Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, Hunan, 410004, People's Republic of China.
National Innovation Alliance of Wintersweet, Henan Academy of Forestry, Zhengzhou, Henan, 450008, People's Republic of China.
Plant J. 2021 Dec;108(6):1662-1678. doi: 10.1111/tpj.15533. Epub 2021 Oct 23.
Wintersweet (Chimonanthus praecox) is one of the most important ornamental plants. Its color is mainly determined by the middle tepals. However, the molecular mechanisms underlying the intriguing flower color development among different wintersweet groups are still largely unknown. In addition, wintersweet belongs to magnoliids, and the phylogenetic position of magnoliids remains to be determined conclusively. Here, the whole genome of red flower wintersweet, a new wintersweet type, was sequenced and assembled with high quality. The genome comprised 11 super-scaffolds (chromosomes) with a total size of 737.03 Mb. Based on the analyses of the long branch attraction, incomplete lineage sorting, sparse taxon sampling, and other factors, we suggest that a bifurcating tree may not fully represent the complex early diversification of the angiosperms and that magnoliids are most likely sister to the eudicots. The wintersweet genome appears to have undergone two whole-genome duplication (WGD) events: a recent WGD event representing an independent event specific to the Calycanthaceae and an ancient WGD event shared by Laurales. By integrating genomic, transcriptomic, and metabolomic data, CpANS1 and the transcription factor CpMYB1 were found to play key roles in regulating tepal color development, whereas CpMYB1 needs to form a complex with bHLH and WD40 to fully perform its regulatory function. The present study not only provides novel insights into the evolution of magnoliids and the molecular mechanism for flower color development, but also lays the foundation for subsequent functional genomics study and molecular breeding of wintersweet.
腊梅（Chimonanthus praecox）是最重要的观赏植物之一。其颜色主要由中部花被片决定。然而，不同腊梅群体中迷人的花色发育的分子机制在很大程度上仍然未知。此外，腊梅属于木兰类植物，木兰类植物的系统发育位置仍有待最终确定。在此，我们对红花腊梅（一个新的腊梅品种）的全基因组进行了测序和高质量组装。基因组由 11 个超级支架（染色体）组成，总大小为 737.03 Mb。基于长枝吸引、不完全谱系分选、稀疏分类群采样等因素的分析，我们认为二分树可能无法充分代表被子植物早期的复杂多样化，而木兰类植物最有可能与真双子叶植物互为姐妹群。腊梅基因组似乎经历了两次全基因组复制（WGD）事件：最近的一次 WGD 事件代表了蜡梅科特有的独立事件，而古老的 WGD 事件则是 Laurales 共有的。通过整合基因组、转录组和代谢组数据，我们发现 CpANS1 和转录因子 CpMYB1 在调控花被片颜色发育方面发挥着关键作用，而 CpMYB1 需要与 bHLH 和 WD40 形成复合物才能充分发挥其调节功能。本研究不仅为木兰类植物的进化和花色发育的分子机制提供了新的见解，也为后续的腊梅功能基因组学研究和分子育种奠定了基础。
