Characteristics of Color Development in Seeds of Brown- and Yellow-Seeded Heading Chinese Cabbage and Molecular Analysis of , the Candidate Gene Controlling Seed Coat Color

The proanthocyanidin (PA) is the main flavonoids which affect the seed coat color in species. In this paper, characteristics of color development and accumulation of flavonoids were analyzed in the seeds of brown-seeded (B147) and yellow-seeded (B80) heading Chinese cabbage ( L. ssp. ). It is found that the content of phenolic compounds in B147 were significantly more than that of B80 by using dimethylaminocinnamaldehyde (DMACA) staining and toluidine blue O (TBO) staining. In previous studies, the locus associated with seed coat color has been mapped. The results of whole genome re-sequencing showed that there are large fragment deletions variation in the mapping region between the brown-seeded parent '92S105' and the yellow-seeded parent '91-125.' Based on the genome annotation information, the (), is likely to be the candidate gene controlling seed coat color. A 94-base deletion was found in the 96th base downstream of the initiation codon in the of yellow seed, thus, the termination codon TGA was occurred in the 297th base which makes the full length of of yellow seed is 300 bp. Based on the differential sequences of of brown and yellow seed, a functional marker, Brsc-yettg1, was developed to detect the variation of . Quantitative real-time PCR analysis of in different tissues showed that expression levels of was not tissue-specific. During the whole seed development period, the expression of in B147 was higher than that of B80. The expression levels of four structural genes, , and in B147 were also higher than those in B80. The co-segregation molecular markers obtained in this report and related information provide a basis for further understanding of the molecular mechanism of seed coat color in heading Chinese cabbage.