Development of Kasp Markers for Restorer Homozygosity in the Ogu-Inra CMS System in Brassica napus L.

The average canola yield in Canada has grown from 20 bu/ac in 1989 to 38 bu/ac in 2015. One of the main reasons for this yield increase has been the development of Brassica napus L. hybrids. Hybrid seed tends to provide advantages compared to open pollinated varieties, including plant establishment and growth rate as well as final seed yield. For 2016, the global rapeseed production is estimated to be 65 million metric tons, from which around 80% is comprised of hybrid seed. The use of a pollination control system is essential for hybrid seed production in B. napus. The ogu–INRA CMS system is a cytological variant of the radish- (Raphanus sativus L.) derived Ogu CMS system introduced through interspecific introgression into B. napus. In this system, there are three different lines; A-lines are male-sterile, B-lines are fertile maintainer lines for the respective A-lines and R-lines (restorer) are male-fertile restorer lines. Homozygous restorer lines are required to produce fertile hybrids. Thus, a co-dominant marker associated with restoration capability is a requirement in B. napus breeding programs. Co-dominant Rfo marker development has been challenging due to the allotetraploid highly repetitive nature of the B. napus genome and the unknown sequence / precise location of the entire introgression in different genetic backgrounds. In this study, KASP (Kompetitive Allele Specific PCR) markers were developed based on SNP (Single Nucleotide Polymorphism) data generated from the Illumina Infinium 60K Brassica SNP chipSequence analysis demonstrated that the source, genetic background and introgression location impact the efficacy and accuracy of the markers. Distinct KASP primers differentiate hemizygous from homozygous R-lines based upon the Rfo source and background. The implications of these results and their use in B. napus breeding will be discussed.