02/04/21 - Séminaire (en ligne) de Malika AINOUCHE
Polyploidy (resulting from whole genome duplication, WGD) leads to the presence of more than two homologous chromosome sets in the nucleus, and has long been known as a common speciation mechanism in plants. Since the analyses of the first Angiosperm genome sequences twenty years ago, accumulating plant genome data have documented the recurrence of polyploidy across all plant lineages, with older events dating back to seed plant ancestry. The history of all modern plant genomes (including “diploids”) appears punctuated by superimposed rounds of polyploidization, fractionation and diploidization. How plant organisms respond to challenges such as WGD and genome merger (following hybridization in the context of allopolyploidy), what are early and long term processes involved in the adaptive success of polyploids, represent major questions in evolutionary biology. The polyploid grass genus Spartina which includes several species considered as ecosystem engineers on salt marshes, represents an excellent model system to explore such questions at various evolutionary time scales (i.e. neopolyloidy, mesopolyploidy and paleopolyploidy). Challenges in documenting the deep history of superimposed WGD events, deciphering the molecular mechanisms involved in phenotypic novelties and species expansion (e.g. in invasive species) will be presented.