Song Xuebin, Xu Yuhui, Gao Kang, Fan Guangxun, Zhang Fan, Deng Chengyan, Dai Silan, Huang He, Xin Huaigen, Li Yingying
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of the Ministry of Education, Beijing Forestry University, School of Landscape Architecture, Beijing Forestry University, 35 East Qinghua Road, Beijing, 100083 China.
College of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao, 266109 Shandong China.
Hortic Res. 2020 Jul 1;7:108. doi: 10.1038/s41438-020-0333-1. eCollection 2020.
Flower type is an important and extremely complicated trait of chrysanthemum. The corolla tube merged degree (CTMD) and the relative number of ray florets (RNRF) are the two key factors affecting chrysanthemum flower type. However, few reports have clarified the inheritance of these two complex traits, which limits directed breeding for flower-type improvement. In this study, 305 F hybrids were obtained from two parents with obvious differences in CTMD and RNRF performance. Using specific-locus amplified fragment sequencing (SLAF-seq) technology, we constructed a high-density genetic linkage map with an average map distance of 0.76 cM. Three major QTLs controlling CTMD and four major QTLs underlying RNRF were repeatedly detected in the 2 years. Moreover, the synteny between the genetic map and other Compositae species was investigated, and weak collinearity was observed. In QTL regions with a high degree of genomic collinearity, eight annotated genes were probed in the L. and L. var. ramosa Hort. genomes. Furthermore, 20 and 11 unigenes were identified via BLAST searches between the SNP markers of the QTL regions and the and transcriptomes, respectively. These results lay a foundation for molecular marker-assisted breeding and candidate gene exploration in chrysanthemum without a reference assembly.
花型是菊花重要且极为复杂的性状。花冠管融合程度（CTMD）和舌状花相对数量（RNRF）是影响菊花花型的两个关键因素。然而，关于这两个复杂性状的遗传研究鲜有报道，这限制了针对花型改良的定向育种。本研究以CTMD和RNRF表现差异明显的两个亲本杂交获得了305个F代杂种。利用特异性位点扩增片段测序（SLAF-seq）技术，构建了平均图距为0.76 cM的高密度遗传连锁图谱。连续两年重复检测到3个控制CTMD的主效QTL和4个控制RNRF的主效QTL。此外，研究了该遗传图谱与其他菊科物种之间的共线性，发现共线性较弱。在基因组共线性程度较高的QTL区域，在野菊和毛华菊基因组中探测到8个注释基因。此外，分别通过QTL区域的SNP标记与菊花和野菊转录组之间的BLAST搜索，鉴定出20个和11个单基因。这些结果为无参考基因组组装的菊花分子标记辅助育种和候选基因挖掘奠定了基础。
