Identifying and transferring genetic diversity from the wild to improve wheat
Citation
Cloutier, S., Ravichandran, S., Edwards, T., McCallum, B., Henriquez, M.A., Humphreys, G., Cao, W., Fedak, G., Pozniak, C., You, F.M. 2018. Identifying and transferring genetic diversity from the wild to improve wheat. 9th Canadian Workshop on FHB & 4th Canadian Wheat Symposium, November 19–22, 2018 Winnipeg, Manitoba.
Abstract
Bread wheat is a polyploid crop that arose from ancient natural hybridizations. Subsequent selection,
domestication and breeding have resulted in today’s adapted elite varieties. However, these events have
also narrowed the genetic diversity of modern wheat. Broader genetic diversity exists in the wild; for
example, roughly half of the ~75 leaf rust genes identified to date came from such germplasm. Today, the
challenging identification of beneficial genetic diversity from the wild and its transfer are facilitated by
genomics. One of the most efficient transfer methods is the use of synthetic hexaploid wheat (SHW)
created by crossing Triticum turgidum (AB) to Aegilops tauschii (D), thereby re-creating the original
hybridization that produced bread wheat (ABD), but using more diverse AB and D genome donors.
Exome sequencing is a genomic technique that captures the DNA sequence of most of the protein-coding
genes. To uncover the genetic diversity of the progenitor gene pools, exome sequencing was performed
on a collection of T. turgidum, Ae. tauschii, their SHW-derived lines, and Canadian elite bread wheat
varieties. More than 3 billion 100-bp sequencing reads were aligned to the exome design reference
sequence. Sequences encoding disease resistance, photoperiod sensitivity, vernalization and grain
quality genes were extracted to determine allelic diversity for these important traits. Comparisons with the
elite germplasm revealed the novel and potentially valuable genetic diversity from the progenitor species.
Our results also illustrate the promise for SHWs as shuttle germplasm for wheat improvement and the
power of genomics-assisted pre-breeding.