|Holland, Jim - Jim|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2001
Publication Date: 6/1/2001
Interpretive Summary: B-glucan is the "active ingredient" in oatmeal that lowers cholesterol in humans. Therefore, development of oat varieties with higher levels of b-glucan in the grain would improve the nutritional value of the crop and may enhance the economic value of the grain for U.S. oat growers. We showed in a previous experiment that selection for individual plants with greater b-glucan contents resulted in significant increases in this trait. Based on this, we suggested that developing cultivars with elevated b-glucan contents would be feasible. To develop such cultivars, however, the elevated b-glucan trait must be combined with agronomically acceptable grain yields, test weights, and grain oil and protein contents. The purpose of this study was to determine the effect of selecting for greater b-glucan content on these other traits. We found that selection for greater b-glucan content resulted in reduced grain yield and test weight, reduced oil content, and increased protein content. Our results suggest that lines with elevated b-glucan contents tend to have improved nutritional quality from the elevate b-glucan itself combined with increased protein content and lower oil (fat) contents. However, the decreases in yield and test weight that accompanied increases in b-glucan content suggest that developing elevated b-glucan content oat cultivars with good yields will be challenging. We suggest a method to combine selection for both yield and b-glucan content.
Technical Abstract: Oat (Avena sativa L.) b-glucan lowers serum cholesterol in humans. Thus, enhancing its content in oat cultivars for human consumption is desirable. Phenotypic selection for greater b-glucan content was effective in two broad-based oat populations, BG1 and BG2. The initial and selected cycles of each of these populations were evaluated in 1996 and 1997 at two Iowa locations to determine the correlated responses of agronomic and grain quality traits to selection for greater b-glucan content. Mean grain yield, biomass, and test weight were reduced by 25, 23, and 2%, respectively, in one population and not affected in the other. Mean protein content increased by 5% in one population while mean oil content and heading date did not change. Plant height decreased by 5% in one population only. Correlated responses were generally favorable in terms of human nutritional value of oat grain, but unfavorable for agronomic performance. Genotypic variances were unchanged by selection, except the genetic variance for plant height in BG2 increased. Selection strengthened negative genetic correlations between b-glucan content and grain yield, biomass, and oil content in both populations, and between b-glucan content and test weight, heading date, and height in one population. b-glucan yield (the product of b-glucan content and grain yield), was positively genetically correlated with both grain yield (r=0.92 in both populations) and b-glucan content (r = 0.66 and r = 0.26 in the two populations). Selection for greater b-glucan yield could be used to improve b-glucan content and grain yield simultaneously.