Biology subjects

Horsnell, R.

Publications and source records attributed to Horsnell, R..

3 recordsLinked to original sources

bioRxiv2022

A wheat chromosome segment substitution line series supports characterisation and use of progenitor genetic variation

Genome-wide introgression and substitution lines have been developed in many plant species, enhancing mapping precision, gene discovery and the identification and exploitation of variation from wild relatives. Created over multiple generations of crossing and/or backcrossing accompanied by marker-assisted selection, the resulting introgression lines are a fixed genetic resource. In this study we report the development of spring wheat chromosome segment substitution lines generated to systematically capture genetic variation from tetraploid (Triticum turgidum ssp dicoccoides) and diploid (Aegilops tauschii) progenitor species. Generated in a common genetic background over four generations of backcrossing, the material is a base resource for the mapping and characterisation of wheat progenitor variation. To facilitate further exploitation the final population was genetically characterised using a high- density genotyping array and a range of agronomic and grain traits assessed to demonstrate the the potential use of the populations for trait localisation in wheat.

genetics↗

bioRxiv2021

Evolution of the bread wheat D-subgenome and enriching it with diversity from Aegilops tauschii

Aegilops tauschii, the diploid wild progenitor of the D-subgenome of bread wheat, constitutes a reservoir of genetic diversity for improving bread wheat performance and environmental resilience. To better define and understand this diversity, we sequenced 242 Ae. tauschii accessions and compared them to the wheat D-subgenome. We characterized a rare, geographically-restricted lineage of Ae. tauschii and discovered that it contributed to the wheat D-subgenome, thereby elucidating the origin of bread wheat from at least two independent hybridizations. We then used k-mer-based association mapping to identify discrete genomic regions with candidate genes for disease and pest resistance and demonstrated their functional transfer into wheat by transgenesis and wide crossing, including the generation of a library of synthetic hexaploids incorporating diverse Ae. tauschii genomes. This pipeline permits rapid trait discovery in the diploid ancestor through to functional genetic validation in a hexaploid background amenable to breeding.

plant biology↗

bioRxiv2020

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

BackgroundBreeding has helped improve bread wheat yield significantly over the last century. Understanding the potential for future crop improvement depends on relating segregating genetic variation to agronomic traits. ResultsWe bred NIAB Diverse MAGIC population, comprising over 500 recombinant inbred lines, descended from sixteen bread wheat varieties released between 1935-2004. We sequenced the founders exomes and promotors by capture. Despite being highly representative of North-West European wheat and capturing 73% of global polymorphism, we found 89% of genes contained no more than three haplotypes. We sequenced each line with 0.3x coverage whole-genome sequencing, and imputed 1.1M high-quality SNPs that were over 99% concordant with array genotypes. Imputation accuracy remained high at coverage as low as 0.076x, with or without the use of founder genomes as reference panels. We created a genotype-phenotype map for 47 traits over two years. We found 136 genome-wide significant associations, concentrated at 42 genetic loci with large and often pleiotropic effects. Outside of these loci most traits are polygenic, as revealed by multi-locus shrinkage modelling. ConclusionsHistorically, wheat breeding has reshuffled a limited palette of haplotypes; continued improvement will require selection at dozens of loci of diminishing effect, as most of the major loci we mapped are known. Breeding to optimise one trait generates correlated trait changes, exemplified by the negative trade-off between yield and protein content, unless selection and recombination can break critical unfavourable trait-trait associations. Finally, low coverage whole genome sequencing of bread wheat populations is an economical and accurate genotyping strategy.

genomics↗