Identification of Heterosis-Associated Stable QTLs for Ear-Weight-Related Traits in an Elite Maize Hybrid Zhengdan 958 by Design III

Abstract

Heterosis plays a decisive role in maize production worldwide, but its genetic basis remains unclear. In this study, we explored heterosis for ear-weight (EW)-related traits using a North Carolina Experiment III design (Design III) population derived from the elite maize hybrid Zhengdan 958. Quantitative trait loci (QTL) analysis was conducted based on phenotypic data collected from five environments using a high-density linkage map that consisted of 905 single nucleotide polymorphisms (SNP). A total of 38 environmentally stable QTLs were detected, and the numbers for the Z1 and Z2 populations were 18 and 20, respectively. All environmentally stable QTLs for Z2 were characterized by the overdominance effect (OD), which indicated that overdominance was one of the most important contributors to the heterosis of EW-related traits. Consistent with the significant positive correlations between EW-related traits, 9 genomic regions with overlapped QTLs for different traits were found and were located on chromosomes 1 (1), 3 (2), 4 (3), 7 (1), 8 (1), and 9 (1). Compared to previous reports, we found that the genomic regions for heterosis were not always congruent between different hybrids, which suggested that the combination of heterotic loci in different hybrids was genotype-dependent. Collectively, these data provided further evidence that the potential utilization of QTLs for heterosis may be feasible by pyramiding if we treat the QTLs as inherited units.

Variation for heterodimerization and nuclear localization among known and novel oil palm SHELL alleles

“…Although the data reported here do not directly prove a heterotic mechanism, we and others have postulated that heterozygosity for SHELL variants, in combination with a wild‐type Sh DeliDura allele, represents a case of single‐gene heterosis for oil yield (Singh et al , , Jin et al , ; Li et al , ; Fievet et al , ). Models proposed to account for heterosis include dominance, overdominance, pseudodominance, epistasis and dosage models involving copy number variation or polyploidy, allelic variation, gene expression differences and/or dominant negative macromolecular interactions.…”

“…In this case, the lysine to asparagine substitution encoded by sh AVROS is predicted to disrupt DNA binding, as this highly conserved lysine residue is involved in DNA binding of MADS-box proteins in other plants (Huang et al, 1996;Immink et al, 2010). Although the data reported here do not directly prove a heterotic mechanism, we and others have postulated that heterozygosity for SHELL variants, in combination with a wildtype Sh DeliDura allele, represents a case of single-gene heterosis for oil yield (Singh et al, 2013a, Jin et al, 2017Li et al, 2017;Fievet et al, 2018). Models proposed to account for heterosis include dominance, overdominance, pseudodominance, epistasis and dosage models involving copy number variation or polyploidy, allelic variation, gene expression differences and/or dominant negative macromolecular interactions.…”

Accumulation Profiles of Embryonic Salt-Soluble Proteins in Maize Hybrids and Parental Lines Indicate Matroclinous Inheritance: A Proteomic Analysis

“…Maize hybrids are widely cultivated for production as their F 1 generation has superior qualities than those of parental generation, a phenomenon known as heterosis. Previous studies have provided insights into the mechanism of heterosis on molecular level (Jahnke et al, 2010 ; Marcon et al, 2010 , 2013 ; Fu et al, 2011 ; Guo et al, 2013 ; Hu et al, 2016 ; Li et al, 2017 ). For instance, maize hybrid embryos have been reports to have strong crossbreeding advantages at the early stage after fertilization (Wang, 1947 ; Meyer et al, 2007 ).…”

QTL mapping of three ear traits using a doubled haploid population of maize

“…Improving grain yield of crops is one of the major objectives of modern breeding efforts to meet the demand of increasing population worldwide. Although grain yield is a complex quantitative trait exhibiting low breeding efficiency (Austin & Lee, ; Yan et al., ), the yield component traits always show high heritability, and thus, they serve as the target for the genetic improvement of grain yield in maize (Huo et al., ; Li et al., ; Shi et al., ). In the present study, we have collected phenotypic data for four ear traits, EL, ED, LBT and CD, of a permanent DH population of maize (Figures , and ), and we have identified multiple QTLs responsible for three of them, EL, ED and CD, by taking advantage of a SNP‐based high‐density genetic map (Table and Figure ).…”