Complex polyploid and hybrid species in an apomictic and sexual tropical forage grass group: genomic composition and evolution in Urochloa (Brachiaria) species

• DOI: 10.1093/aob/mcab147
• Publication Date: 2021-12-06T20:14:58Z
• Authors: Paulina Tomaszewska; Maria S Vorontsova; Stephen A Renvoize; Sarah Z Ficinski; Joseph Tohme; Trude Schwarzacher; Valheria Castiblanco; José J de Vega; Rowan A C Mitchell; J S (Pat) Heslop-...
• Keywords: Polyploid; Apomixis; Panicum; Genome size; Germ plasm; Brachiaria

Diploid and polyploid Urochloa (including Brachiaria, Panicum Megathyrsus species) C4 tropical forage grasses originating from Africa are important for food security the environment, often being planted in marginal lands worldwide. We aimed to characterize nature of their genomes, repetitive DNA genome composition polyploids, leading a model evolutionary pathways within group including many apomictic species.Some 362 grass accessions international germplasm collections were studied, ploidy was determined using an optimized flow cytometry method. Whole-genome survey sequencing molecular cytogenetic analysis used identify chromosomes genomes belonging 'brizantha' 'humidicola' agamic complexes U. maxima.Genome structures complex variable, with multiple ploidies compositions species, no clear geographical patterns. Sequence nine diploid enabled identification abundant genome-specific motifs. In situ hybridization combination genomic probes identified divergence allowed us discriminate different present polyploids.We suggest new coherent nomenclature present. develop evolution at whole-genome level showing processes evolution. support retention narrow species concepts brizantha, decumbens ruziziensis, do not consider diploids polyploids single as cytotypes. The results will be valuable making rational choices parents hybrids, assist use breeding selection improved sustainability agronomic potential, measuring conserving biodiversity grasslands.