Activity 2: Accessing Quantitative Traits from Exotic Germplasm to Support Pre-breeding

• Utilize CRISPR-Cas9 genome-editing technologies to domesticate exotic genetic resources prior to hybrid development. We propose to design and evaluate methods to identify genetic resources with high general combining ability (GCA) by combining the methods outlined above: gene editing and hybrid wheat. We propose to efficiently recreate adaptive traits in unadapted germplasm using the CRISPR-Cas9 technology, with the achnol 2020, 38, 1274–1279.im of “adapting” this germplasm for field evaluation in F₁ hybrids of elite × exotic crosses. Adaptation traits, important for wheat in Canada and elsewhere, and their corresponding genes to be edited are listed as follows:

Genome editing targets for de novo domestication

Trait	Phenotype	Gene	Allele	Sequence variation	Reference
Reduced plant height	Short vs. tall	Rht-B1	Rht-B1b (Rht1)	SNP	Peng et al 1999 1
Photoperiod response	Insensitive vs. sensitive - Flowering time	Ppd-A1	GS100, GS105	1.1 kb deletion	Wilhelm et al 2009 2
Vernalization response	Insensitive vs. sensitive - Flowering time	VRN2	Loss of function	SNPs and deletions	Yan et al 2004 3
Grain threshability	Naked vs. hulled grains – Free-threshing	Q (WAP2)	Q	I329V amino acid substitution	Simons et al 2006 4

¹ Peng, J., et al., 'Green revolution' genes encode mutant gibberellin response modulators. Nature, 1999. 400: 256-61.
² Wilhelm, E.P., A.S. Turner, and D.A. Laurie, Photoperiod insensitive Ppd-A1a mutations in tetraploid wheat (Triticum durum Desf.). Theor Appl Genet, 2009. 118: 285-94.
³ Yan, L., et al., The Wheat VRN2 gene is a flowering repressor down-regulated by vernalization. Science, 2004. 303: 1640-4.
⁴ Simons, K.J., et al., Molecular characterization of the major wheat domestication gene Q. Genetics, 2006. 172: 547-55.





Schematic illustration of the multiplex gene editing construct to be used for creating TetraOM and the strategy for its use in generation of “adapted” exotic germplasm


• Transforming wild emmer wheat using GRF-GIF chimeras that enhance regeneration efficiency

Developing a strategy to predict combining ability based on genome-wide genotypic data that will better inform the selection of the tetraploid and diploid parents for SHW crosses and of the subsequent elite parents for backcrossing.

Strategy of accessing D genome variaon

Description of synthetic hexaploid wheat-derived germplasm