The complete plastid genome of Polygonatum gracile P. Y. Li (Asparagaceae): characterization and phylogeny.

Polygonatum gracile P. Y. Li is a perennial rhizomatous medicinal herb endemic to China with recognized medicinal value. Here, the first complete plastid genome of P. gracile is reported and characterized, and the phylogenetic relationships of P. gracile with other Polygonatum species are clarified by phylogenetic inferences based on complete plastid genome sequences. The complete plastid genome of P. gracile is 155,734 bp in length and exhibits the typical quadripartite circular structure consisting of a large single-copy (LSC, 84,385 bp) region, a small single-copy (SSC, 18,519 bp) region, and a pair of inverted repeat regions (IRa/b, 26,415 bp). A total of 112 unique genes, including 78 protein-coding genes, 30 tRNA genes, and four rRNA genes were identified. Seven protein-coding genes, eight tRNA genes, and four rRNA genes were duplicated in the IR regions. Phylogenetic reconstructions indicated that P. gracile belongs to sect. Verticillata and is most closely related to P. zanlanscianense Pamp. This study provides a basis for further phylogenetic reconstructions, conservation and utilization of Polygonatum species.