Meiotic adaptation to allopolyploidy

Introduction

Hybridization between related species resulting in allopolyploidy is ubiquitous in the evolutionary history of plants. Such nascent allopolyploids face the challenge of ensuring accurate chromosome segregation during meiosis in the presence of related, but non-identical chromosome sets (called homoeologues), inherited from the allopolyploid’s progenitors.

Importance of Crossover Formation

Essential for fertility, this relies upon the formation of physical connections (crossovers) between homologous chromosomes, while crossovers between homoeologues - that could lead to aneuploidy - must be prevented. Meiotic stability in the allopolyploid context thus requires a tight control of recombination partner choice.

Evolutionary Context

The existence of highly fertile natural allopolyploids shows that solutions exist and have arisen many times during evolution, but the mechanisms involved remain poorly understood.

Research Goals

My goal is to elucidate the evolutionary processes of meiotic stabilization of nascent allopolyploids, with a special emphasis on the molecular mechanisms that prevent recombination between homoeologous chromosomes.

Proposed Methodology

I propose to recreate in the lab the natural hybridization that happened ~16 Kya between A. thaliana and A. arenosa leading to Arabidopsis suecica in order to characterize the mechanisms underlying the evolution of the young allopolyploids over the first generations as they acquire meiotic stability and full fertility.

Project Objectives

The proposed project has three main objectives:

1. Map and characterize genome-wide recombination between homoeologues.
2. Identify the factors that control homoeologous pairing and recombination.
3. Elucidate how this control is progressively set up in newly formed allopolyploids.

Potential Impact

Our studies have the potential to bring new and fundamental insights on the evolutionary processes enabling meiotic stabilization of nascent allopolyploids and to contribute to polyploid crop improvement through knowledge transfer to plant breeding programs.