alongside the downregulation of genes important for development, which appears to constitute a strategic metabolic shift prioritizing active defense over growth in S. latifolia slap3 mutants.