Siliques are a major carbohydrate source of energy for later seed development in rapeseed (Brassica napus). Thus, silique length has received great attention from breeders. We previously detected a novel quantitative trait locus cqSL-C7 that controls silique length in B. napus. Here, we further validated the cqSL-C7 locus and isolated its causal gene (BnaC7.ROT3) by map-based cloning. In ‘Zhongshuang11’ (parent line with long siliques), BnaC7.ROT3 encodes the potential cytochrome P450 monooxygenase CYP90C1, whereas in ‘G120’ (parent line with short siliques), a single nucleotide deletion in the fifth exon of BnaC7.ROT3 results in a loss-of-function truncated protein. Sub-cellular localization and expression pattern analysis revealed that BnaC7.ROT3 is a membrane-localized protein mainly expressed in leaves, flowers and siliques. Cytological observations showed that the cells in silique walls of BnaC7.ROT3-transformed positive plants were longer than those of transgene-negative plants in the background of ‘G120’, suggesting that BnaC7.ROT3 affects cell elongation. Haplotype analysis demonstrated that most alleles of BnaC7.ROT3 are favorable in B. napus germplasms, and its homologs may also be involved in silique length regulation. Our findings provide novel insights into the regulatory mechanisms of natural silique length variations and valuable genetic resources for the improvement of silique length in rapeseed.

中文翻译：

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BnaC7.ROT3，cqSL-C7 的因果基因，通过影响欧洲油菜细胞伸长来介导角果长度

长角果是油菜（欧洲油菜）后期种子发育的主要碳水化合物能量来源。因此，长角果的长度受到了育种者的极大关注。我们之前检测到一个新的数量性状基因座 cqSL-C7，它控制欧洲油菜中的角果长度。在这里，我们进一步验证了 cqSL-C7 基因座并通过基于图谱的克隆分离了其因果基因（BnaC7.ROT3）。在'Zhongshuang11'（具有长角果的亲本）中，BnaC7.ROT3 编码潜在的细胞色素 P450 单加氧酶 CYP90C1，而在'G120'（具有短角果的亲本）中，BnaC7.ROT3 第五个外显子中的单核苷酸缺失导致一种功能丧失的截短蛋白。亚细胞定位和表达模式分析表明，BnaC7.ROT3是一种膜定位蛋白，主要在叶、花和长角果中表达。细胞学观察显示，在'G120'背景下，BnaC7.ROT3转化阳性植株长角果壁细胞比转基因阴性植株长，提示BnaC7.ROT3影响细胞伸长。单倍型分析表明，BnaC7.ROT3的大多数等位基因在欧洲油菜种质中是有利的，其同源物也可能参与长角果长度调控。我们的研究结果为天然角果长度变异的调控机制和有价值的遗传资源提供了新的见解，以改善油菜的角果长度。单倍型分析表明，BnaC7.ROT3的大多数等位基因在欧洲油菜种质中是有利的，其同源物也可能参与长角果长度调控。我们的研究结果为天然角果长度变异的调控机制和有价值的遗传资源提供了新的见解，以改善油菜的角果长度。单倍型分析表明，BnaC7.ROT3的大多数等位基因在欧洲油菜种质中是有利的，其同源物也可能参与长角果长度调控。我们的研究结果为天然角果长度变异的调控机制和有价值的遗传资源提供了新的见解，以改善油菜的角果长度。