Identification of Major Loci and Candidate Genes for Anthocyanin Biosynthesis in Broccoli Using QTL-Seq

Abstract

Anthcyanins determine the colors of flowers, fruits, and purple vegetables and act as important health-promoting antioxidants. BT 126 represents a broccoli variety with a high content of anthocyanins (5.72 mg/g FW). Through QTL-seq bulk segregant analysis, the present study aimed to determine the quantitative trait loci (QTLs) involved in anthocyanin biosynthesis in the F2 population (n = 302), which was obtained by crossing BT 126 with a non-anthocyanin-containing SN 60. The whole-genome resequencing of purple (n = 30) and green (n = 30) bulk segregates detected ~1,117,709 single nucleotide polymorphisms (SNPs) in the B. oleracea genome. Two QTLs, tightly correlated with anthocyanin biosynthesis (p < 0.05), were detected on chromosomes 7 (BoPur7.1) and 9 (BoPur9.1). The subsequent high-resolution mapping of BoPur9.1 in the F2 population (n = 280) and F3 population (n = 580), with high-throughput genotyping of SNPs technology, narrowed the major anthocyanin biosynthesis QTL region to a physical distance of 73 kb, containing 14 genes. Among these genes, Bo9g174880, Bo9g174890, and Bo9g174900 showed high homology with AT5G07990 (gene encoding flavonoid 3′ hydroxylase), which was identified as a candidate gene for BoPur9.1. The expression of BoF3’H in BT 126 was significantly higher than that in SN60. Multiple biomarkers, related to these QTLs, represented potential targets of marker-assisted selection (MAS) foranthocyanin biosynthesis in broccoli. The present study provided genetic insights into the development of novel crop varieties with augmented health-promoting features and improved appearance.