Abstract
BackgroundUtilization of heterosis in maize could be critical in maize breeding for boosting grain yield. However, the genetic architecture of heterosis is not fully understood. To dissect the genetic basis of yield-related traits and heterosis in maize, 301 recombinant inbred lines derived from 08 to 641 × YE478 and 298 hybrids from the immortalized F2 (IF2) population were used to map quantitative trait loci (QTLs) for nine yield-related traits and mid-parent heterosis.ResultsWe observed 156 QTLs, 28 pairs of loci with epistatic interaction, and 10 significant QTL × environment interactions in the inbred and hybrid mapping populations. The high heterosis in F1 and IF2 populations for kernel weight per ear (KWPE), ear weight per ear (EWPE), and kernel number per row (KNPR) matched the high percentages of QTLs (over 50%) for those traits exhibiting overdominance, whereas a notable predominance of loci with dominance effects (more than 70%) was observed for traits that show low heterosis such as cob weight per ear (CWPE), rate of kernel production (RKP), ear length (EL), ear diameter (ED), cob diameter, and row number (RN). The environmentally stable QTL qRKP3–2 was identified across two mapping populations, while qKWPE9, affecting the trait mean and the mid-parent heterosis (MPH) level, explained over 18% of phenotypic variations. Nine QTLs, qEWPE9–1, qEWPE10–1, qCWPE6, qEL8, qED2–2, qRN10–1, qKWPE9, qKWPE10–1, and qRKP4–3, accounted for over 10% of phenotypic variation. In addition, QTL mapping identified 95 QTLs that were gathered together and integrated into 33 QTL clusters on 10 chromosomes.ConclusionsThe results revealed that (1) the inheritance of yield-related traits and MPH in the heterotic pattern improved Reid (PA) × Tem-tropic I (PB) is trait-dependent; (2) a large proportion of loci showed dominance effects, whereas overdominance also contributed to MPH for KNPR, EWPE, and KWPE; (3) marker-assisted selection for markers at genomic regions 1.09–1.11, 2.04, 3.08–3.09, and 10.04–10.05 contributed to hybrid performance per se and heterosis and were repeatedly reported in previous studies using different heterotic patterns is recommended.
Highlights
Utilization of heterosis in maize could be critical in maize breeding for boosting grain yield
The main objectives of this research were (1) to detect and estimate Quantitative trait loci (QTL) with additive and additive-additive effects on yield-related traits using an Recombinant inbred lines (RIL) population (2) to identify QTLs with additive, dominant, and/or epistatic effect on yield-related traits using a hybrid population derived from the RIL population (IF2 population) (3) to identify QTLs for mid-parent heterosis (MPH) using both mapping populations and (4) to identify the most suitable genomic regions associated with grain yield and MPH to be managed by marker-assisted selection
The means of the F1 were significantly higher than the means of any of the parental lines for ear weight per ear (EWPE), cob weight (CWPE), ear length (EL), ear diameter (ED), kernel weight per ear (KWPE), kernel number per row (KNPR), and rate of kernel production (RKP)
Summary
Utilization of heterosis in maize could be critical in maize breeding for boosting grain yield. Extensive research has been focused on the TSPT × Reid heterotic pattern because it is one of the predominant heterotic patterns in northern China and has been used for the production of elite hybrids such as Zhengdan958 [18]. This heterotic pattern is rarely used in southwestern China, where alternative, scarcely investigated, heterotic patterns such as PB × PA are more suitable [17]. The current study investigated the genetics of heterosis for yield-related traits in a PB × PA hybrid and the genetics of the yield-related traits per se
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