Development of Heterotic Gene Pools in Brassica napus L.

Development of Heterotic Gene Pools in Brassica napus L.

Alexander Peter Cattini, Robert W. Duncan

The near doubling of Brassica napus yield from 1693 kg/ha in 1986 to 2688 bushels/acre in 2013 is due in no small part to the development of hybrids exhibiting high heterosis. Distinct inbred lines as parents should produce agronomically superior offspring, but this requires the identification of heterotic gene pools from which to draw the parents. The University of Manitoba has a diverse collection of Brassica species that has not been characterized (genotypically or phenotypically) into heterotic gene pools. In 2013, 303 B. napus accessions were evaluated for phenotypic characteristics (flower morphology, plant height, pod size and shape, growth habit, lodging resistance, time to flowering, time to maturity and seed quality) and then clustered into groups based on these phenotypic traits. These same genotypes will be characterized using genotyping by sequencing for shared presence/absence variation and single nucleotide polymorphisms, and then clustered into a second set of heterotic pools based upon this genotypic data. The genotypic and phenotypic heterotic pools will be compared and potentially combined. The genotypes from the phenotypic and genotypic pools will be also used as pollen parents in hybrids with a single male-sterile female (which was also evaluated genotypically and phenotypically). The position of the genotypes in the heterotic gene pools will be confirmed and adjusted by evaluating the agronomic performance of the hybrids in replicated yield trials in 2013 and 2014. This information will aid in the creation of favorable hybrid crosses through evaluation of inbred lines for parent potential as well as identifying the threshold level of diversity required to see a heterotic increase in agronomic and quality performance.