Abstract
BackgroundPlant Architecture Related Traits (PATs) are of great importance for maize breeding, and mainly controlled by minor effect quantitative trait loci (QTLs). However, cloning or even fine-mapping of minor effect QTLs is very difficult in maize. Theoretically, large population and high density genetic map can be helpful for increasing QTL mapping resolution and accuracy, but such a possibility have not been actually tested.ResultsHere, we employed a genotyping-by-sequencing (GBS) strategy to construct a linkage map with 16,769 marker bins for 1021 recombinant inbred lines (RILs). Accurately mapping of well studied genes P1, pl1 and r1 underlying silk color demonstrated the map quality. After QTL analysis, a total of 51 loci were mapped for six PATs. Although all of them belong to minor effect alleles, the lengths of the QTL intervals, with a minimum and median of 1.03 and 3.40 Mb respectively, were remarkably reduced as compared with previous reports using smaller size of population or small number of markers. Several genes with known function in maize were shown to be overlapping with or close neighboring to these QTL peaks, including na1, td1, d3 for plant height, ra1 for tassel branch number, and zfl2 for tassel length. To further confirm our mapping results, a plant height QTL, qPH1a, was verified by an introgression lines (ILs).ConclusionsWe demonstrated a method for high resolution mapping of minor effect QTLs in maize, and the resulted comprehensive QTLs for PATs are valuable for maize molecular breeding in the future.
Highlights
Plant Architecture Related Traits (PATs) are of great importance for maize breeding, and mainly controlled by minor effect quantitative trait loci (QTLs)
Wang et al BMC Plant Biology (2018) 18:17 populations are leading to sampling bias, affecting the estimation of Quantitative trait locus (QTL) effect and the accuracy of QTL location [18, 19], and unfavorable linkage event in small populations would even result in misleading inferences [20]
We demonstrated a method for high resolution mapping of minor effect QTLs in maize, and the resulted comprehensive QTLs for PATs are valuable for maize molecular breeding in the future
Summary
Plant Architecture Related Traits (PATs) are of great importance for maize breeding, and mainly controlled by minor effect quantitative trait loci (QTLs). Cloning or even fine-mapping of minor effect QTLs is very difficult in maize. Plant architecture related traits (PATs) are of great importance for maize, as they are crucial indicators to the growth and development of the plant and influence the yield [1, 2]. Studies in past decades indicated that PATs are mainly affected by minor effect quantitative traits loci (QTLs), especially as reflected in the Nested Association Mapping (NAM) population [3,4,5]. Fine mapping coupled with further precise cloning of Previous QTL studies of agronomic traits in crops were mainly based on relatively small populations and a few hundred or less molecular markers. Small populations always have the drawback of limited recombination limit the mapping resolution [19]
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