Genetic variation and genotype x environment interactions of phytosterol content in three doubled haploid populations of winter rapeseed

Phytosterols are natural constituents of vegetable oils and are known for their cholesterol-lowering properties. The oil of rapeseed (Brassica napus L.) is one of the richest natural sources of phytosterols. Genetically enhancing the phytosterol content could give an added value to the rapeseed oil and derived products. Our objectives were to develop a gas-liquid chromatographic method for the analysis of phytosterol content in seeds of oilseed rape, to determine the genetic variation and the genotype x environment interactions, and to estimate correlations between phytosterols and other important seed quality traits in three doubled haploid populations of winter rapeseed. The populations were tested during several years in three to four environments. Sitosterol and campesterol were detected as the two major phytosterols followed by brassicasterol, avenasterol, and stigmasterol. Large differences were found in total phytosterol content (2.57 to 4.15 g kg(-1) seed), with predominant genetic variance components resulting in high heritabilities ranging from 0.84 to 0.91. Phytosterol content was not negatively correlated with oil content and there were no close correlations to protein and glucosinolate content. The large genetic variation along with high heritabilities indicate that an effective breeding for enhanced phytosterol content and modified composition should be possible without negative impacts on oil, protein, or glucosinolate content.