Search

Chinese kale is a characteristic vegetable crop originating from China and being suggested to be a possible ancestor of various cultivated B. oleracea vegetables. It has both white and yellow petals and is therefore a desirable plant for use in research on petal color formation. In our study, the Chinese kale landrace YCK-1 (yellow petals) was crossed with the Chinese kale inbred line Lb07M (white petals) to construct mapping populations for genetic analysis and fine mapping of the petal color gene. The results indicated that yellow petal color is controlled by a single recessive gene named ckpc, which was preliminarily located in a 2.06-Mb candidate region of chromosome C03 using whole-genome resequencing combined with bulked segregant analysis (BSA). Fine mapping with traditional molecular marker technology was used to narrow down the ckpc gene in a 69.0-kb interval flanked by the markers M916 and SNP4 at genetic distances of 0.07 cM and 0.04 cM, respectively. Gene annotation revealed 5 genes in that region, and Bo3g158650 was annotated as a carotenoid cleavage dioxygenase 4 (CCD4) gene, which is known to function in flower and flesh color formation. Sequence analysis revealed that the Bo3g158650 gene in the white-petaled parent, Lb07M, had an identical sequence to that in the ‘TO1000’ reference genome, while a 7.61-kb CACTA-like transposable element 1 (TE1) insertion was found in this gene in the yellow-petaled parent, YCK-1. These results increase the understanding of the mechanism underlying petal color formation in Brassica.