A novel quantitative trait locus on chromosome A9 controlling oleic acid content in Brassica napus

Abstract

Summary One of the most important goals in the breeding of oilseed crops, including Brassica napus, is to improve the quality of edible vegetable oil, which is mainly determined by the seed fatty acid composition, particularly the C18:1 content. Previous studies have indicated that the C18:1 content is a polygenic trait, and no stable quantitative trait loci (QTLs) except for FAD2 have been reported. By performing a GWAS using 375 low erucic acid B. napus accessions genotyped with the Brassica 60K SNP array and constructing a high‐density SNP‐based genetic map of a 150 DH population, we identified a novel QTL on the A9 chromosome. The novel locus could explain 11.25%, 5.72% and 6.29% of phenotypic variation during three consecutive seasons and increased the C18:1 content by approximately 3%–5%. By fine mapping and gene expression analysis, we found three potential candidate genes and verified the fatty acids in a homologous gene mutant of Arabidopsis. A metal ion‐binding protein was found to be the most likely candidate gene in the region. Thus, the C18:1 content can be further increased to about 80% with this novel locus together with FAD2 mutant allele without compromise of agronomic performance. A closely linked marker, BnA129, for this novel QTL (OLEA9) was developed so that we can effectively identify materials with high C18:1 content at an early growth stage by marker‐assisted selection. Our results may also provide new insight for understanding the complex genetic mechanism of fatty acid metabolism.

Identification of QTLs Containing Resistance Genes for Sclerotinia Stem Rot in Brassica napus Using Comparative Transcriptomic Studies

“…The relative cycle threshold (Ct) value was used to measure relative expression by the 2 − Ct method. BnaA09g14410D (PP2A-1) gene was used as control to normalize the expression data (Zhao et al, 2019). The detail of genes and primers are listed in Supplementary Table S4.…”

Development and screening of EMS mutants with altered seed oil content or fatty acid composition in Brassica napus

“…It is estimated that an increase of oil content by 1% equals an increase of the seed yield by 2-3% (Wang et al, 2004). Fatty acid composition is the main factor that determines the nutritional quality of vegetable oils for human health, and breeding high oleic acid oil with reasonable levels of other fatty acids is one of the major goals of rapeseed breeding (Zhao et al, 2019). Thus, understanding of the mechanism of oil biosynthesis is of great importance for the improvement of seed oil content and fatty acid composition of rapeseed.…”

Heterogeneous Distribution of Erucic Acid in Brassica napus Seeds

“…Like most oilseeds, triacylglycerols (TAGs) comprise 95% of B. napus seed oil which are composed of a glycerol backbone esterified with three fatty acyl chains (Ai et al, 2014;Guan et al, 2016). These fatty acids vary in levels of saturation and carbon lengths and can contain mono/polyunsaturated fatty acids such as oleic (C18:1), linoleic (C18:2), linolenic (C18:3) and erucic (C22:1) acids, and/or saturated fatty acids such as palmitic acid (C16:0) and stearic acid (C18:0) (Zhao et al, 2007;Lu et al, 2016;Zhao et al, 2019).…”

“…There are two major seed-oil types of B. napus, low-erucic acid type and high-erucic acid type. Low erucic acid content (< 2%) is a major evaluation index for edible rapeseed cultivars (Hristov et al, 2011;Yan et al, 2015), and reducing erucic acid content has been a major goal for rapeseed breeding programs (Yan et al, 2015;Zhao et al, 2019). Alternatively, cultivars of B. napus containing high erucic acid are an important resource for industrial applications (Hristov et al, 2011).…”