Genotype and Environment Affect Phytosterol Content and Composition of Wheat

Phytosterols (PS) lower low density lipoprotein (LDL) levels by as much as 10-14% in normal and hypercholesteromic people. High LDL levels in the blood are associated with an increased risk of coronary heart disease. Wheat germ and bran contain significant amounts of PS. The main objective of this study was to evaluate the effect of genotype and environment on PS content and composition in whole wheat grain. Protein and ash contents and mineral composition of the samples were also determined. Grain samples were collected from three cultivars, Jagger, Trego, and Intrada, grown at three locations, Alva, Balko, and Goodwell, OK in 2005. Irrigated and dryland samples were obtained from Goodwell. Total PS content and composition in the grain samples were determined using a gas chromatography system. Whole wheat grain samples varied in PS content from 202 mg/kg to 355 mg/kg. β-Sitosterol, campesterol, and stigmasterol were the major PS compounds found in all the samples. PS exhibited a significant location-by-cultivar random effect (P < 0.048), indicating the presence of genotype-by-location interaction. Within each location, a significant cultivar effect was also observed. Protein and ash contents and mineral composition of the samples, except those collected from Goodwell-dryland, were within the range published in the literature for other wheat cultivars. A fundamental understanding of compositional variation in wheat grain requires multi-environment testing of genotypes, perhaps over several years. This study is a first step for achieving this goal.