Title of the traineeship: Origin and evolution of sex chromosomes in Silene
Traineeship supervisor: Pascal Touzet
Other(s) supervisor(s): Mathieu Genete
Laboratory: UMR 8198 – Evo-Eco-Paleo, Univ. Lille
Phone number: 03.20.33.59.23
Email: pascal.touzet@univ-lille.fr
SUBJECT OF THE TRAINEESHIP
Understanding the evolutionary and ecological processes that lead to the transition from a given breeding system to another is still a vivid question in evolutionary biology. In particular, the transition from hermaphroditism to dioecy (separated sexes) can be due to the evolution of a pair of an autosomal pair toward a pair of sex chromosomes, XY (females XX, males XY) or ZW (females ZW and males ZZ). Sex chromosomes are characterized by a reduction of recombination between X and Y or Z and W, with a subsequent degeneration of the Y or the W.
It is possible to assess the origin and the evolution of sex chromosomes in plants due to the fact that they are generally more recent that their counterparts in animals. This is the case in Silene (Caryophyllaceae), where several independent emergences of sex chromosomes have occurred (Muyle et al. 2021):
– in Subgenus Behenanta, an XY system where in S. latifolia, the sex chromosomes have been recently sequenced (Yue et al. 2023; Moraga et al. 2023).
– in Subgenus Silene, in Otites section, where two different sex chromosome pairs have been documented: a XY pair in S. colpophylla and S. pseudotites, having evolved from a different autosomal pair than S. latifolia ones, a ZW pair in S. borysthenica and S. otites, derived from a third autosomal pair (Balounova et al. 2019; Martin et al. 2019).
The present project aims to understand the origin of the ZW pair by using a comparative genetic mapping framework using S. nutans as the map reference, a hermaphroditic species belonging to the same subgenus as S. otites. The trainee will use NGS data from gene captures to build the genetic maps of S. nutans and S. otites, and phenotype the sex of the S. otites mapping population. In addition, the trainee will participate on the measurement of fitness related traits in a collection of several species of the Otites section in the context of the project SeCCSi, that aims to evaluate the involvement of sex chromosomes in speciation in the Otites section.
The present traineeship could be followed by a 3-year PhD project that is already fully financed by the SeCCSi project (ANR AAP 2023, PI: P. Touzet).
References:
Balounova et al. 2019. Evolution of sex determination and heterogamety changes in section Otites of the genus Silene. Sci Rep 9, 1045. https://doi.org/10.1038/s41598-018-37412-x
Martin et al. 2019. Evolution of Young Sex Chromosomes in Two Dioecious Sister Plant Species with Distinct Sex Determination Systems. Genome Biology and Evolution 11, 350–361. https://doi.org/10.1093/gbe/evz001
Moraga et al. 2023. The Silene latifolia genome and its giant Y chromosome. bioRxiv preprint doi: https://doi.org/10.1101/2023.09.21.558754;
Muyle, et al. 2021. Dioecy Is Associated with High Genetic Diversity and Adaptation Rates in the Plant Genus Silene. Molecular Biology and Evolution 38, 805–818. https://doi.org/10.1093/molbev/msaa229
Yue et al. 2023. The origin and evolution of sex chromosomes, revealed by sequencing of the Silene latifolia female genome. Current Biology 33, 1-11.
Commentaires récents