Identification of Candidate Genes Regulating the Seed Coat Color Trait in Sesame (Sesamum indicum L.) Using an Integrated Approach of QTL Mapping and Transcriptome Analysis

Chun Li; Yinghui Duan; Hongmei Miao; Ming Ju; Libin Wei; Haiyang Zhang

doi:10.3389/fgene.2021.700469

Identification of Candidate Genes Regulating the Seed Coat Color Trait in Sesame (Sesamum indicum L.) Using an Integrated Approach of QTL Mapping and Transcriptome Analysis

Front Genet. 2021 Aug 4:12:700469. doi: 10.3389/fgene.2021.700469. eCollection 2021.

Authors

Chun Li^{1

2}, Yinghui Duan^{1

2}, Hongmei Miao^{1

2}, Ming Ju^{1

2}, Libin Wei¹, Haiyang Zhang^{1

2}

Affiliations

¹ Henan Sesame Research Center, Henan Academy of Agricultural Sciences, Zhengzhou, China.
² Henan Key Laboratory of Specific Oilseed Crops Genomics, Henan Sesame Research Center, Henan Academy of Agricultural Sciences, Zhengzhou, China.

Abstract

Seed coat color is an important seed quality trait in sesame. However, the genetic mechanism of seed coat color variation remains elusive in sesame. We conducted a QTL mapping of the seed coat color trait in sesame using an F₂ mapping population. With the aid of the newly constructed superdense genetic linkage map comprised of 22,375 bins distributed in 13 linkage groups (LGs), 17 QTLs of the three indices (i.e., L, a, and b values) of seed coat color were detected in seven intervals on four LGs, with a phenotype variance explanation rate of 4.46-41.53%. A new QTL qSCa6.1 on LG 6 and a QTL hotspot containing at least four QTLs on LG 9 were further identified. Variants screening of the target intervals showed that there were 84 genes which possessed the variants that were high-impact and co-segregating with the seed coat color trait. Meanwhile, we performed the transcriptome comparison of the developing seeds of a white- and a black-seeded variety, and found that the differentially expressed genes were significantly enriched in 37 pathways, including three pigment biosynthesis related pathways. Integration of variants screening and transcriptome comparison results suggested that 28 candidate genes probably participated in the regulation of the seed coat color in sesame; of which, 10 genes had been proved or suggested to be involved in pigments biosynthesis or accumulation during seed formation. The findings gave the basis for the mechanism of seed coat color regulation in sesame, and exhibited the effects of the integrated approach of genome resequencing and transcriptome analysis on the genetics analysis of the complex traits.

Keywords: RNA-Seq; genetic linkage map; genome re-sequencing; seed coat color; sesame.