The complete chloroplast genome of Lonicera hypoglauca Miq (Caprifoliaceae: Dipsacales) from Guangxi, China

Abstract Lonicera hypoglauca Miq, which is widely distribute in south China, is an important Chinese plant used in traditional medicine. Here we report the first complete chloroplast (cp) genome sequence of this species. The circular cp genome is 154,581 bp in size, including a large single-copy (LSC) region of 88,379 bp and a small single-copy (SSC) region of 18,646 bp, which were separated by two inverted repeat (IR) regions (IRA and B, 23,778 bp each). A total of 121 genes were annotated, including 8 ribosomal RNAs (rRNAs), 33 transfer RNAs (tRNAs) and 80 protein-coding genes (PCGs). Phylogenetic analysis of 20 representative members within the Caprifoliaceae showed that L. hypoglauca is closely related to the Lonicera macranthoides. This study provides important genetic information for future systematic and evolutionary studies of L. hypoglauca.

Lonicera hypoglauca Miq, which is classified in the Caprifoliaceae, is widely distributed in southern China and Japan. The flower bud (rich in chlorogenic acid) of this plant is used as an herbal medicine and has been prescribed to treat various infectious diseases, such as fever, febrile blood dysentery and throat numbness (Zhang et al. 2008;Li et al. 2015). Pheophytin a, which can be extracted from the L. hypoglauca leaves, is an effective inhibitor of chronic hepatitis C virus NS3 protease ). Some compounds (Bisflavonoid and loniceraflavone) in the leaves of L. hypoglauca significantly inhibit the activity of xanthine oxidase (Chien et al. 2009). Although the medicinal effect of L. hypoglauca have been fully studied, the complete chloroplast (cp) genome of L. hypoglauca has not been reported. In this research, we assembled and determined the cp genome sequence of L. hypoglauca as a resource for future study of this medicinal plant.
Young and healthy leaf samples were collected from Guangxi Botanical Garden of Medicinal Plants, Nanning, Guangxi Zhuang Autonomous Region, China (22 51 0 17.77 00 N, 108 24 0 48.15 00 E, 95 m above sea level). The leaf specimen (accession number: GZNUYZW202002001) was deposited in the herbarium of School of Life Sciences, Guizhou Normal University (Jinghua Mu, 842422147@qq.com). The total genomic DNA (No. YZW202002002) was extracted using the DNAsecure Plant Kit (TIANGEN, Beijing) and stored at À80 C in the laboratory (room number: 1403) of School of Life Science, Guizhou Normal University. A total concentration of 800 ng of DNA served as the input material for the DNA sample preparations. Sequencing libraries were generated using NEB Next V R Ultra DNA Library Prep Kit for Illumina V R (NEB, USA). The library preparations were sequenced on an Illumina platform and 150 bp paired-end reads were generated. The filtered reads were assembled using the program GetOrganelle (Jin et al. 2019) with Lonicera macranthoides (GenBank accession number: MH579750) as the reference genome. The assembled cp genome was annotated using the online software GeSeq (Tillich et al. 2017). The complete chloroplast genome sequence was submitted to GenBank under the accession number MW186761.
To further understand the phylogenetic history of L. hypoglauca, 20 cp genome sequences of the Caprifoliaceae (12 Lonicera species, 1 Heptacodium species, 1 Triosteum specie, 2 Dipelta species, 1 Weigela species and 3 Patrinia species) were downloaded from GenBank to construct the phylogenetic trees through maximum-likelihood (ML) analysis. The ML tree was performed using RAxML (Version 8.0.19, Model: GTRGAMMA) (Stamatakis 2014) with 1,000 bootstrap replicates. The phylogenetic tree indicated that L. hypoglauca was fully resolved in a clade with L. macranthoides, sister to two other species of Lonicera, L. confusa and L. japonica (Figure 1). Compared to other Flos Lonicerae members, L. hypoglauca was also fully resolved in a clade with L. macranthoides according to rbcL gene sequence analysis (Li et al. 2012). Because of the closely evolutionary relationship between L. macranthoides and L. hypoglauca, in comparison with other DNA barcodes, only the psbA-trnH intergenic spacer sequence had appropriate mutation sites to distinguish L. macranthoides and L. hypoglauca (Sun et al. 2011).

Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
This study was supported by the National Natural Science Foundation of China under Grant [No. U1812401, 32060068], and the Guizhou Provincial Science and Technology Foundation under Grant [No. 2020-1Y096].

Data availability statement
The complete chloroplast genome data that support the findings of this study are openly available in GenBank of NCBI at [https://www.ncbi.nlm. nih.gov] (https://www.ncbi.nlm.nih.gov/) under the accession number MW186761. The associated BioProject, SRA, and Bio-Sample numbers are PRJNA674956, SRX9460983, and SAMN16684231, respectively.