The complete chloroplast genomes of Polygonatum hunanense, P. verticillatum, and P. caulialatum and their phylogenetic positions

Abstract

Polygonatum hunanense H.H. Liu & B.Z. Wang (2021) and P. verticillatum (L.) All. (1875) have been widely used as foods and as folk medicines in China and India, and P. caulialatum S. R. Yi (2021) has recently been described as a new medical plant in China. There is at present a lack of genome information regarding the species. Hence, this study reports the complete chloroplast genomes of the three species. The genomes of P. hunanense, P. verticillatum, and P. caulialatum were 155,583 bp, 155,650 bp, and 155,352 bp in length, respectively. They contained large single-copy (LSC) regions of 84,412 bp, 84,404 bp, and 84,285 bp, small single-copy (SSC) regions of 18,427 bp, 18,416 bp, and 18,463 bp, and a pair of inverted repeats of 26,372 bp, 26,415 bp, and 26,302 bp, respectively. The chloroplast genomes of P. hunanense, P. verticillatum, and P. caulialatum had 133 (103 unique) genes, consisting of 87 protein-coding genes, 38 ribosomal ribonucleic acid (RNA) genes, and eight transfer RNA genes, respectively. A maximum-likelihood phylogenetic tree showed that P. kingianum Coll. et Hemsl. var. grandifolium D.M. Liu & W.Z. Zeng (1991) was closer to P. cyrtonema Hua (1892) rather than to P. kingianum Coll. et Hemsl. (1890), further supporting its status as a unique species of the genus. Moreover, P. verticillatum was separated from the easily confused herb P. cirrhifolium (Wall.) Royle (1839), while P. caulialatum was closest to P. humile Fisch. ex Maxim. (1859). This research provides a foundation for further study of these herbs.