Background and Aims Oilseed rape (Brassica napus) is one of the most important oil crops worldwide. Phosphorus (P) deficiency severely decreases the plant height and branch number of B. napus. However, the genetic bases controlling plant height and branch number in B. napus under P deficiency remain largely unknown. This study aims to mine candidate genes for plant height and branch number by genome-wide association study (GWAS) and determine low-P-tolerance haplotypes. Methods An association panel of B. napus was grown in the field with a low P supply (P, 0 kg ha−1) and a sufficient P supply (P, 40 kg ha−1) across 2 years and plant height and branch number were investigated. More than five million single-nucleotide polymorphisms (SNPs) were used to conduct GWAS of plant height and branch number at two contrasting P supplies. Key Results A total of 2127 SNPs were strongly associated (P < 6·25 × 10−07) with plant height and branch number at two P supplies. There was significant correlation between phenotypic variation and the number of favourable alleles of associated loci on chromosomes A10 (chrA10_821671) and C08 (chrC08_27999846), which will contribute to breeding improvement by aggregating these SNPs. BnaA10g09290D and BnaC08g26640D were identified to be associated with chrA10_821671 and chrC08_27999846, respectively. Candidate gene association analysis and haplotype analysis showed that the inbred lines carrying ATT at BnaA10g09290Hap1 and AAT at BnaC08g26640Hap1 had greater plant height than lines carrying other haplotype alleles at low P supply. Conclusion Our results demonstrate the power of GWAS in identifying genes of interest in B. napus and provided insights into the genetic basis of plant height and branch number at low P supply in B. napus. Candidate genes and favourable haplotypes may facilitate marker-based breeding efforts aimed at improving P use efficiency in B. napus.

中文翻译：

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全基因组关联研究剖析了甘蓝型油菜低磷胁迫下株高和分枝数的遗传控制

背景和目标油菜（Brassica napus）是世界上最重要的油料作物之一。磷（P）缺乏严重降低了欧洲油菜的株高和分枝数。然而，在缺磷条件下控制欧洲油菜株高和分枝数的遗传基础仍然很大程度上未知。本研究旨在通过全基因组关联研究 (GWAS) 挖掘植物高度和分枝数的候选基因，并确定低 P 耐受性单倍型。方法 在 2 年内 P 供应量低（P，0 kg ha-1）和 P 供应量充足（P，40 kg ha-1）、株高和分枝数的田间种植欧洲油菜关联面板进行了调查。超过 500 万个单核苷酸多态性 (SNP) 用于在两种不同的 P 供应下进行植物高度和分枝数的 GWAS。关键结果 共有 2127 个 SNP 与两个 P 供应的植物高度和分枝数密切相关（P < 6·25 × 10-07）。表型变异与染色体 A10 (chrA10_821671) 和 C08 (chrC08_27999846) 上相关基因座的有利等位基因数量之间存在显着相关性，这将有助于通过聚合这些 SNP 来改善育种。BnaA10g09290D 和 BnaC08g26640D 被确定为分别与 chrA10_821671 和 chrC08_27999846 相关。候选基因关联分析和单倍型分析表明，在低磷供应条件下，携带 BnaA10g09290Hap1 ATT 和 BnaC08g26640Hap1 携带 AAT 的自交系比携带其他单倍型等位基因的系具有更高的株高。结论 我们的结果证明了 GWAS 在鉴定 B 中感兴趣的基因方面的能力。油菜，并提供了对欧洲油菜低磷供应下株高和分枝数的遗传基础的见解。候选基因和有利的单倍型可以促进旨在提高欧洲油菜磷利用效率的基于标记的育种工作。