A candidate branching-controlling gene for qDBA09 was identified after delimiting a Brassica napus recessive locus within a 270-kb interval on chromosome A09. Although branching is an important trait associated with the adaptation and yield potential of rapeseed (Brassica napus), the genetic mechanisms underlining branching in this crop remain poorly understood. In this study, we characterized a naturally occurring rapeseed mutant, db1, which showed an ultrahigh branching density phenotype. By combining bulked segregant analysis (BSA) and the Brassica 60K SNP BeadChip Array, we identified two major quantitative trait loci (QTLs), qDBA09 and qDBC06, which were subsequently confirmed using the traditional QTL-mapping approach. Analysis of 208 individuals from a BC1F3 population indicated that the qDBA09 locus is a single Mendelian factor and that the dense branching phenotype is controlled by a single recessive gene. Furthermore, QTL analysis confirmed that qDBA09 explained between 9.5 and 70.5% of the variation in branching-related traits. Using 7785 individuals from the BC1F3 population, we mapped qDBA09 to a DNA fragment of approximately 270 kb in length that contained 27 predicted genes, three of which were identified as potentially involved in the control of the dense branching trait. Based on the reported function of these genes, together with sequence comparisons and co-segregation analysis, we identified a potential candidate gene for the qDBA09 locus. The present findings lay the foundations for further in-depth research on the branching mechanisms of B. napus.

中文翻译：

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油菜中控制分支的主要基因座的鉴定和精细定位。

qDBA09 的候选分支控制基因在 A09 染色体上 270-kb 间隔内划定一个欧洲油菜隐性基因座后被鉴定。尽管分枝是与油菜 (Brassica napus) 的适应性和产量潜力相关的重要性状，但对这种作物分枝的遗传机制仍然知之甚少。在这项研究中，我们表征了一种天然存在的油菜籽突变体 db1，它表现出超高的分枝密度表型。通过结合批量分离分析 (BSA) 和 Brassica 60K SNP BeadChip Array，我们确定了两个主要的数量性状基因座 (QTL)，qDBA09 和 qDBC06，随后使用传统的 QTL 作图方法进行了确认。对来自 BC1F3 群体的 208 名个体的分析表明，qDBA09 基因座是单个孟德尔因子，并且密集分支表型由单个隐性基因控制。此外，QTL 分析证实 qDBA09 解释了分支相关性状变异的 9.5% 到 70.5%。使用来自 BC1F3 群体的 7785 个个体，我们将 qDBA09 映射到长度约为 270 kb 的 DNA 片段，其中包含 27 个预测基因，其中三个被确定为可能参与控制密集分支性状。基于这些基因的报告功能，以及序列比较和共分离分析，我们确定了 qDBA09 基因座的潜在候选基因。本研究结果为进一步深入研究欧洲油菜的分枝机制奠定了基础。