Heterotic loci identified for maize kernel traits in two chromosome segment substitution line test populations

Yafei Wang,Xiangge Zhang,Canran Sun,Zhanyong Guo,Huiling Xie,Xiaoyi Wei,Runmiao Tian,Jihua Tang,Xia Shi,Jiao Jin

doi:10.1038/s41598-018-29338-1

Abstract

Heterosis has been widely used to increase grain quality and yield, but its genetic mechanism remains unclear. In this study, the genetic basis of heterosis for four maize kernel traits was examined in two test populations constructed using a set of 184 chromosome segment substitution lines (CSSLs) and two inbred lines (Zheng58 and Xun9058) in two environments. 63 and 57 different heterotic loci (HL) were identified for four kernel traits in the CSSLs × Zheng58 and CSSLs × Xun9058 populations, respectively. Of these, nine HL and six HL were identified for four kernel traits in the CSSLs × Zheng58 and CSSLs × Xun9058 populations, at the two locations simultaneously. Comparative analysis of the HL for the four kernel traits identified only 21 HL in the two test populations simultaneously. These results showed that most HL for the four kernel traits differed between the two test populations. The common HL were important loci from the Reid × Tangsipingtou heterotic model, and could be used to predict hybrid performance in maize breeding.

Highlights

Heterosis is used to describe the superiority of heterozygous genotypes over parental homozygotes with respect to one or more characteristics[1]
We dissected the genetic basis of heterosis for four kernel traits using two test populations constructed from a chromosome segment substitution lines (CSSLs) population and two test inbred lines, Zheng[58] and Xun9058
Because parental lines of maize commercial hybrids belong to different heterotic groups, the heterotic loci (HL) involved in different hybrids are always diverse. hQTL and HL mapping research has usually been carried out with biparental populations such as F2:3, DH, and recombinant inbred lines (RILs) test populations[13,18,38,39,40], immortalised F2 (IF2) populations[2,16], and CSSLs or SSSLs test populations[23,37,41,42]

Summary

Introduction

Heterosis is used to describe the superiority of heterozygous genotypes over parental homozygotes with respect to one or more characteristics[1]. The first population design, which is based on the North Carolina Design III (NCIII), uses F2, F3, or recombinant inbred lines (RILs) that are backcrossed with their parental lines Such a design was once used to identify QTLs with overdominant or dominant effects[13,19,20]. In the genetic basis of kernel weight and its related traits, several QTL mapping studies have been conducted for maize[21,32,33,34], and the QTL for secondary traits of kernel weight, including kernel length, width, depth or thickness, volume, and ratio have been identified in previous studies[35,36]. These HL associated with kernel traits and their associated molecular markers may be used to predict hybrid performance in future maize breeding experiments

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