The complete chloroplast genome of Scutellaria barbata D. Don 1825 revealed the phylogenetic relationships of the Scutellaria genus

Abstract

Scutellaria barbata D. Don 1825 is an important medicinal plant distributed in wetlands about 2000 m above sea level and used to treat various diseases. The complete chloroplast genome of S. barbata is 152,050 bp with four subregions consisting of a large single-copy region (84,053 bp), a small single-copy region (17,517 bp), and a pair of inverted repeats (25,240 bp). In the chloroplast genome of S. barbata, 131 genes were detected, comprising 87 protein-encoding genes, eight ribosomal RNA (rRNA) genes, and 36 transfer RNA (tRNA) genes. Phylogenetic analysis based on the complete chloroplast genome and protein-coding DNA sequences of 27 related taxa of the genus (out group included Holmskioldia sanguinea and Tinnea aethiopica) indicates that S. barbata was made a clade with S. orthocalyx, and S. meehanioides was a sister to them. The first chloroplast genome of S. barbata was reported in this work, serving as a potential reference for important medicinal plants within the Scutellaria genus.

Keywords: Chloroplast genome; Scutellaria barbata; phylogenetic relationships.

Figure 1.

Photographs of Scutellaria barbata D. Don. (These photographs were taken by Prof. Quan Zhang). The foliage of S. barbata exhibits triangular, ovate, or ovate-lanceolate shapes, characterized by a sharp apex and a broad wedge-shaped or nearly truncated base. The raceme of this species is inconspicuous and positioned terminally. The lower bracts are elliptic or narrowly elliptic, while the bracteoles take the form of needle-shaped structures. Furthermore, the corollas of Scutellaria barbata display a vivid purple-blue coloration. (A) Plant panorama of S. barbata and (B) the flowers of S. barbata.

Figure 2.

The circle map of chloroplast genome map of S. barbata. Distinctive colored boxes encircling the outer circle depict genes, with clockwise and counter-clockwise transcribed genes represented inside and outside the circle, respectively. The inner circle features a gray region indicating the GC content, while the quadripartite structure (LSC, SSC, IRA, and IRB) is illustrated on the inner circle accordingly.

Figure 3.

The maximum-likelihood phylogenetic tree of 25 Scutellaria species was constructed based on the CDS sequences extracted by IQ-TREE, with Tinnea aethiopica and Holmskioldia sanguinea added as outgroup. The phylogenetic tree was constructed using the maximum-likelihood method (ML) and bootstrap was performed 1000 times. The number on each branch indicates the boot support value. The following sequences were used: S. microviolacea MZ954872.1 (Wang et al. 2022), S. tsinyunensis MT544405.1 (Shan et al. 2021), S. franchetiana MW376478.1, S. calcarata MN128385.1 (Zhao et al. 2020), S. quadrilobulata MN128381.1 (Zhao et al. 2020), S. caryopteroides OP597816.1, S. forrestii OP597817.1, S. insignis KT750009.1, S. indica var coccinea MN047312.1 (Lee and Kim 2019), S. orthocalyx MN128383.1 (Zhao et al. 2020), S. meehanioides MW381011.1 (Zhang et al. 2021), S. mollifolia MN128384.1 (Zhao et al. 2020), S. lateriflora KY085900.1, S. scordifolia MT712016.1, S. tuberifera MW376477.1 (Shan et al. 2021), S. baicalensis MF521632.1 (Jiang et al. 2017), S. grandiflora OM397372.1, S. rehderiana MT982397.1, S. amoena MN165116.1 (Chen and Zhang 2019), S. likiangensis isolate S01 OP597811.1, S. likiangensis OL711695.1, S. kingiana MN128389.1 (Zhao et al. 2020), S. przewalskii MN128382.1 (Zhao et al. 2020), S. altaica MN128387.1 (Zhao et al. 2020), T. aethiopica MN128380.1 (Zhao et al. 2020), and H. sanguinea MN227130.1 (Lee and Kim 2020).