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QTL (quantitative trait loci) mapping for nitrogen use efficiency (NUE) based on a high–density consensus map of wheat

Liu, Hang (2022) QTL (quantitative trait loci) mapping for nitrogen use efficiency (NUE) based on a high–density consensus map of wheat. PhD thesis, Murdoch University.

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Nitrogen is not only an essential element for wheat growth, but also a major determinant for wheat yield and protein quality. Nitrogen use efficiency (NUE) is therefore a key factor in determining profit in wheat production, either through enhancing grain yields (GY) and grain protein content (GPC) or reducing fertilizer costs. NUE is defined as GY*GPC/N supply so both GY and GPC are targeted. To date, QTL mapping on NUE related traits has been using recombined inbred lines (RIL) and double haploid (DH) populations grown at different nitrogen levels. As most of the QTL mapping has been based on a single mapping population with limited genetic background, genetic regions identified are less abundant and of lower effects, whereas consensus maps generated from multiple genetic populations with wider genetic coverage are more efficient in QTL mapping. The Murdoch University wheat research group has developed six DH populations and using 90K SNP array analysis, a high–density consensus map was constructed containing 11,643 markers. Combined with two–year field trials, six major QTL clusters for NUE and related traits were detected on six chromosomes, explaining 4.7 – 20.8% of the phenotypic variances across environments. Two major QTL clusters (CI–2D and CI–4D) showed favourable relationships between GY and GPC, suggesting it is feasible to improve the grain yield and NUE simultaneously. A total of 176 potential candidate genes were associated with these six major QTL clusters. The use of consensus mapping based on six genetic populations varying in NUE is unprecedented, allowing identification and validation of candidate genes, target alleles and gene–based SNP haplotypes in the QTL clusters which can be used to accelerate the improvement of NUE in wheat breeding programs.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): Agricultural Sciences
Australia-China Joint Centre for Wheat Improvement
United Nations SDGs: Goal 12: Responsible Consumption and Production
Supervisor(s): Ma, Wujun, Zhang, Jingjuan and Islam, Shahidul
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