Exploring the Complete Chloroplast Genome of Pyrola decorata Andres: Structure, Variability, Phylogenetic Relationship.

Pyrola decorata Andres (P. decorata) is a traditional medicinal plant in China. However, its chloroplast genome and the deep evolutionary relationships among its genus remain unexplored. This study identified the samples as P. decorata using morphological observations from Flora of China (FOC) and ITS sequences. It is the first to analyze the complete chloroplast genome of P. decorata using Illumina and Nanopore sequencing technologies, confirming a typical chloroplast dumbbell structure. The chloroplast DNA (cpDNA) of P. decorata is 179,999 bp in length, consisting of a large single copy (LSC) (62.3% of total length (112,150 bp)), a small single copy (SSC) (6.5% of total length (11,701 bp)), and two inverted repeat regions (IRA and IRB) (31.2% combined (28,074 bp × 2)). Functional annotation revealed 128 genes: 77 conserved coding sequences (CDS) genes, 43 transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. Phylogenetic analysis placed P. decorata, Pyrola atropurpurea (P. atropurpurea), Pyrola rotundifolia (P. rotundifolia), and Chimaphila japonica within Group I, with P. decorata exhibiting the closest chloroplast genomic affinity to P. atropurpurea. These findings integrate morphological and molecular evidence to facilitate further identification, classification, and evolutionary analysis of this genus.