Natural variation in sexual traits and gene expression between selfing and outcrossing Arabidopsis lyrata suggests sexual selection at work.

Flowering plants show significant diversity in sexual strategies, profoundly impacting the evolution of sexual traits and associated genes. Sexual selection is one of the primary evolutionary forces driving sexual trait variation, particularly evident during pollen-pistil interactions, where pollen grains compete for fertilization and females select mating partners. Multiple mating may intensify competition among pollen donors for siring, while in contrast, self-fertilization reduces sire-sire competition, relaxing the sexual selection pressure.

Darwin's 'mystery of mysteries': the role of sexual selection in plant speciation.

Sexual selection is considered one of the key processes that contribute to the emergence of new species. While the connection between sexual selection and speciation has been supported by comparative studies, the mechanisms that mediate this connection remain unresolved, especially in plants. Similarly, it is not clear how speciation processes within plant populations translate into large-scale speciation dynamics.

Epigenetic targeting of transposon relics: beating the dead horses of the genome?

Transposable elements (TEs) have been seen as selfish genetic elements that can propagate in a host genome. Their propagation success is however hindered by a combination of mechanisms such as mutations, selection, and their epigenetic silencing by the host genome. As a result, most copies of TEs in a given genome are dead relics: their sequence is too degenerated to allow any transposition.

Eunuchs or Females? Causes and Consequences of Gynodioecy on Morphology, Ploidy, and Ecology of L. (Caryophyllaceae).

Plant speciation results from intricate processes such as polyploidization, reproductive strategy shifts and adaptation. These evolutionary processes often co-occur, blurring their respective contributions and interactions in the speciation continuum. Here, relying on a large-scale study, we tested whether gynodioecy triggers the divergent evolution of flower morphology and genome between sexes, and contributes to the establishment of polyploids and colonization of ecological niches in .

On the origin of the widespread self-compatible allotetraploid Capsella bursa-pastoris (Brassicaceae).

Polyploidy, or whole-genome duplication, is a common speciation mechanism in plants. An important barrier to polyploid establishment is a lack of compatible mates. Because self-compatibility alleviates this problem, it has long been hypothesized that there should be an association between polyploidy and self-compatibility (SC), but empirical support for this prediction is mixed.

Winter-dormant shoot apical meristem in poplar trees shows environmental epigenetic memory.

Trees have a long lifespan and must continually adapt to environmental pressures, notably in the context of climate change. Epigenetic mechanisms are doubtless involved in phenotypic plasticity and in stress memory; however, little evidence of the role of epigenetic processes is available for trees growing in fields. Here, we analyzed the possible involvement of epigenetic mechanisms in the winter-dormant shoot apical meristem of Populus × euramericana clones in memory of the growing conditions faced during the vegetative period.

Changes in the epigenome and transcriptome of the poplar shoot apical meristem in response to water availability affect preferentially hormone pathways.

The adaptive capacity of long-lived organisms such as trees to the predicted climate changes, including severe and successive drought episodes, will depend on the presence of genetic diversity and phenotypic plasticity. Here, the involvement of epigenetic mechanisms in phenotypic plasticity toward soil water availability was examined in Populus×euramericana. This work aimed at characterizing (i) the transcriptome plasticity, (ii) the genome-wide plasticity of DNA methylation, and (iii) the function of genes affected by a drought-rewatering cycle in the shoot apical meristem.

Endosperm-based hybridization barriers explain the pattern of gene flow between Arabidopsis lyrata and Arabidopsis arenosa in Central Europe.

Based on the biological species concept, two species are considered distinct if reproductive barriers prevent gene flow between them. In Central Europe, the diploid species Arabidopsis lyrata and Arabidopsis arenosa are genetically isolated, thus fitting this concept as "good species." Nonetheless, interspecific gene flow involving their tetraploid forms has been described.

Endosperm-based postzygotic hybridization barriers: developmental mechanisms and evolutionary drivers.

The endosperm is a nourishing tissue that serves to support embryo growth. Failure of endosperm development will ultimately cause embryo arrest and seed lethality, a phenomenon that is frequently observed upon hybridization of related plant species or species that differ in ploidy. Endosperm-based interspecies or interploidy hybridization barriers depend on the direction of the hybridization, causing nonreciprocal seed defects.

Non-reciprocal Interspecies Hybridization Barriers in the Capsella Genus Are Established in the Endosperm.

The transition to selfing in Capsella rubella accompanies its recent divergence from the ancestral outcrossing C. grandiflora species about 100,000 years ago. Whether the change in mating system was accompanied by the evolution of additional reproductive barriers that enforced species divergence remained unknown.

Evolution and function of epigenetic processes in the endosperm.

The endosperm is an ephemeral tissue surrounding the embryo that is essential for its development. Aside from the embryo nourishing function, the endosperm serves as a battlefield for epigenetic processes that have been hypothesized to reinforce transposable element silencing in the embryo. Specifically, global DNA demethylation in the central cell may serve to produce small RNAs that migrate to egg cell and embryo to induce de novo DNA methylation.

Epigenetic mechanisms of postzygotic reproductive isolation in plants.

Hybrid incompatibility is generally viewed as a consequence of negative epistatic interactions between alleles that do not cause negative fitness effects in their parents. Substantial evidence in support of the model has accumulated over recent years. Nevertheless, there is evidence that hybrid incompatibility can have an epigenetic basis and results from deregulated small RNAs (sRNAs), causing changes in DNA methylation and transposable element (TE) activation.

Embryo and endosperm, partners in seed development.

Angiosperm seeds are the major source of human calories, generating a pressing need to understand the underlying processes governing seed growth and development. They are composed of the two fertilization products, embryo and endosperm surrounded by the maternally derived seed coat. The successful interaction of all three seed components is a requirement for seeds to complete their development and to produce viable embryos that are competent to establish a new sporophytic generation.

Epigenetic regulation of adaptive responses of forest tree species to the environment.

Epigenetic variation is likely to contribute to the phenotypic plasticity and adaptative capacity of plant species, and may be especially important for long-lived organisms with complex life cycles, including forest trees. Diverse environmental stresses and hybridization/polyploidization events can create reversible heritable epigenetic marks that can be transmitted to subsequent generations as a form of molecular "memory". Epigenetic changes might also contribute to the ability of plants to colonize or persist in variable environments.

Identification of differentially methylated regions during vernalization revealed a role for RNA methyltransferases in bolting.

Sugar beet (Beta vulgaris altissima) is a biennial root crop with an absolute requirement for cold exposure to bolt and flower, a process called vernalization. Global DNA methylation variations have been reported during vernalization in several plants. However, few genes targeted by DNA methylation during vernalization have been described.

Methylome of DNase I sensitive chromatin in Populus trichocarpa shoot apical meristematic cells: a simplified approach revealing characteristics of gene-body DNA methylation in open chromatin state.

DNA methylation is involved in the control of plant development and adaptation to the environment through modifications of chromatin compaction and gene expression. In poplar (Populus trichocarpa), a perennial plant, variations in DNA methylation have been reported between genotypes and tissues or in response to drought. Nevertheless, the relationships between gene-body DNA methylation, gene expression and chromatin compaction still need clarification.