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ToolsTomaszewska, Paulina, Vorontsova, Maria S., Renvoize, Stephen A., Ficinski, Sarah Z., Tohme, Joseph, Schwarzacher, Trude, Castiblanco, Valheria, De Vega, José J., Mitchell, Rowan A. C. and Heslop-Harrison, J. S. Pat (2023) Complex polyploid and hybrid species in an apomictic and sexual tropical forage grass group: Genomic composition and evolution in Urochloa (Brachiaria) species. Annals of Botany, 131 (1). pp. 87-108. ISSN 0305-7364
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Abstract
Background and Aims: Diploid and polyploid Urochloa (including Brachiaria, Panicum and Megathyrsus species) C4 tropical forage grasses originating from Africa are important for food security and the environment, often being planted in marginal lands worldwide. We aimed to characterize the nature of their genomes, the repetitive DNA and the genome composition of polyploids, leading to a model of the evolutionary pathways within the group including many apomictic species. Methods: Some 362 forage grass accessions from international germplasm collections were studied, and ploidy was determined using an optimized flow cytometry method. Whole-genome survey sequencing and molecular cytogenetic analysis were used to identify chromosomes and genomes in Urochloa accessions belonging to the 'brizantha' and 'humidicola' agamic complexes and U. maxima. Key Results: Genome structures are complex and variable, with multiple ploidies and genome compositions within the species, and no clear geographical patterns. Sequence analysis of nine diploid and polyploid accessions enabled identification of abundant genome-specific repetitive DNA motifs. In situ hybridization with a combination of repetitive DNA and genomic DNA probes identified evolutionary divergence and allowed us to discriminate the different genomes present in polyploids. Conclusions: We suggest a new coherent nomenclature for the genomes present. We develop a model of evolution at the whole-genome level in diploid and polyploid accessions showing processes of grass evolution. We support the retention of narrow species concepts for Urochloa brizantha, U. decumbens and U. ruziziensis, and do not consider diploids and polyploids of single species as cytotypes. The results and model will be valuable in making rational choices of parents for new hybrids, assist in use of the germplasm for breeding and selection of Urochloa with improved sustainability and agronomic potential, and assist in measuring and conserving biodiversity in grasslands.
| Item Type: | Article |
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| Additional Information: | FUNDING: This work was supported under the RCUK-CIAT Newton-Caldas Initiative ‘Exploiting biodiversity in Brachiaria and Panicum tropical forage grasses using genetics to improve livelihoods and sustainability’, with funding from UK’s Official Development Assistance Newton Fund awarded by UK Biotechnology and Biological Sciences Research Council (BB/R022828/1). P.T. has received further support (polyploidy and chromosome evolution) from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreements No. 844564 and No. 101006417. |
| Uncontrolled Keywords: | apomixis,brachiaria,evolution,genome-specific sequences,polyploidy,repetitive dna motifs,tropical forage grasses,medicine(all),sdg 2 - zero hunger ,/dk/atira/pure/subjectarea/asjc/2700 |
| Faculty \ School: | Faculty of Science > School of Biological Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 20 Aug 2025 16:30 |
| Last Modified: | 25 Aug 2025 00:29 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/100189 |
| DOI: | 10.1093/aob/mcab147 |
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