Format: ORAL

Miguel Campos Cceres1,2, Rubn Sancho1,2,3, Bruno Contreras-Moreira2,3, Ernesto Prez-Collazos1,2, Li Lei4, John Vogel4, Pilar Cataln1,2

1 Escuela Politécnica Superior de Huesca. Universidad de Zaragoza. Carretera de Cuarte Km 1. E-22071 Huesca. Spain. mccaceres@unizar.es, rsancho@unizar.es, ernextop@unizar.es, pcatalan@unizar.es 2 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR, CSIC) 3 Estación Experimental Aula Dei-CSIC, 50059, Zaragoza, Spain. bcontreras@eead.csic.es 4 DOE Joint Genome Institute, Berkeley, CA 94720, USA. LiLei@lbl.gov, JPVogel@lbl.gov

Pangenome analyses help to unveil the genome landscape and the evolutionary traits and trajectories of complex plant groups. We generated a large pangenome for 282 native Mediterranean representatives of the diploid-allopolyploid Brachypodium grass model system (118 B. distachyon-2x, 35 B. stacei-2x, 129 B. hybridum-4x) accounting for a total of 411 assembled genomes and subgenomes. Filtered syntenic SNPs from whole (sub)genomes were used to reconstruct the evolutionary trajectory of the Brachy lineages and to perform population genomics.B. hybridum showed a general additive pattern of TEs in its two progenitor genomes, our analysis detected a slight proliferation of transposons in the allotetraploid compared to the diploids, probably as consequence of the allopolyploidization process. Maximum Likelihood (ML) and coalescent-based trees uncovered several genomic clusters in the diploids B. distachyon and B. stacei, which were shaped by evolutionary history and geography, and revealed three independent and recurrent origins for their derived allotetraploid B. hybridum from local parents. Population genomic structure also revealed three clusters for, respectively, the ancestral western Mediterranean and the two recent western and eastern Mediterranean hybridization events, and overall large homogeneities in both subgenomes. A thoroughgenomic analysis of intraspecific individuals exhibiting genetic admixture showed a homogeneous distribution of admixture markersacross all chromosomes suggesting a genome-wide level occurrence of admixture.