Marker-assisted Selection for Improved Emergence and Eating Quality in Sweet Corn

Abstract

Marker-assisted selection is proposed to be more effective than phenotypic selection in improving complex traits with low heritability. This study was designed to test empirically the efficiency of marker-assisted selection (MAS) vs. phenotypic selection (PS) in enhancing economically important characters in sweet corn using composite populations consisting of selected F2:3 families from two populations. In previous studies in our laboratory, these segregating populations were developed and assayed for genes influencing sweet corn emergence and eating quality. The 214 F2:3 families in the first population (W678su1 × IL731ase1) were classified into three sub-populations according to segregation for the se1gene. Marker-assisted selection and phenotypic selection were applied on the two homozygous sugary1 and sugary enhancer1 sub-populations separately. The second population consisted of 117 F2:3 families from the cross of Ia453sh2 × IL451bsh2. The genotypic selection was based on the polymorphism of five RFLP markers linked to QTL associated with significant effects on emergence and eating quality in the F2:3 generation. Twenty percent of the families in each population with the highest and lowest genotypic scores and phenotypic performance values were selected to constitute the MAS and PS composites, respectively. Emergence was evaluated in four different environments in Illinois and Wisconsin, while eating quality traits were evaluated in Illinois only. Results for emergence, with relatively high h2, in two out of three populations indicated that marker-assisted selection was superior to phenotypic selection. The effectiveness of MAS on enhancing stand establishment and eating quality will be discussed.