Genetic and QTL analysis of pericarp thickness and ear architecture traits of Korean waxy corn germplasm

Abstract

Pericarp thickness and ear traits are important selection criteria for breeding fresh market waxy corn. This research was conducted to better understand genetic control of these traits in popular South Korean germplasm now grown in Illinois. Pericarp thickness on five kernel regions, and ten inflorescence architecture traits were measured on ears from 264 F 2:3 families from a cross between Korean inbreds BH20 and BH30. All five pericarp thickness traits showed high heritabilities and were highly correlated. Multivariate principal components analysis (PCA) revealed that just one principal component (PC) explained most of the total phenotypic variation. A number of univariate quantitative trait loci (QTL) were detected and most were associated with more than one kernel pericarp region. Four out of seven PC-QTL were located in chromosome positions where three or more pericarp thickness univariate QTL were detected. Conversely, three PC-QTL were found in regions with just a single or two univariate QTL, indicating that these QTL regions may be more important for overall pericarp thickness than suggested by univariate analysis. The PCA, QTL, and PC-QTL results indicate that pericarp thickness on different kernel regions may be controlled by common genes with pleiotropic effects. Additive effects of QTL for thinner pericarp thickness came from both BH20 and BH30. For ear architecture traits, heritability varied from 0.38 to 0.72, and several traits were correlated. The PCA reduced these traits into three independent PCs, and all substantial component traits for these PCs were also significantly correlated. A number of univariate QTL were clustered closely, and some PC-QTL were detected in these regions. Some PC-QTL were found in chromosome regions where univariate QTL were not detected, again suggesting that these regions may have larger overall effects on ear architecture than suggested by univariate analyses. Collectively, these QTL may be useful for marker assisted introgression into germplasm more adapted to the U.S.

Identification of QTL for maize grain yield and kernel-related traits

“…Bin 2.03 region also may play an essential role in maize diversification. Choe and Rocheford (2012) found that QTLs for kernel number per row and kernel weight were located at this region. Cai et al (2014) reported that a QTL at bin 2.03 had a large effect on kernel row number in a B73/Mo17 F 2:3 population.…”

Identification of QTL for ear row number and two-ranked versus many-ranked ear in maize across four environments

“…For decades, with the rapid development of molecular genetic marker technology and quantitative genetics, diverse maize populations have been used to detect QTLs for ERN, which contribute to maize diversification, such as F 2 (Yu et al 2014), F 2:3 (Cai et al 2014;Choe and Rocheford 2012;Karen Sabadin et al 2008;Lu et al 2011;Veldboom and Lee 1994;Yan et al 2006), F 2:4 (Beavis et al 1994), BC 1 S 1 (Upadyayula et al 2006), BC 2 F 2 (Li et al 2007, BC 3 F 2:3 , BC 5 F 2:3 (Tian et al 2014), IF 2 (Tang et al 2010), CSSLs (Li et al 2014a) and RILs (Austin and Lee 1996;Guo et al 2008;Liu et al 2010). To date, few consistent QTL having large effects on ERN have been detected across diverse populations or environments.…”

Genotypic diversity of bran weight of whole grain rice and its relationship with grain physical traits

“…There is no report on genetic regulation of pericarp and aleurone layers in rice. However, it was demonstrated that the thickness of pericarp and aleurone layers were controlled genetically in maize, barley and sorghum (Choe & Rocheford, 2012;Dykes & Rooney, 2006;Jestin et al, 2008;Shen et al, 2003). Multiple quantitative trait loci (QTL) associated with pericarp thickness of maize kernels were identified (Choe & Rocheford, 2012;Ito & Brewbaker, 1991).…”

“…However, it was demonstrated that the thickness of pericarp and aleurone layers were controlled genetically in maize, barley and sorghum (Choe & Rocheford, 2012;Dykes & Rooney, 2006;Jestin et al, 2008;Shen et al, 2003). Multiple quantitative trait loci (QTL) associated with pericarp thickness of maize kernels were identified (Choe & Rocheford, 2012;Ito & Brewbaker, 1991). Morphological changes associated with the pericarp thickness, as reported by Ito and Brewbaker (1991), included number of cell layers, thickening of the pericarp cells and thickening of the individual pericarp cell walls.…”