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Tier 3 — Observational / field trialPeer-reviewed

Diverged subpopulations in tropical<i>Urochloa</i>(<i>Brachiaria</i>) forage species indicate a role for facultative apomixis and varying ploidy in their population structure and evolution

Janet Higgins, Paulina Tomaszewska, TK Pellny, Valheria Castiblanco, Jacobo Arango, Joe Tohmé, Trude Schwarzacher, R. A. C. Mitchell, J. S. Heslop‐Harrison, José J. De Vega

Annals of Botany · 2022

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Summary

This molecular genetics study examined the population structure and genetic diversity of five Urochloa species (wild-origin African accessions representing the commercial breeding gene pool) to understand how ploidy and apomictic reproduction shape evolutionary divergence. The authors identified distinct subpopulations within U. brizantha and U. humidicola that were unrelated to ploidy but consistent with ecotypic divergence, and found evidence that polyploid forms of U. decumbens and U. brizantha share a common tetraploid ancestor, indicating ploidy as a reproductive barrier. These differentiated subpopulations in apomictic polyploid U. brizantha could be utilised in hybrid breeding programmes for tropical forage development.

Regional applicability

This study focuses on African-origin tropical forage grasses used primarily in marginal soils of tropical and subtropical regions; direct applicability to United Kingdom farming is limited as Urochloa species are not widely adopted in temperate UK pasture systems. However, the genetic insights may inform breeding strategies for improved forage crops in UK farming contexts through international breeding programmes.

Key measures

1.1 million single nucleotide polymorphisms; genetic admixture analysis; principal component analysis; phylogenetic relationships; ploidy level; reproductive mode (apomictic vs. sexual)

Outcomes reported

The study identified three highly differentiated subpopulations in U. brizantha and two in U. humidicola using RNA-sequencing of 1.1 million SNP loci across 111 accessions. Subpopulation structure was found to be largely independent of ploidy level but related to apomictic reproduction and potential ecotypic divergence.

Theme
Farming systems, soils & land use
Subject
Grassland & pasture systems
Study type
Research
Study design
Genetic population study using molecular markers and phylogenetic analysis
Source type
Peer-reviewed study
Status
Published
Geography
International
System type
Pasture-based livestock
DOI
10.1093/aob/mcac115
Catalogue ID
SNmonuukyw-kbadm7

Topic tags

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