Abstract
Spikelet number is an important target trait for wheat yield improvement. Thus, the identification and verification of novel quantitative trait locus (QTL)/genes controlling spikelet number are essential for dissecting the underlying molecular mechanisms and hence for improving grain yield. In the present study, we constructed a high-density genetic map for the Kechengmai1/Chuanmai42 doubled haploid (DH) population using 13,068 single-nucleotide polymorphism (SNP) markers from the Wheat 55K SNP array. A comparison between the genetic and physical maps indicated high consistence of the marker orders. Based on this genetic map, a total of 27 QTLs associated with total spikelet number per spike (TSN) and fertile spikelet number per spike (FSN) were detected on chromosomes 1B, 1D, 2B, 2D, 3D, 4A, 4D, 5A, 5B, 5D, 6A, 6B, and 7D in five environments. Among them, five QTLs on chromosome 2D, 3D, 5A, and 7D were detected in multiple environments and combined QTL analysis, explaining the phenotypic variance ranging from 3.64% to 23.28%. Particularly, QTsn/Fsn.cib-3D for TSN and FSN [phenotypic variation explained (PVE) = 5.97–23.28%, limit of detection (LOD) = 3.73–18.51] is probably a novel locus and located in a 4.5-cM interval on chromosome arm 3DL flanking by the markers AX-110914105 and AX-109429351. This QTL was further validated in other two populations with different genetic backgrounds using the closely linked Kompetitive Allele-Specific PCR (KASP) marker KASP_AX-110914105. The results indicated that QTsn/Fsn.cib-3D significantly increased the TSN (5.56–7.96%) and FSN (5.13–9.35%), which were significantly correlated with grain number per spike (GNS). We also preliminary analyzed the candidate genes within this locus by sequence similarity, spatial expression patterns, and collinearity analysis. These results provide solid foundation for future fine mapping and cloning of QTsn/Fsn.cib-3D. The developed and validated KASP markers could be utilized in molecular breeding aiming to increase the grain yield in wheat.
Highlights
Bread wheat (Triticum aestivum L.) is one of the most important stable foods in the world, providing more than 20% of the calories and protein in our daily diet (Yao et al, 2019; Liu et al, 2020)
No significant correlation was detected between total spikelet number per spike (TSN) and thousand kernel weight (TKW), TSN and plant height (PH), TSN and spike length (SL), fertile spikelet number per spike (FSN) and TKW, FSN and PH, and FSN and SL were observed in the K1 × CM42 (K1/CM42) population
Grain number per spike as one of three major components determining wheat yield is determined by the number of FSN and fertile floret per spikelet
Summary
Bread wheat (Triticum aestivum L.) is one of the most important stable foods in the world, providing more than 20% of the calories and protein in our daily diet (Yao et al, 2019; Liu et al, 2020). Grain yield of wheat is a complex trait affected by a multitude of genetic and environmental factors and is usually constituted of three major components, i.e., thousand kernel weight (TKW), grain number per spike (GNS), and spike number per unit area (Wang et al, 2018; Kuzay et al, 2019). The number of fertile spikelet number per spike (FSN) and fertile floret per spikelet determined GNS (Guo et al, 2017; Golan et al, 2019). Previous studies have showed that floret fertility is severely affected by environmental and genetic factors as an abortion process of floral structures existing continuously during the whole floral developmental process (Guo and Schnurbusch, 2015; Sakuma et al, 2019). Understanding the genetic factors underlying spikelet number would provide the prerequisite information necessary to improve wheat yield
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