Comparative Mapping of Glucosinolate Accumulation in Brassica A, B, C Genomes

Glucosinolates are sulfur-rich secondary metabolites found in the Brasicaceae, which are well-known for their effects on human health as a cancer-preventive substance, and plant resistance to insects and pathogens. However, it is still less known about the genetic basis and regulation of the biosynthesis in Brassica rapa species. In our study, we identified the quantitative trait loci (QTL) for seed glucosinolate compound in Brassica rapa and compared map alignment between B.rapa. B. napus, B. juncea and Arabidopsis thaliana to identify candidate genes. The QTL identification for glucosinolate accumulation in B.rapa seed was carried out by using CRF₃ population, derived from a cross between Chinese cabbage type “Chiifu” and rapid cycling type “RCBr” which showed significant difference in glucosinolate content. Ten different glucosinolate compounds were detected in parents and segregate quantitatively in CRF₃ population. 1Twenty four loci controlling each ten and total glucosinolate compound were identified, with one major locus in chromosome A08. Further, through synteny genomic comparision to A.thaliana, candidate genes and single nucleotide polymorphisms (SNPs) between prental lines were identified from whole genome re-sequenced data, a few of which were validated by mapping to QTL regions. The candidate genes involved in glucosinolate biosynthesis pathway will be useful for B.rapa breeding program.