Limited haplotype diversity underlies polygenic trait architecture across 70 years of wheat breeding

Scott, Michael F., Fradgley, Nick, Bentley, Alison R., Brabbs, Thomas, Corke, Fiona, Gardner, Keith A., Horsnell, Richard, Howell, Phil, Ladejobi, Olufunmilayo, Mackay, Ian J., Mott, Richard and Cockram, James (2021) Limited haplotype diversity underlies polygenic trait architecture across 70 years of wheat breeding. Genome Biology, 22 (1). ISSN 1474-760X

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Abstract

Background Selection has dramatically shaped genetic and phenotypic variation in bread wheat. We can assess the genomic basis of historical phenotypic changes, and the potential for future improvement, using experimental populations that attempt to undo selection through the randomizing effects of recombination. Results We bred the NIAB Diverse MAGIC multi-parent population comprising over 500 recombinant inbred lines, descended from sixteen historical UK bread wheat varieties released between 1935 and 2004. We sequence the founders’ genes and promoters by capture, and the MAGIC population by low-coverage whole-genome sequencing. We impute 1.1 M high-quality SNPs that are over 99% concordant with array genotypes. Imputation accuracy only marginally improves when including the founders’ genomes as a haplotype reference panel. Despite capturing 73% of global wheat genetic polymorphism, 83% of genes cluster into no more than three haplotypes. We phenotype 47 agronomic traits over 2 years and map 136 genome-wide significant associations, concentrated at 42 genetic loci with large and often pleiotropic effects. Around half of these overlap known quantitative trait loci. Most traits exhibit extensive polygenicity, as revealed by multi-locus shrinkage modelling. Conclusions Our results are consistent with a gene pool of low haplotypic diversity, containing few novel loci of large effect. Most past, and projected future, phenotypic changes arising from existing variation involve fine-scale shuffling of a few haplotypes to recombine dozens of polygenic alleles of small effect. Moreover, extensive pleiotropy means selection on one trait will have unintended consequences, exemplified by the negative trade-off between yield and protein content, unless selection and recombination can break unfavorable trait-trait associations.

Item Type: Article
Uncontrolled Keywords: gwas,genomic prediction,imputation,low-coverage whole-genome sequencing,magic,multi-parent population,phenomics,pleiotropy,wheat,ecology, evolution, behavior and systematics,genetics,cell biology ,/dk/atira/pure/subjectarea/asjc/1100/1105
Faculty \ School: Faculty of Science > School of Biological Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 22 May 2021 00:07
Last Modified: 16 Sep 2021 11:11
URI: https://ueaeprints.uea.ac.uk/id/eprint/80069
DOI: 10.1186/s13059-021-02354-7

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