Evolution of Meiosis

Based on centromere organization, chromosomes are essentially classified into two main types, monocentric chromosomes with a single centromere domain per chromosome and holocentric chromosomes with multiple centromere domains distributed genome-wide. It is known that monocentric organisms show restricted or even non-meiotic recombination at and near centromeres (cold regions). Therefore, it is of particular interest to understand how meiotic recombination works in plants with holocentric chromosomes. Holocentric plants also show several adaptations during meiosis, e. g. chiasmatic and achiasmatic inverted meiosis, where homologs segregation is postponed to second meiosis. As holocentric plants developed several adaptations to bypass meiosis, they do not only offer an exciting model to understand how these adaptations take place during evolution but are also of interest for comparative biology. In our team, we aim to decipher the molecular mechanisms associated with meiotic adaptations observed in holocentric plants.

Our research will mainly focus on the model species (but not only) R. pubera (2n=10) and R. tenuis (2n=4). Taking advantage of cutting-edge technologies, we will develop several analyses aiming at the characterization of meiotic recombination rates and the role of meiotic proteins as well as the potential identification of new proteins involved in the evolution of meiotic adaptations observed in these organisms. Using holocentric plants as a model to understand how meiotic recombination is regulated at centromeric regions will potentially unveil new strategies to address meiotic recombination issues on monocentric organisms.

From left to right: Rhynchospora pubera, 1- Mitotic chromosomes showing line-like holocentromeres, 2- meiotic anaphase I showing segregation of sister chromatids with restructured cluster-centromeres, 3- zoomed view of 2, 4- meiotic metaphase II showing the postponed segregation of homologous chromatids. Chromatids (grey), CENH3 (red), tubulin (green).

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