Biology subjects

Postel, Z.

Publications and source records attributed to Postel, Z..

3 recordsLinked to original sources

bioRxiv2025

Genomic studies in Linum shed light on the evolution of the distyly supergene and the molecular basis of convergent floral evolution

O_LIDistyly, an example of convergent evolution, is governed by a supergene called the S- locus. Recent studies highlight similar genetic architectures of independently evolved S-loci, but whether similar regulatory pathways underlie convergent evolution of distyly remains unclear. C_LIO_LIWe examined the evolution of supergenes and mechanisms underlying distyly in Linum species that diverged [~]33 Mya. Using haplotype-resolved genomes and population genomics, we identified and characterized the S-loci of Linum perenne (distylous) and Linum grandiflorum (style length dimorphic), and compared them to that of Linum tenue (distylous). We then tested for a conserved hormonal mechanism regulating style length polymorphism in Linum. C_LIO_LIHemizygosity in short-styled individuals is a shared feature of the Linum S-locus supergene, though its size, gene content, repeat elements, and extent of recombination suppression vary greatly among species. Two distyly candidate genes, TSS1 (style length) and WDR-44 (anther height/pollen self-incompatibility) are conserved at the C_LIO_LIS-locus. Consistent with a brassinosteroid-dependent role of TSS1, epibrassinolide treatment revealed a conserved, morph-specific effect on style length. C_LIO_LIS-locus genetic architecture, key S-locus genes and mechanisms regulating style length remain conserved >30 Mya in Linum. In combination with findings from other systems, our results suggest that the brassinosteroid pathway frequently contributes to style length polymorphism. C_LI

evolutionary biology↗

bioRxiv2023

Genomic analyses elucidate the causes and consequences of breakdown of distyly in Linum trigynum

Distyly is an iconic floral polymorphism governed by a supergene, which promotes efficient pollen transfer and outcrossing through reciprocal differences in the position of sexual organs in flowers, often coupled with heteromorphic self-incompatibility (SI). Distyly has evolved convergently in multiple flowering plant lineages, but has also broken down repeatedly, often resulting in homostylous, self-compatible populations with elevated rates of self-fertilization. Here, we aimed to study the genetic causes and genomic consequences of the shift to homostyly in Linum trigynum, which is closely related to distylous Linum tenue. Building on a high-quality genome assembly, we show that L. trigynum harbors a genomic region homologous to the dominant haplotype of the distyly supergene conferring long stamens and short styles in L. tenue, suggesting that loss of distyly first occurred in a short-styled individual. In contrast to homostylous Primula and Fagopyrum, L. trigynum harbors no fixed loss-of-function mutations in coding sequences of S-linked distyly candidate genes. Instead, floral gene expression analyses and controlled crosses suggest that mutations downregulating the S-linked LtWDR-44 candidate gene for male SI and/or anther height could underlie homostyly and self-compatibility (SC) in L. trigynum. Population genomic analyses of 224 whole-genome sequences further demonstrate that L. trigynum is highly self-fertilizing, exhibits significantly lower genetic diversity genome-wide, and is experiencing relaxed purifying selection and less frequent positive selection on nonsynonymous mutations relative to L. tenue. Our analyses shed light on the loss of distyly in L. trigynum, and advance our understanding of a common evolutionary transition in flowering plants.

evolutionary biology↗

bioRxiv2023

Rapid establishment of species barriers in plants compared to animals

Speciation, the process through which new reproductively isolated species emerge from ancestral populations, occurs due to the gradual accumulation of barriers to gene flow within genomes. To date, the notion that interspecific genetic exchange occurs more frequently between plant species than animals species has gained a strong footing in the scientific discourse. By examining the dynamics of gene flow across a continuum of divergence in both kingdoms, we observe the opposite relationship: plants experience less introgression than animals at the same level of genetic divergence, suggesting that species barriers are established more rapidly in plants. This pattern raises questions about which differences in microevolutionary processes between plants and animals influence the dynamics of reproductive isolation establishment at the macroevolutionary scale. One Sentence SummaryGenetic exchange is more frequent between animal species than plants, challenging historical views.

evolutionary biology↗