Genome-Wide Association Studies of Morphological Related Traits in Chinese Cabbage (B. rapa)

Genome-wide association mapping studies are playing significant role to detect QTLs in crop germplasm, especially Brassica rapa is an important Brassica crop with large genetic and morphological diversity among its several subspecies.  Here we show the results of genome-wide association study of 145 accessions of heading type Chinese cabbage that were phenotyped for 26 traits and genotyped 1,746,802 SNPs. Traits that are plant height, head color, leaf length, head forming leaf overlap and petiole width traits were showed good association peaks in this analysis. The several previously analyzed QTLs were tightly linked with GWAS results. Plant height associated traits loci’s were identified with known genes such as DWARF gene. NAC biding transcription factor was related for leaf length, WRKY and F-box genes for head diameter. This study provides the fundamental resource for Chinese cabbage as well as other brassica genetics research and breeding, and establishes that an approach integrating next-generation genome sequencing and GWAS can be a powerful complementary strategy to study a complex traits in B. rapa.