Efficient marker-assisted breeding for clubroot resistance in elite Pol-CMS rapeseed varieties by updating the locus.

UNLABELLED

Clubroot disease poses a severe threat to rapeseed () production worldwide and has recently been spreading across China at an unprecedented pace. Breeding and cultivation of resistant varieties constitute a promising and environment-friendly approach to mitigating this threat. In this study, the clubroot resistance locus was successfully transferred into SC4, a shared paternal line of three elite varieties in five generations by marker-assisted backcross breeding. Kompetitive allele specific PCR (KASP) markers of clubroot resistance gene and its linked high erucic acid gene () were designed and applied for foreground selection, and 1,000 single-nucleotide polymorphisms (SNPs) were selected and used for the background selection. This breeding strategy produced recombinants with the highest recovery ratio of the recurrent parent genome (> 95%) at BCF while breaking the linkage with during the selection. An updated version of the paternal line (SC4R) was generated at BCF, showing significantly improved clubroot resistance at the seedling stage via artificial inoculation, and was comparable to that of the donor parent. Field trials of the three elite varieties and their updated versions in five environments indicated similar agronomic appearance and final yield. The introduced breeding strategy precisely pyramids the and loci with the assistance of technical markers in a shorter period and could be applied to other desirable traits for directional improvement in the future.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11032-022-01305-9.