Identification of QTLs Associated with Oil Content in a High-Oil <i>Brassica napus</i> Cultivar and Construction of a High-Density Consensus Map for QTLs Comparison in <i>B. napus</i>

Increasing seed oil content is one of the most important goals in breeding of rapeseed (B. napus L.). To dissect the genetic basis of oil content in B. napus, a large and new double haploid (DH) population containing 348 lines was obtained from a cross between ‘KenC-8’ and ‘N53-2’, two varieties with >10% difference in seed oil content, and this population was named the KN DH population. A genetic linkage map consisting of 403 markers was constructed, which covered a total length of 1783.9 cM with an average marker interval of 4.4 cM. The KN DH population was phenotyped in eight natural environments and subjected to quantitative trait loci (QTL) analysis for oil content. A total of 63 identified QTLs explaining 2.64–17.88% of the phenotypic variation were identified, and these QTLs were further integrated into 24 consensus QTLs located on 11 chromosomes using meta-analysis. A high-density consensus map with 1335 marker loci was constructed by combining the KN DH map with seven other published maps based on the common markers. Of the 24 consensus QTLs in the KN DH population, 14 were new QTLs including five new QTLs in A genome and nine in C genome. The analysis revealed that a larger population with significant differences in oil content gave a higher power detecting new QTLs for oil content, and the construction of the consensus map provided a new clue for comparing the QTLs detected in different populations. These findings enriched our knowledge of QTLs for oil content and should be a potential in marker-assisted breeding of B. napus.提高种子含油量是甘蓝型油菜（Brassica napus L.，以下简称B. napus L.）育种的关键目标之一。为解析甘蓝型油菜含油量的遗传基础，本研究以种子含油量差异超10%的两个品种‘KenC-8’与‘N53-2’为亲本杂交，获得了包含348个株系的大型新型双单倍体（double haploid，DH）群体，并将该群体命名为KN DH群体。研究人员构建了一张包含403个标记的遗传连锁图谱，总覆盖长度达1783.9厘摩（cM），标记平均间距为4.4 cM。对KN DH群体在8种自然环境下开展表型鉴定，并进行了含油量相关的数量性状位点（quantitative trait loci，QTL）分析。共鉴定出63个可解释2.64%~17.88%表型变异的QTL；通过元分析（meta-analysis）将这些QTL整合至11条染色体上的24个一致性QTL中。结合KN DH图谱与另外7张已发表的共享标记图谱，研究人员构建了一张包含1335个标记位点的高密度一致性图谱。在KN DH群体的24个一致性QTL中，有14个为新发现的QTL，其中A基因组包含5个新QTL，C基因组包含9个新QTL。分析结果表明，采用含油量差异显著的大型群体可提升含油量相关新QTL的检测效力；而一致性图谱的构建为不同群体间检测到的QTL比对提供了新的研究思路。上述研究结果丰富了学界对油菜含油量相关QTL的认知，可为甘蓝型油菜的标记辅助育种（marker-assisted breeding）提供潜在参考依据。