Comparative Analyses of Chloroplast Genome Provide Effective Molecular Markers for Species and Cultivar Identification in .

is popular in ornamental horticulture for its colorful bracts and excellent adaptability, but the complex genetic relationship among this genus is fuzzy due to limited genomic data. To reveal more genomic resources of , we sequenced and assembled the complete chloroplast (cp) genome sequences of 'Splendens'. The cp genome size was 154,869 bp in length, containing 86 protein-coding genes, 38 tRNAs, and eight rRNAs. Cp genome comparison across 12 species (, , , , , , , , , , , and ) revealed five mutational hotspots. Phylogenetic analysis suggested that published previously and clustered into one subclade as two distinct groups, sister to the subclade of 'Splendens'. We considered the phylogeny relationships between and to be controversial. Based on two hypervariable regions and three common plastid regions, we developed five molecular markers for species identification in and applied them to classify 53 ornamental cultivars. This study provides a valuable genetic resource for breeding and offers effective molecular markers to distinguish the representative ornamental species of .