Selection for Greater -Glucan Content in Oat Grain

terol (Davidson et al., 1991; Klopfenstein and Hoseney, 1987). Oat (Avena sativa L.) -glucan lowers serum cholesterol in hu-Glucan is a cell wall polysaccharide found in seeds mans. Development of oat cultivars with greater groat (caryopsis) -glucan content would increase the nutritional and economic value of the Gramineae (Stinard and Nevins, 1980; Nevins et of the crop. The objectives of this experiment were to evaluate the al., 1978). Among cereals, oat and barley (Hordeum response to phenotypic selection among individual S0 plants for greater vulgare L.) have the greatest concentrations of -glucan groat -glucan content in two genetically broad-based populations; (Wood, 1994; Åman and Hesselman, 1985; Prentice et to compare selected experimental lines to standard check cultivars; al., 1980), but oat generally has a larger proportion of and to estimate genetic variances and heritabilities and to test for soluble -glucan (Lee et al., 1997). In oat and barley nonadditive genetic variance for -glucan content. We measured groat grains, -glucan is found mainly in the endosperm and -glucan contents of check cultivars and parental lines and random the subaleurone layer (Wood, 1993; Wood et al., 1983). S0:1 lines from initial and selected generations of each population Lim et al. (1992) reported that the groat -glucan congrown in field experiments in 1996 and 1997 at two Iowa locations. tent ranged from 38 to 61 g kg 1 among 102 oat lines, Mean -glucan content increased from 53.9 to 59.9 g kg 1 in one population, and from 63.5 to 66.0 g kg 1 in the other, following selecincluding commercial cultivars, experimental lines, and tion. Genetic variance of -glucan content decreased by 9 to 22% accessions of the wild, interfertile oat relative A. sterfollowing selection, but heritability for -glucan content did not ilis L. change significantly. Heritability estimates ranged from 0.80 to 0.85 Oat -glucan content is a polygenic trait under the on a line mean basis. Additive variance was the only substantial control of genes with mainly additive effects (Holthaus component of genetic variance. Some experimental lines had signifiet al., 1996; Kibite and Edney, 1998). Heritability esticantly greater -glucan content than the best check cultivars and mates for -glucan content have ranged from 0.27 to lines. Phenotypic selection for greater groat -glucan content will be 0.58 (Holthaus et al., 1996; Humphreys and Mather, effective for developing cultivars with elevated -glucan contents. 1996; Kibite and Edney, 1998). -Glucan content is affected by environmental factors, including soil nitrogen level and precipitation (Brunner and Freed, 1994; HumS cholesterol levels are strongly related to phreys et al., 1994; Peterson, 1991; Peterson et al., 1995; coronary heart disease risk in humans (Mayes, 1990; Welch et al., 1991). Although genotype environment Shekelle et al., 1981). Greater levels of high-density interaction sometimes is a significant source of variation lipoprotein cholesterol are related to lower incidence for -glucan content, the ranking of genotypes is generof coronary heart disease, whereas greater levels of lowally consistent over environments (Peterson et al., 1995; density lipoprotein cholesterol are associated with Brunner and Freed, 1994; Lim et al., 1992; Saastamoinen greater levels of coronary heart disease (Castelli et al., et al., 1992). 1986; Stamler, 1979; Miller et al., 1977). Soluble fiber The inheritance of -glucan content and the availabilhas the potential to reduce serum cholesterol levels in ity of technology developed to measure the trait rapidly humans (Shinnick et al., 1991; Van Horn et al., 1988; by flow injection analysis (FIA) (Jørgensen, 1988) or Jenkins et al., 1975). Oat bran and oatmeal have been near infrared reflectance spectrophotometry (NIRS) intensively studied as sources of dietary fiber for human (Osborne et al., 1983) make possible the improvement diets (Sacks, 1991). Oat soluble fiber, when added to the of oat -glucan content through phenotypic selection. daily diet, tends to lower serum low-density lipoprotein The development of oat cultivars with greater groat cholesterol and total blood cholesterol, particularly in -glucan contents should increase the nutritional and individuals with initially greater levels of serum choleseconomic value of the oat crop. terol (Welch, 1995; Ripsin et al., 1992; Shinnick et al., The objectives of this study were (i) to develop two 1991; Anderson et al., 1984). This results in a reduction genetically broad-based oat populations from parents of the risk of coronary heart disease. The (1→3),(1→4)with greater levels of -glucan content and to conduct -D-glucan ( -glucan) has been identified as the active phenotypic selection for greater groat -glucan content component of soluble fiber that lowers serum cholesin these populations, (ii) to determine the progress from phenotypic selection of individual S0 plants for greater C.T. Cervantes-Martinez, Universidad Autonoma Chapingo, Carret-glucan content, and (iii) determine if selection reera Mexico-Texcoco km 38.5, Texcoco, Edo. de Mex., Mexico 56230; sulted in changes in genetic variance and heritability for K.J. Frey, Dep. of Agronomy, Iowa State Univ., Ames, IA 50011; P.J. White, Dep. of Food Science and Human Nutrition, Iowa State -glucan content, and to determine if additive variance Univ., Ames, IA 50011; D.M. Wesenberg, USDA-ARS, National is the predominant component of genetic variance for Small Grains Germplasm Research Facility, P.O. Box 307, Aberdeen, -glucan content. ID 83210; J.B. Holland, USDA-ARS Plant Science Research Unit, Dep. of Crop Science, Box 7620, North Carolina State Univ., Raleigh, NC 27695-7620. Received 25 Feb. 2000. *Corresponding author Abbreviations: BLUP, best linear unbiased predictor; FIA, flow injec([email protected]). tion analysis; NIRS, near infrared reflectance spectroscopy; PI, plant introduction; REML, restricted maximum likelihood. Published in Crop Sci. 41:1085–1091 (2001).