Le vendredi 4 décembre 2015 à 10h15, amphi B, bâtiment 2, Campus de Beaulieu, UR1
Le vendredi 4 décembre 2015 à 10h15
, amphi B, bâtiment 2, Campus de Beaulieu, UR1Genomes within genomes within genomes: exploring the mysteries of polyploidy in plantsAbstract :
One of the signal realizations of the genomics era is that all flowering plants are multiply polyploid, varying only in the number and relative antiquity of whole genome doubling events. Gossypium, the cotton genus, exemplifies this recurrent, episodic polyploidization, and even includes neoallopolyploids that originated following a biological reunion 1-2 MYA of divergent diploids from different hemispheres. This serendipitous merger generated a spectrum of genomic responses, which serve as illustrative models for understanding evolutionary genomic processes following polyploidy. These include gene silencing, intergenomic gene conversion, and genome-wide disruption and modification of ancestral expression patterns. Allopolyploid formation induces massive alteration in gene expression and complex transcriptomic responses, and novel cytonuclear interactions. Duplicate gene expression changes are temporally partitioned into alterations arising immediately as a consequence of genomic merger and secondarily as a result of long-term evolutionary transformations in duplicate gene expression, the latter reflecting long-term evolutionary forces such as duplicate gene neofunctionalization and subfunctionalization. Recurrent polyploidy in plants is followed by many diverse genomic processes, occurring over time scales ranging from several generations to millions of years, that collectively lead to genome downsizing, genomic fractionation, and full chromosomal diploidiziation. A major challenge is to connect these long and short-term processes to adaptive evolution and the generation of biodiversity.
Contact : Jonathan WENDEL