Plastome comparison and phylogenomics of Chinese endemic Schnabelia (Lamiaceae): insights into plastome evolution and species divergence

作者：Shengnan Wei, Jianan Ying, Lu Ming, Jie Li, Yanbo Huang, Zhenming Wu, Paul G. Nevill, Pan Li, Xinjie Jin, Qixiang Lu · 发表于：BMC Plant Biology · 年份：2025 · DOI：10.1186/s12870-025-06647-y · 被引用次数：3 · 研究领域：Genomics and Phylogenetic Studies、Plant Diversity and Evolution、Chromosomal and Genetic Variations

BACKGROUND: Schnabelia species, herbaceous perennial plants within the Lamiaceae family, possess medicinal value and are endemic to China. While previous studies have focused on morphological classification, molecular systematics, and medicinal components, there has been limited research on phylogenomics. To reveal their plastid genome characteristics and phylogenetic relationships, we sequenced and assembled the plastomes of all five Schnabelia species (S. oligophylla, S. tetrodonta, S. nepetifolia, S. terniflora, S. aureoglandulosa), conducted comparative genomic analyses, and constructed a phylogenetic tree incorporating closely related taxa in subfamily Ajugoideae, as well as conducting divergence time estimation. RESULTS: Plastome size of the five species ranged from 155,733 bp to 156,944 bp, encompassing 115 unique genes, with a GC content of 37.8% same for all species. Five intergenic spacer regions (trnH-GUG-psbA, trnK-UUU-matK, petB-petD, ndhD-psaC, ndhA-ndhH) were identified as divergence hotspots. Gene selection pressure analysis demonstrated that all genes were under negative selection. Phylogenetic relationship of Ajugoideae species based on plastomes confirmed the monophyly of Schnabelia. Two clades within Schnabelia were supported, one containing two original species and the other comprising three species transferred from Caryopteris. The stem age of the Schnabelia is estimated to be approximately 30.24 Ma, with the split of two Sections occurring around 12.60 ...