Genetic Variation and Association Analysis of Phenolic Compounds in Rapeseed (Brassica napus L.) Mutant Lines Using Genotyping-by-Sequencing (GBS)

Abstract

The concentration of phenolic compounds in rapeseed is important because they are either anti-nutritional compounds or directly related to antioxidant activity. In this study, single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing (GBS), and an association study was conducted to investigate phenolic content in 95 rapeseed mutant lines derived from gamma rays and their original cultivar. A total of 3,196,318 SNPs were detected, resulting in the identification of a set of 70,208 union SNPs used to perform association studies. Seven compounds were identified, sinapine being the major phenolic compound (91.2–99.2%) in all genotypes. An association study was conducted for seven compounds and total phenolic content (TPC). It identified 241 SNPs that were significantly associated with these compounds, total sinapine content (TSC), and TPC. Based on the SNP markers detected, BnaC02g20420D was associated with dihexose, BnaC08g30570D with progoitrin, BnaA01g06890D with methyl sinapate, BnaA09g16810D with sinapine(4-O-8′)guaiacyl, BnaCnng39930D with trans-sinapine 1, BnaA07g31720D with trans-sinapine 2, BnaC03g31950D with sinapoyl malate, and BnaAnng27700D with TPC. These were selected as candidate genes that may play a key role in rapeseed. The SNP markers associated with these key phenolic compounds can be used as targets in breeding programs to reduce anti-nutritional components.