Abstract
Maximum tiller number and productive tiller number are important traits for wheat grain yield, but research involving the temporal expression of tiller number at different quantitative trait loci (QTL) levels is limited. In the present study, a population set of 371 recombined inbred lines derived from a cross between Chuan-Nong18 and T1208 was used to construct a high-density genetic map using a Wheat55K SNP Array and to perform dynamic QTL analysis of the tiller number at four growth stages. A high-density genetic map containing 11,583 SNP markers and 59 SSR markers that spanned 4,513.95 cM and was distributed across 21 wheat chromosomes was constructed. A total of 28 single environmental QTL were identified in the recombined inbred lines population, and among these, seven QTL were stable and used for multi-environmental and dynamic analysis. These QTL were mapped to chromosomes 2D, 4A, 4D, 5A, 5D, and 7D, respectively. Each QTL explained 1.63–21.22% of the observed phenotypic variation, with an additive effect from -20.51 to 11.59. Dynamic analysis showed that cqTN-2D.2 can be detected at four growth stages of tillering, explaining 4.92–17.16% of the observed phenotypic variations and spanning 13.71 Mb (AX-109283238-AX-110544009: 82189047-95895626) according to the physical location of the flanking markers. The effects of the stable QTL were validated in the recombined inbred lines population, and the beneficial alleles could be utilized in future marker-assisted selection. Several candidate genes for MTN and PTN were predicted. The results provide a better understanding of the QTL selectively expressing the control of tiller number and will facilitate future map-based cloning. 9.17% SNP markers showed best hits to the Chinese Spring contigs. It was indicated that Wheat55K Array was efficient and valid to construct a high-density wheat genetic map.
Highlights
Common wheat (Triticum aestivum L.) is one of the most valuable and widely used crops in the world
In results using the average measurement of TNES, tiller number during pre-winter per unit area (TNPW), maximum tiller number per unit area (MTN), and productive tiller number (PTN) between 2 years for correlation analysis, traits were significantly positive correlated with each other in the recombined inbred lines (RILs) population (Table 1)
The mean values of TNES, TNPW, MTN, and PTN in the RIL population for the 2 years are shown in Supplementary Figure S1
Summary
Common wheat (Triticum aestivum L.) is one of the most valuable and widely used crops in the world. Sichuan Province is a typical rainfed agricultural area in Southwestern China that has very few light hours and more rainy days in winter This has resulted in a macro-type spike and low tillering-capacity winter wheat with high-density sowing in recent years, but this may change. New breeding hypotheses for wheat in Sichuan Basin and similar environments is to increase TN appropriately to construct an ideal population structure. According to this thinking, our breeding produced wheat cultivars such as CN12, CN17, and CN18 with higher tillering capacity. To increase TN in future breeding programs, it is essential to elucidate the genetic mechanism controlling TN in wheat
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