Abstract
Kernel shape related traits (KSRTs) have been shown to have important influences on grain yield. The previous studies that emphasize kernel length (KL) and kernel width (KW) lack a comprehensive evaluation of characters affecting kernel shape. In this study, materials of the basic generations (B73, Mo17, and B73 × Mo17), 82 intermated B73 × Mo17 (IBM) individuals, and the corresponding triple testcross (TTC) populations were used to evaluate heterosis, investigate correlations, and characterize the quantitative trait loci (QTL) for six KSRTs: KL, KW, length to width ratio (LWR), perimeter length (PL), kernel area (KA), and circularity (CS). The results showed that the mid-parent heterosis (MPH) for most of the KSRTs was moderate. The performance of KL, KW, PL, and KA exhibited significant positive correlation with heterozygosity but their Pearson’s R values were low. Among KSRTs, the strongest significant correlation was found between PL and KA with R values was up to 0.964. In addition, KW, PL, KA, and CS were shown to be significant positive correlation with 100-kernel weight (HKW). 28 QTLs were detected for KSRTs in which nine were augmented additive, 13 were augmented dominant, and six were dominance × additive epistatic. The contribution of a single QTL to total phenotypic variation ranged from 2.1% to 32.9%. Furthermore, 19 additive × additive digenic epistatic interactions were detected for all KSRTs with the highest total R2 for KW (78.8%), and nine dominance × dominance digenic epistatic interactions detected for KL, LWR, and CS with the highest total R2 (55.3%). Among significant digenic interactions, most occurred between genomic regions not mapped with main-effect QTLs. These findings display the complexity of the genetic basis for KSRTs and enhance our understanding on heterosis of KSRTs from the quantitative genetic perspective.
Highlights
Heterosis was proposed in the early 20th century to describe the superiority of heterozygous F1 compared with its homozygous parents in one or more traits [1,2]
The complete linkage map was comprised of 77 InDels, 32 presence/absence variation (PAV), 61 single nucleotide polymorphisms (SNP), and the remaining 574 other public markers
To further explore the relationship between the heterozygosity and the kernel shape related traits (KSRTs), we investigated the correlations between the heterozygous levels of TC(B) and TC(M) individuals and their KSRTs (S3 Table)
Summary
Heterosis was proposed in the early 20th century to describe the superiority of heterozygous F1 compared with its homozygous parents in one or more traits [1,2]. Heterosis and QTLs of KSRTs been widely applied for improving crops, and it has been effective for maize production [3,4,5]. Most previous studies on maize yield related traits focused on ear related traits [18,19,20,21]. Kernel related traits have garnered more attention with studies attempting to elucidate the genetic basis of grain yield for a variety of reasons. Kernel size and weight were characterized as important determinants of grain yield [22,23] and large inbred kernels had the potential to produce better early vigor hybrids and promote flowering time [24]. Kernel shape related traits (KSRTs) such as KL and KW are likely the major characters affecting grain yield
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
