AUTHOR=Ren Yanjing , He Qiong , Ma Xiaomin , Zhang Lugang 

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

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01410

DOI=10.3389/fpls.2017.01410

ISSN=1664-462X

ABSTRACT=<p>The proanthocyanidin (PA) is the main flavonoids which affect the seed coat color in <italic>Brassica</italic> 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 (<italic>Brassica rapa</italic> L. ssp. <italic>Pekinensis</italic>). 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 <italic>B. rapa</italic> genome annotation information, the <italic>TRANSPARENT TESTA GLABRA 1</italic> (<italic>TTG1</italic>), 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 <italic>TTG1</italic> of yellow seed, thus, the termination codon TGA was occurred in the 297th base which makes the full length of <italic>TTG1</italic> of yellow seed is 300 bp. Based on the differential sequences of <italic>TTG1</italic> of brown and yellow seed, a functional marker, Brsc-yettg1, was developed to detect the variation of <italic>TTG1</italic>. Quantitative real-time PCR analysis of <italic>BrTTG1</italic> in different tissues showed that expression levels of <italic>BrTTG1</italic> was not tissue-specific. During the whole seed development period, the expression of <italic>BrTTG1</italic> in B147 was higher than that of B80. The expression levels of four structural genes, <italic>BrDFR, BrANS, BrANR1</italic>, and <italic>BrANR2</italic> in B147 were also higher than those in B80. The co-segregation molecular markers obtained in this report and <italic>TTG1</italic> related information provide a basis for further understanding of the molecular mechanism of seed coat color in heading Chinese cabbage.</p>