Evolution of Floral MADS-Box Genes through Tandem and Whole-Genome Duplications

MADS-box genes perform a diverse array of functions in flowering plants. Yet, despite that this family of transcription factors has been and still is extensively researched, not much is known about its deep origin. This talk will focus on our recent progress in elucidating the deep evolution of floral MADS-box genes. Using a combination of genome synteny and phylogenetic reconstructions, we were able to piece together an evolutionary scenario of tandem and subsequent whole-genome duplications that explains the origin of several angiosperm MADS-box subfamilies. Additionally, we showed that FLOWERING LOCUS C-like genes are not core-eudicot specific but are also present in monocots. We hypothesized that these ancient whole-genome duplications near the origin of the angiosperms could have had a profound effect on the floral MADS-box protein-protein interaction (PPI) network. Using ancestral sequence reconstruction, we resurrected ancestral MADS-box proteins from just before and after the gene duplications prevalent at the origin of the angiosperms in the B-, C/D- and E-class gene lineages and assessed their PPI capacity using the yeast n-hybrid system. Doing so, we reconstructed the ancestral PPI network and retraced interaction changes due to the duplications close to the origin of the angiosperms. We propose that these rewiring events could have played a role in the origin of floral organ identities.