Genetic mapping of QTL for maize leaf width combining RIL and IF2 populations

PLOS ONE, Nov 2019

Leaf width is an important component of plant architecture that affects light capture during photosynthesis and wind circulation under dense planting conditions. To improve understanding of the genetic mechanisms involved in leaf width at different positions, a comprehensive evaluation using the RIL (Recombinant Inbred Line) and IF2 (Immortalized F2) populations and a subsequent meta-analysis were performed. Forty-seven QTL associated with leaf width at different positions below the tassel were detected. The individual effects of QTL explained 3.5% to 17.0% of the observed phenotypic variation, and ten QTL explained over 10%. The initial QTL were integrated into eight mQTL (meta-QTL) through a meta-analysis. Our results suggested that leaf widths at different positions may be affected by several of the same mQTL and may also be regulated by many different mQTL. These results provide useful information for breeding high density tolerant inbred lines and hybrid cultivars, as well as for using marker-assisted selection for important mQTL.

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Genetic mapping of QTL for maize leaf width combining RIL and IF2 populations

December Genetic mapping of QTL for maize leaf width combining RIL and IF2 populations Ruixiang Liu 0 1 Qingchang Meng 0 1 Fei Zheng 0 1 Lingjie Kong 0 1 Jianhua Yuan 0 1 Thomas LuÈ bberstedt 1 0 Institute of Food Crops, Provincial Key Laboratory of Agrobiology, Jiangsu Academy of Agricultural Sciences , Nanjing, Jiangsu Province , China , 2 Department of Agronomy, Iowa State University , Ames, Iowa State , United States of America 1 Editor: Zhiwu Zhang , Washington State Univeristy , UNITED STATES Leaf width is an important component of plant architecture that affects light capture during photosynthesis and wind circulation under dense planting conditions. To improve understanding of the genetic mechanisms involved in leaf width at different positions, a comprehensive evaluation using the RIL (Recombinant Inbred Line) and IF2 (Immortalized F2) populations and a subsequent meta-analysis were performed. Forty-seven QTL associated with leaf width at different positions below the tassel were detected. The individual effects of QTL explained 3.5% to 17.0% of the observed phenotypic variation, and ten QTL explained over 10%. The initial QTL were integrated into eight mQTL (meta-QTL) through a metaanalysis. Our results suggested that leaf widths at different positions may be affected by several of the same mQTL and may also be regulated by many different mQTL. These results provide useful information for breeding high density tolerant inbred lines and hybrid cultivars, as well as for using marker-assisted selection for important mQTL. - Data Availability Statement: All relevant data are within the paper and there are no Supporting information files. Funding: This work was financed by the National Natural Science Foundation of China (No.3171444), Jiangsu Academy of Agricultural Science and Technology Innovation Fund (CX(13) 5003), and National Key Research and Development Program of China (2016YFD0101205). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Introduction Over the past several decades, improvements in plant architecture greatly increased maize grain yields [ 1, 2 ]. All of leaf size and shape morphological traitsplay important role in determining plant architecture. Leaf size, determinated by leaf width, leaf lengthand leaf area, is an important component of leaf morphology and significantly influences the canopy morphology, photosynthetic activity, and hence grain yield [3]. Leaf width is an important component of leaf size. Smaller and narrower leaf widths decrease shade effects on lower leaves and enhance light capture for photosynthesis in dense plantings with a high leaf area index [ 4 ]. Excessive leaf size may decrease grain yield, owing to a decrease in photosynthetically active radiation utilization [ 5 ]. Therefore, understanding the genetic mechanisms of maize leaf width at different position would not only address the radiation use efficiency in plant science but also facilitate the breeding of tolerant to high planting density maize with an optimized leaf width. Leaf development is initiated from the shoot apical meristem (SAM) [ 6 ]; then the leaf polarity is established by three main axes, named proximal-distal (longitudinal), midvein-margin (mediolateral) and adaxial-abaxial (dorsoventral); finally the leaf shape and size is determined by a coordinated regulation of cell differentiation and expansion along these axes[ 7 ]. Leaf width is determined via differentiation along the mediolateral of founder cells in the peripheral zone of the shoot apical meristem [ 4 ]. In maize, several key genes that affect the development of the axes have been identified by using mutants, such as the narrow sheath ns1 and ns2 mutants [ 8 ], the narrow and threadlike leaf phenotypes of lbl1 [ 9 ] and rgd2 [ 10 ]. These mutants have helped to elucidate the molecular mechanisms of leaf-width development in maize. In the past several decades, natural variation in maize leaf width has been determined by using quantitative trait locus (QTL) mapping [3, 4, 11±14]. For example, Guo et al. [ 4 ] have identified 46 QTL associated with the width of the four consecutive leaves above the uppermost ear in four RIL populations and in three environments. In addition, Yang et al. [ 3 ] have detected 83 QTL associated with the width of eight leaves below the tassel. A genome-wide association study (GWAS) method has been used to detect variants at candidate loci and genes responsible for leaf width. Tian et al. [ 15 ] have identified 34 QTL for leaf width through NAM-GWAS (nested association mapping population). Additionally, Yang et al. [ 16 ] have found 18 SNPs associated with ear leaf width. Current research is often focus on the leaves (one to three) near the ear, owing to their effect on grain yield; only two QTL mapping studies on leaves at different positions have been published to date [ 3, 4 ], and thes (...truncated)


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Ruixiang Liu, Qingchang Meng, Fei Zheng, Lingjie Kong, Jianhua Yuan, Thomas Lübberstedt. Genetic mapping of QTL for maize leaf width combining RIL and IF2 populations, PLOS ONE, 2017, Volume 12, Issue 12, DOI: 10.1371/journal.pone.0189441