Molecular Breeding Opportunities and Challenges for Complex Trait Recombination on Wheat Chromosome 4B
Knox, R.E., Bokore, F.E., Cuthbert, R.D., Berraies, S., McCallum, B.D., Henriquez, M.A., Kumar, S., Burt, A., Fetch, T., Monro, C., Bhavani, S., Piche, I., Campbell, H.L., Meyer, B., Ruan, Y., Bhadauria, V., N'diaye, A., Pozniak, C.J., A. Sharpe, A., R., and DePauw, R. 2019. Molecular Breeding Opportunities and Challenges for Complex Trait Recombination on Wheat Chromosome 4B. XXVII International Plant and Animal Genome Conference, San Diego, CA, USA, January 12-16, 2019.
A challenge in breeding is assembling desirable alleles of priority traits into a coupling configuration. Detailed marker-trait analysis of breeding germplasm provides opportunity for targeted molecular breeding with directed assembly of favourable alleles. A doubled haploid population of up to 775 lines from ‘Carberry’/’AC Cadillac’ was assessed in specialized nurseries in Canada, Kenya and New Zealand for different traits that included leaf, stem and yellow rusts, pseudo-black chaff, Fusarium head blight (FHB), height, maturity and shattering. The lines of the population were genotyped using the 90K Infinium iSelect assay and quantitative trait locus (QTL) analysis was performed. A complex genomic region associated with leaf and stem rust resistance, reduced plant height (rht1), maturity, shattering and FHB resistance was identified on chromosome 4B. Favourable alleles for reduced height, leaf and stem rust and shattering resistance were contributed by Carberry. Early maturity, pseudo-black chaff and improved resistance to FHB were contributed by AC Cadillac. A locus for yellow rust resistance and a second locus for leaf rust resistance, both from Carberry, flanked the complex locus. To take advantage of the FHB resistance, for example, will require more detailed mapping to determine if the resistance is linked to or pleiotropic with other favourable traits such as reduced height.