Abstract: High-performance liquid chromatography（HPLC），coupled with photodiode array
detection and carotenoid standards was used to analyze caotenoid composition in different genotypes of
Chinese cabbage. A F2 population constructed by homozygous breeding lines white inner leaf cabbage
‘A21445’and orange inner leaf cabbage‘A21530’was used for markers screening and fine mapping. The
candidate or gene was screened and cloned according to Brassica rapa genome annotation information. An
internal marker in the gene was developed and verified candidate gene in F2 population. Mapping of SSR
and InDel markers on 269 individuals of F2 population，the or gene was located to a 1.4 cM interval with
the physical distance of 98.904 kb on chromosome A09 of the B. rapa genome. HPLC analysis indicated
that orange inner leaf of Chinese cabbage is due to the accumulation of prolycopene（7Z，9Z，7′Z，9′Z-tetra-cis-lycopene），9-cis-β-carotene，proneurosporene（7,9,9′-tri-cis-neurosporene）and other carotenoids
pigments. According to B. rapa genome annotation information，a candidate gene Bra031539，designated
CRTISO，was predicted within the mapped or locus. A deletion of 6 bp and 53 SNPs were found in coding
sequence of the orange type，corresponding to two glutamic acids（Glu）deletion and 12 amino acids
mutations. The functional marker was cosegregated with or loucs in F2 individuals.

Key words: Chinese cabbage, orange inner leaf, carotenoids, mapping, or candidate gene, CRTISO