Many species of the genus Kalanchoe are important horticultural plants. They have evolved the Crassulacean acid metabolism (CAM) photosynthetic pathway to allow them to be better adapted to dry environments. Despite their importance, it is still debating whether Kalanchoe is monophyletic, and understanding the past diversification of this genus requires a tremendous amount of effort and work being devoted to the studies of morphological and molecular characters of this genus. However, molecular information, plastic sequence data, in particular, reported on Kalanchoe species is scarce, and this has posed a great challenge in trying to interpret the evolutionary history of this genus. In this study, plastomes of the five Kalanchoe species, including Kalanchoe daigremontiana, Kalanchoe delagoensis, Kalanchoe fedtschenkoi, Kalanchoe longiflora, and Kalanchoe pinnata, were sequenced and analyzed. The results indicate that the five plastomes are comparable in size, guanine-cytosine (GC) contents and the number of genes, which also demonstrate an insignificant difference in comparison with other species from the family Crassulaceae. About 224 simple sequence repeats (SSRs) and 144 long repeats were identified in the five plastomes, and most of these are distributed in the inverted repeat regions. In addition, highly divergent regions containing either single nucleotide polymorphism (SNP) or insertion or deletion (InDel) mutations are discovered, which could be potentially used for establishing phylogenetic relationships among members of the Kalanchoe genus in future studies. Furthermore, phylogenetic analyses suggest that Bryophyllum should be placed into one single genus as Kalanchoe. Further genomic analyses also reveal that several genes are undergone positive selection. Among them, 11 genes are involved in important cellular processes, such as cell survival, electron transfer, and may have played indispensable roles in the adaptive evolution of Kalanchoe to dry environments.

中文翻译：

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五种长寿花园艺植物完整塑性体的比较和进化分析。

长寿花属的许多种是重要的园艺植物。它们进化出了景天酸代谢 (CAM) 光合途径，使它们能够更好地适应干燥环境。尽管它们很重要，但人们仍在争论长寿花是否是单系的，了解该属过去的多样化需要大量的努力和工作致力于该属的形态和分子特征的研究。然而，关于长寿花物种的分子信息，特别是塑料序列数据的报道很少，这对试图解释该属的进化史提出了巨大的挑战。在这项研究中，五种长寿花的塑性体，包括 Kalanchoe daigremontiana、Kalanchoe delagoensis、Kalanchoe fedtschenkoi、Kalanchoe longiflora、和Kalanchoe pinnata，进行了测序和分析。结果表明，这五种塑性体在大小、鸟嘌呤胞嘧啶 (GC) 含量和基因数量上都具有可比性，与景天科其他物种相比，这也表明差异不显着。在五个塑性体中鉴定出约224个简单序列重复（SSR）和144个长重复，其中大部分分布在反向重复区域。此外，还发现了包含单核苷酸多态性 (SNP) 或插入或缺失 (InDel) 突变的高度发散区域，这可能在未来的研究中用于建立长寿花属成员之间的系统发育关系。此外，系统发育分析表明应该将苔藓植物归入一个单一的属，如长寿花。进一步的基因组分析还表明，一些基因经历了正选择。其中，11个基因参与了细胞存活、电子传递等重要的细胞过程，可能在长寿花对干旱环境的适应性进化中发挥了不可或缺的作用。