Biology subjects

Dufay, M.

Publications and source records attributed to Dufay, M..

3 recordsLinked to original sources

bioRxiv2026

The structure and evolution of sex chromosomes in an androdioecious species with two mating types.

Though flowering plants are ancestrally hermaphroditic, some species have evolved sexual specialization and are now composed of individuals expressing just one of their two reproductive functions (either male or female) together with co-sexual individuals. Androdioecy, the co-existence of males with hermaphrodites, is rare across the living world, but unusually common in species of the Oleaceae plant family. The mediterranean shrub Phillyrea angustifolia has a simple mendelian XY sex-determination system for androdioecy, but the underlying molecular determinants and the evolutionary history of the X and Y chromosomes remain unknown. The ability of males to by-pass the self-incompatibility phenotype expressed in hermaphrodites is essential to explain their high frequency in natural populations, but how the loci governing sex and self-incompatibility epistatically interact also remains unknown. To address these questions, we obtained full haplotype-resolved de novo chromosomal assemblies of P. angustifolia and its sister species P. latifolia. The sex-determining region in P. angustifolia spanned a fifth of chromosome 12, and was strikingly larger and more rearranged than that in P. latifolia. The male-specific region contains two putative sex-determining genes, ANDY1 and ANDY2, a tandem encoding two flowering-related transcription factors that arose by translocation followed by duplication of an autosomal gene before the two species diverged. Strikingly, this sex-determining region also contains a recent duplicate of the pollen allergen gene Ole-e1, which shows the strongest differential expression between the two self-incompatibility groups of hermaphrodites, hence establishing a direct molecular link between sex and self-incompatibility. Overall, our results provide novel insight on sex determination and the evolution of sex chromosomes in a plant lineage where the separation between sexes is still incomplete, and offer a possible mechanistic basis for the strong epistatic interaction between the sex and self-incompatibility determinants, with direct implication for how sex-ratios are established in nature.

evolutionary biology↗

bioRxiv2024

Traits related to pollination and mating result in diverse reproductive strategies in angiosperms

O_LIFlowering plants have many modes of sexual reproduction, notably varying from selfing to outcrossing, and from bisexual flowers to individuals with separate sexes (dioecy). These reproductive modes are associated with floral and life-history traits that have evolved together, making it difficult to interpret correlations between traits. C_LIO_LIWe analysed variation in 21 traits related to flowers, pollination, mating, sexual systems and life history from 361 species representative of flowering plant diversity. C_LIO_LIOutcrossing was mainly found among long-lived, large-stature plants, but hermaphroditic outcrossers and dioecious species appeared as largely non-overlapping strategies in the trait space. Level of floral investment was the main difference between these strategies, with dioecious species having generally smaller, less rewarding flowers, a pattern that also occurred in biotically pollinated species. C_LIO_LIThis multi-trait study shows that pollination can be achieved in many, often contrasting, ways. Despite extensive variation in reproductive traits, dioecy stands out as being linked to floral traits primarily, while correlations with lifespan and dispersal traits appear spurious. We provide a conceptual framework based on lifespan, floral investment, and sexual separation that can be used to integrate pollination, reproduction and plant growth in future research on plant evolution and ecology. C_LI

evolutionary biology↗

bioRxiv2021

Effects of sexual dimorphism on pollinator behaviour in a dioecious species

Floral traits often display sexual dimorphism in insect-pollinated dioecious plant species, with male individuals typically being showier than females. While this strategy is theorized to be optimal when pollinators are abundant, it might represent a risk when they become scarce, because the disproportionately high number of visits on the most attractive sex, males, might preclude efficient pollen transfer from males to females. Here, the effect of sexual dimorphism on pollination efficiency was assessed in experimental arrays of dioecious Silene dioica that were exposed to one frequent visitor of the species, Bombus terrestris, and that differed in the magnitude of sexual dimorphism for either flower number or flower size. While flower size dimorphism did not impact pollination efficiency, we found that flower number dimorphism negatively affected the number of visits on female plants, on female flowers and on the number of female flowers visited after a male flower. However, flower number dimorphism had no effect on the number of pollen grains deposited per stigma, presumably because the decrease in the number of visits to female flowers was compensated by a higher number of pollen grains deposited per visit.

ecology↗