Wu Jing, Cheng Fangyun, Cai Changfu, Zhong Yuan, Jie Xiao
National Flower Engineering Research Centre, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation and Molecular Breeding, College of Landscape Architecture, Beijing Forestry University, Beijing, China.
Mol Genet Genomics. 2017 Feb;292(1):187-200. doi: 10.1007/s00438-016-1266-0. Epub 2016 Nov 2.
Tree peony (Paeonia Sect. Moutan) is an economically important ornamental plant, but little is known about the genetic architecture of important ornamental traits. To effectively improve ornamental value, we require a better understanding of genetic architecture in the complex traits of the tree peony. Association mapping is a powerful tool for detection of variation associated with traits. Thus, we examined the genetic diversity and the population structure of 462 unrelated cultivated P. rockii individuals, then performed association mapping to identify simple sequence repeat (SSR) markers associated with 12 floral traits. We observed a moderate level of genetic diversity (PIC = 0.459) and low linkage disequilibrium (LD) between markers, demonstrating that the potential value of an LD approach in elucidating the molecular basis of the quantitative variation in this species. An analysis of population structure revealed three subgroups in the association population. Subsequent single-marker association analysis identified 46 significant associations, involving the 11 traits with 37 SSRs. These loci explained a small proportion of the phenotypic variance, ranging from 2.68 to 23.97% (mean 5.50%). We also validated 15 of the 46 associations in a linkage mapping population of 159 individuals. Finally, five associations were further confirmed in the linkage mapping population, involving the four traits with four SSRs. These results can serve as a foundation for further analyses of the genetic architecture of floral traits, and the SSRs associated in this work have potential applications in marker-assisted breeding in tree peony.
牡丹（芍药属牡丹组）是一种具有重要经济价值的观赏植物，但对于其重要观赏性状的遗传结构却知之甚少。为了有效提高观赏价值，我们需要更好地了解牡丹复杂性状的遗传结构。关联作图是检测与性状相关变异的有力工具。因此，我们研究了462个无亲缘关系的栽培紫斑牡丹个体的遗传多样性和群体结构，然后进行关联作图以鉴定与12个花部性状相关的简单序列重复（SSR）标记。我们观察到中等水平的遗传多样性（PIC = 0.459）以及标记间较低的连锁不平衡（LD），这表明LD方法在阐明该物种数量变异分子基础方面具有潜在价值。群体结构分析揭示了关联群体中的三个亚群。随后的单标记关联分析鉴定出46个显著关联，涉及11个性状和37个SSR。这些位点解释了一小部分表型变异，范围从2.68%到23.97%（平均5.50%）。我们还在一个由159个个体组成的连锁作图群体中验证了46个关联中的15个。最后，在连锁作图群体中进一步确认了5个关联，涉及4个性状和4个SSR。这些结果可为进一步分析花部性状的遗传结构奠定基础，并且本研究中关联的SSR在牡丹的标记辅助育种中具有潜在应用价值。
