To date, more than 20 clubroot resistance (CR) loci have been reported in the A-genome of Brassica rapa; however, only a few of them has been introgressed into B. napus canola. The introgression of additional CR loci will broaden the genetic base of resistance of this crop. In this paper, we report the genetic basis of CR of B. rapa var. pekinensis cultivar ‘Bilko’ introgressed into B. napus, mapping this resistance using a recombinant inbred line (RIL) population developed from B. napus × Bilko-CR interspecific cross. Evaluation of the F₂ and F₃ populations of Bilko revealed that a single gene controls resistance to pathotype 3 in this cultivar. Quantitative trait loci-seq approach using whole-genome resequencing identified a genomic region of chromosome A03 associated with this resistance in the RIL population. Single nucleotide polymorphism (SNP)-based allele-specific markers from the TIR-NB-LRR (TNL) gene Bra012688 co-segregated with this resistance, however, with 0.4–0.8% recombination. Bra012688 is located at 23,877,250–23,883,169 bp of B. rapa cultivar Chiifu-401 whole-genome assembly v.3.0, and at 378 bp downstream of another TNL gene Bra012689. Molecular markers, linked to previously reported CR loci of A03, did not co-segregate with the resistance in the RIL population; this demonstrates the need for the development of new markers for the CR loci following introgression into the recipient species. The knowledge and the SNP allele-specific markers developed in this study could be used in breeding for clubroot resistance in B. napus.

中文翻译：

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油菜渗入甘蓝型油菜根肿病抗性图谱及抗性分子标记的开发

迄今为止，在芸苔A 基因组中已经报道了 20 多个根肿病抗性 (CR) 位点；然而，其中只有少数已渗入欧洲油菜油菜籽中。额外 CR 基因座的基因渗入将拓宽该作物的抗性遗传基础。在本文中，我们报告了B. rapa var. CR 的遗传基础。pekinensis栽培品种 'Bilko' 渗入到欧洲油菜中，使用从欧洲油菜× Bilko-CR 种间杂交开发的重组自交系 (RIL) 种群绘制了这种抗性。F ₂和 F _{3 的}评估Bilko 的种群表明，在该品种中，单个基因控制着对致病型 3 的抗性。使用全基因组重测序的定量性状基因座序列方法确定了与 RIL 群体中的这种抗性相关的染色体 A03 的基因组区域。然而，来自 TIR-NB-LRR (TNL) 基因Bra012688 的基于单核苷酸多态性 (SNP) 的等位基因特异性标记与这种抗性共分离，重组率为 0.4-0.8%。Bra012688位于油菜品种 Chiifu-401 全基因组组装 v.3.0 的 23,877,250–23,883,169 bp 处，以及另一个 TNL 基因Bra012689 的下游 378 bp. 与先前报道的 A03 CR 基因座相关联的分子标记并未与 RIL 群体中的抗性共分离；这表明在基因渗入受体物种后需要为 CR 基因座开发新标记。本研究中开发的知识和 SNP 等位基因特异性标记可用于培育欧洲油菜根肿病抗性。