College of Life Sciences, Henan Normal University, Xinxiang 453000, China; Systematic & Evolutionary Botany and Biodiversity Group, MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Laboratory of Plant Germplasm and Genetic Engineering, School of Life Sciences, Henan University, Kaifeng 475001, China.
Mol Phylogenet Evol. 2024 Aug;197:108093. doi: 10.1016/j.ympev.2024.108093. Epub 2024 May 11.
Mulberries (genus Morus), belonging to the order Rosales, family Moraceae, are important woody plants due to their economic values in sericulture, as well as for nutritional benefits and medicinal values. However, the taxonomy and phylogeny of Morus, especially for the Asian species, remains challenging due to its wide geographical distribution, morphological plasticity, and interspecific hybridization. To better understand the evolutionary history of Morus, we combined plastomes and a large-scale nuclear gene analyses to investigate their phylogenetic relationships. We assembled the plastomes and screened 211 single-copy nuclear genes from 13 Morus species and related taxa. The plastomes of Morus species were relatively conserved in terms of genome size, gene content, synteny, IR boundary and codon usage. Using nuclear data, our results elucidated identical topologies based on coalescent and concatenation methods. The genus Morus was supported as monophyletic, with M. notabilis as the first diverging lineage and the two North American Morus species, M. microphylla and M. rubra, as sister to the other Asian species. In the Asian Morus species, interspecific relationships were completely resolved. However, cyto-nuclear discordances and gene tree-species tree conflicts were detected in the phylogenies of Morus, with multiple evidences supporting hybridization/introgression as the main cause of discordances between nuclear and plastid phylogenies, while gene tree-species tree conflicts were mainly caused by ILS.
桑树（桑属，蔷薇目，桑科）是重要的木本植物，因其在养蚕业中的经济价值，以及其营养价值和药用价值而受到重视。然而，桑属的分类学和系统发育，特别是对于亚洲种，由于其广泛的地理分布、形态可塑性和种间杂交，仍然具有挑战性。为了更好地了解桑属的进化历史，我们结合质体基因组和大规模核基因分析来研究它们的系统发育关系。我们组装了质体基因组，并从 13 种桑属物种和相关类群中筛选了 211 个单拷贝核基因。桑属物种的质体在基因组大小、基因内容、同线性、IR 边界和密码子使用方面相对保守。利用核数据，我们的结果基于合并和串联方法阐明了相同的拓扑结构。桑属被支持为单系群，Morus notabilis 是第一个分支的谱系，而北美两个桑属物种，Morus microphylla 和 Morus rubra，与其他亚洲物种是姐妹关系。在亚洲桑属物种中，种间关系得到了完全解决。然而，在桑属的系统发育中检测到核质不和谐和基因树种系树冲突，有多个证据支持杂交/渗入是核质系统发育不和谐的主要原因，而基因树种系树冲突主要是由 ILS 引起的。
