Abstract
Wheat yield is not only affected by three components of yield, but also affected by plant height (PH). Identification and utilization of the quantitative trait loci (QTL) controlling these four traits is vitally important for breeding high-yielding wheat varieties. In this work, we conducted a QTL analysis using the recombinant inbred lines (RILs) derived from a cross between two winter wheat varieties of China, “Nongda981” (ND981) and “Nongda3097” (ND3097), exhibiting significant differences in spike number per unit area (SN), grain number per spike (GNS), thousand grain weight (TGW), and PH. A total of 11 environmentally stable QTL for these four traits were detected. Among them, four major and stable QTLs (QSn.cau-4B-1.1, QGns.cau-4B-1, QTgw.cau-4B-1.1, and QPh.cau-4B-1.2) explaining the highest phenotypic variance for SN, GNS, TGW, and PH, respectively, were mapped on the same genomic region of chromosome 4B and were considered a QTL cluster. The QTL cluster spanned a genetic distance of about 12.3 cM, corresponding to a physical distance of about 8.7 Mb. Then, the residual heterozygous line (RHL) was used for fine mapping of the QTL cluster. Finally, QSn.cau-4B-1.1, QGns.cau-4B-1, and QPh.cau-4B-1.2 were colocated to the physical interval of about 1.4 Mb containing 31 annotated high confidence genes. QTgw.cau-4B-1.1 was divided into two linked QTL with opposite effects. The elite NILs of the QTL cluster increased SN and PH by 55.71–74.82% and 14.73–23.54%, respectively, and increased GNS and TGW by 29.72–37.26% and 5.81–11.24% in two environments. Collectively, the QTL cluster for SN, GNS, TGW, and PH provides a theoretical basis for improving wheat yield, and the fine-mapping result will be beneficial for marker-assisted selection and candidate genes cloning.
Highlights
As one of the most important food crops in the world, common wheat (Triticum aestivum L.) is essential in satisfying human demand for calories and guaranteeing food security
In the work reported here, we developed a recombinant inbred lines (RILs) population derived from a cross between Nongda981 (ND981) and Nongda3097 (ND3097) to perform quantitative trait loci (QTL) analysis on three components of yield and plant height (PH), with the purpose to dissect the genetic basis of these four traits
The means and ranges of four traits (SN, grain number per spike (GNS), thousand grain weight (TGW), and PH) of RIL population and two parents across seven individual environments are shown in Supplementary Table 2
Summary
As one of the most important food crops in the world, common wheat (Triticum aestivum L.) is essential in satisfying human demand for calories and guaranteeing food security. Wheat yield is a complex quantitative trait determined by three components (Simmonds et al, 2014), and is influenced by heredity and environment. Among these three components of yield, there have been many studies on quantitative trait loci (QTL) mapping for thousand grain weight (TGW) due to phenotypic stability and high heritability (Kuchel et al, 2007). Several homologous genes that control grain size in rice have been cloned, providing better insights into the genetic basis of grain size in wheat (Nadolska-Orczyk et al, 2017), such as Grain Size 5 (TaGS5-3A) (Ma et al, 2016), Grain Weight 2 (TaGW2-A1) (Simmonds et al, 2016), Grain Length 3 (TaGL35A) (Yang et al, 2019), and Cytokinin Oxidase 6 (TaCKX6-D1) (Zhang et al, 2012)
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