Molecular systematics of Caryopteris (Lamiaceae) and its allies with reference to the molecular phylogeny of subfamily Ajugoideae

Abstract

Ajugoideae, the third–largest subfamily of Lamiaceae with 23 genera and about 760 species, is distributed worldwide, but is primarily found in tropical regions. During the past two decades, substantial progress has been made towards discerning phylogenetic relationships and generic boundaries in Ajugoideae, but major questions still remain. This phylogenetic study was conducted using 422 DNA sequences from seven DNA regions (nrITS, ETS, and matK, rbcL, rps16, trnL–trnF, trnH–psbA) representing 50 species from 22 of 23 genera in Ajugoideae, to reconstruct the backbone phylogeny of the subfamily, with emphasis on phylogenetic relationships among Caryopteris, Schnabelia and their closest allies. Key results: (1) Ajugoideae is monophyletic and can be divided into four main clades. (2) Discretitheca and Glossocarya, which have not been included in any previous molecular analysis, are members of Ajugoideae and closely related to Karomia and Rotheca. (3) Expanded Schnabelia is monophyletic, sister to Rubiteucris, and consists of two morphologically distinct clades, recognized here as sect. Cylindricaulis and sect. Schnabelia. (4) Traditionally defined Caryopteris is confirmed to be polyphyletic, with several segregate genera. (5) Recircumscribed Caryopteris was found to be monophyletic, but intrageneric relationships were not fully resolved. Synapomorphies of Caryopteris include boat–shaped nutlets that are winged along the edge, fimbriate anterior corolla lobes, and suprareticulate pollen sculpturing. Caryopteris forrestii var. minor was elevated to species rank based on molecular and morphological evidence.

Leveraging plastomes for comparative analysis and phylogenomic inference within Scutellarioideae (Lamiaceae)

“…Our study is the first to use complete plastome sequences to reconstruct the phylogeny of Scutellarioideae. The phylogenetic tree obtained here is largely consistent with previous studies based on the plastid DNA markers [1,9,97,98]. However, some phylogenetic relationships within Lamiaceae differ from recent nuclear trees [99].…”

“…Despite the limited sampling, our study, based on complete plastomes, presents a more resolved and better supported phylogeny of Scutellarioideae than previous studies [1,9,18,43,98]. All the phylogenetic trees inferred from the complete plastome sequences have higher resolution (Fig 8) than trees based on the six commonly used chloroplast DNA regions (matK, ndhF, rbcL, rpL32-trnL, rps16-intron, and trnL-F; S7 Fig…”

Revisiting the phylogeny of Dipsacales: New insights from phylogenomic analyses of complete plastomic sequences

“…In addition, we also included some extra genes and regions (i.e., accD, ndhB, ndhK, rps7, ycf5, atpF-atpH, petB-petD, and petN-psbM) that were not used by Clement et al (2014) for analyses. The removal of problematic alignment regions can lead to better trees (Talavera & Castresana, 2007), so ambiguously aligned positions (e.g., characters of uncertain homology among taxa and single-taxon insertions; see also Chen et al, 2016;Drew et al, 2017;Hu et al, 2018;Xiang et al, 2018) were removed manually in our analyses (Tables S1, S2). The corresponding datasets are indicated by "−M" subscript in Table 2.…”

The complete chloroplast genome of Caryopteris incana (Lamiaceae) and phylogenetic analysis

“…is the most widespread species occurring throughout East Asia. This species is a perennial herb to small woody shrub distribute in China, Japan, and the Korean Peninsula (Ando et al 2015;Xiang et al 2018). In East Asia, this species, due to its anti-inflammatory properties, has been widely used as a traditional medicine for the relief of colds, pertussis, eczema, itchy skin, and venomous snake bites (Mao et al 2016).…”