Abstract
As an important component, 1,000 kernel weight (TKW) plays a significant role in the formation of yield traits of wheat. Kernel size is significantly positively correlated to TKW. Although numerous loci for kernel size in wheat have been reported, our knowledge on loci for kernel area (KA) and kernel circumference (KC) remains limited. In the present study, a recombinant inbred lines (RIL) population containing 371 lines genotyped using the Wheat55K SNP array was used to map quantitative trait loci (QTLs) controlling the KA and KC in multiple environments. A total of 54 and 44 QTLs were mapped by using the biparental population or multienvironment trial module of the inclusive composite interval mapping method, respectively. Twenty-two QTLs were considered major QTLs. BLAST analysis showed that major and stable QTLs QKc.sau-6A.1 (23.12–31.64 cM on 6A) for KC and QKa.sau-6A.2 (66.00–66.57 cM on 6A) for KA were likely novel QTLs, which explained 22.25 and 20.34% of the phenotypic variation on average in the 3 year experiments, respectively. Two Kompetitive allele-specific PCR (KASP) markers, KASP-AX-109894590 and KASP-AX-109380327, were developed and tightly linked to QKc.sau-6A.1 and QKa.sau-6A.2, respectively, and the genetic effects of the different genotypes in the RIL population were successfully confirmed. Furthermore, in the interval where QKa.sau-6A.2 was located on Chinese Spring and T. Turgidum ssp. dicoccoides reference genomes, only 11 genes were found. In addition, digenic epistatic QTLs also showed a significant influence on KC and KA. Altogether, the results revealed the genetic basis of KA and KC and will be useful for the marker-assisted selection of lines with different kernel sizes, laying the foundation for the fine mapping and cloning of the gene(s) underlying the stable QTLs detected in this study.
Highlights
Common wheat (Triticum aestivum L.) is one of the most important food crops in the world and provides ∼20% of the protein and calories in the human diet (Chaves et al, 2013)
A 371 recombinant inbred lines (RIL) population developed by the cross Chuannong18 (CN18) and T1208 was used for QTL analyses based on a high-density genetic linkage map constructed by the Wheat55K SNP array (Hu et al, 2017; Ren et al, 2018, 2021)
The TKW is positively correlated with the wheat yield and is significantly affected by the kernel size
Summary
Common wheat (Triticum aestivum L.) is one of the most important food crops in the world and provides ∼20% of the protein and calories in the human diet (Chaves et al, 2013). Due to the decrease in arable land area, population growth, and many other factors, it has been difficult for grain production to meet human demand. It is very important to increase the yield of common wheat to relieve the pressure on grain and meet social demand. The 1,000 kernel weight (TKW) and kernel number per spike (KN) have important effects on the wheat yield, and they are usually considered key factors of yield formation. In the long history of wheat breeding and domestication, the kernel size has been a major selection and breeding objective and has been widely used for selection to improve wheat yield (Gegas et al, 2010). The genetic improvement of kernel size is beneficial to increase the TKW and increase the yield of common wheat
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