Fine scale genomic signals of admixture and alien introgression among Asian rice landraces

Santos Joao, Chebotarov Dmytro, McNally Kenneth L., Bartholome Jérôme, Droc Gaëtan, Billot Claire, Glaszmann Jean-Christophe. 2019. Fine scale genomic signals of admixture and alien introgression among Asian rice landraces. Genome Biology and Evolution, 11 (5) : 1358-1373.

Quartile : Q2, Sujet : EVOLUTIONARY BIOLOGY / Quartile : Q2, Sujet : GENETICS & HEREDITY

Résumé : Modern rice cultivars are adapted to a range of environmental conditions and human preferences. At the root of this diversity is a marked genetic structure, owing to multiple foundation events. Admixture and recurrent introgression from wild sources have played upon this base to produce the myriad adaptations existing today. Genome-wide studies bring support to this idea, but understanding the history and nature of particular genetic adaptations requires the identification of specific patterns of genetic exchange. In this study, we explore the patterns of haplotype similarity along the genomes of a subset of rice cultivars available in the 3,000 Rice Genomes data set. We begin by establishing a custom method of classification based on a combination of dimensionality reduction and kernel density estimation. Through simulations, the behavior of this classifier is studied under scenarios of varying genetic divergence, admixture, and alien introgression. Finally, the method is applied to local haplotypes along the genome of a Core set of Asian Landraces. Taking the Japonica, Indica, and cAus groups as references, we find evidence of reciprocal introgressions covering 2.6% of reference genomes on average. Structured signals of introgression among reference accessions are discussed. We extend the analysis to elucidate the genetic structure of the group circum-Basmati: we delimit regions of Japonica, cAus, and Indica origin, as well as regions outlier to these groups (13% on average). Finally, the approach used highlights regions of partial to complete loss of structure that can be attributed to selective pressures during domestication.

Mots-clés Agrovoc : Oryza sativa, génome, structure de la population, variété, Introgression, allèle, polymorphisme génétique, haplotype

Mots-clés géographiques Agrovoc : Asie

Mots-clés libres : 3,000 Rice Genomes, Oryza sativa, SNPs, Local haplotypes, Population structure, Kernel density estimation

Classification Agris : F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

Auteurs et affiliations

• Santos Joao
• Chebotarov Dmytro, IRRI [International Rice Research Institute] (PHL)
• McNally Kenneth L., IRRI [International Rice Research Institute] (PHL)
• Bartholome Jérôme, CIRAD-BIOS-UMR AGAP (FRA) ORCID: 0000-0002-0855-3828
• Droc Gaëtan, CIRAD-BIOS-UMR AGAP (FRA) ORCID: 0000-0003-1849-1269
• Billot Claire, CIRAD-BIOS-UMR AGAP (FRA)
• Glaszmann Jean-Christophe, CIRAD-BIOS-UMR AGAP (FRA) ORCID: 0000-0001-9918-875X - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/593225/)

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