Unraveling the genetic diversity and evolutionary lineages of Catharanthus roseus cultivars through plastome analysis and DNA barcoding

Context This investigation elucidates the genetic heterogeneity and phylogenetic affinities among eight cultivars of Catharanthus roseus, focusing on petal color and morphological variations. Aims The primary objective was to elucidate the genetic disparities and evolutionary trajectories among these cultivars, thereby augmenting our comprehension of their genomic architecture and phylogenetic lineages. Methods The genomic DNA of the cultivars underwent sequencing, assembly, and annotation utilizing the bioinformatic tools NOVOPlasty and GeSeq. Key results Results showed minimal plastome size variation among cultivars (154,928 bp to 155,066 bp). Group 1 cultivars (1, 6, 8) had elongated petals, whereas Group 2 (2, 3, 4, 5, 7) had broader, orbicular petals. Sequence analysis showed significant variations in photosynthesis-related genes, with distinct single nucleotide polymorphism (SNP) frequencies and insertion/deletion (Indel) patterns between groups. The examination of codon usage and simple sequence repeat (SSR) biomarkers did not yield significant contributions to understanding the speciation process. Phylogenetic relationships were determined using DNA barcoding and key plastid markers (matK, rbcL, trnL). The trnL gene effectively clustered cultivars by petal morphology. Phylogenetic trees showed close genetic relationships within the same tribe, with C. roseus being genetically distinct from other species. Conclusions This study has provided comprehensive chloroplast genome assemblies for C. roseus cultivars, advancing our understanding of their genetic diversity and phylogenetic relationships. Implications The findings enhance our comprehension of speciation mechanisms within the Apocynaceae family and offer important insights for the refinement of taxonomic frameworks, contributing to a deeper evolutionary perspective on the diversification of C. roseus and related species.