Complete Chloroplast Genome Analysis of Casearia kurzii: Gene Loss at the IR Boundary and Monophyletic Evolution Within Casearia

Genomic analysis is crucial for understanding the evolutionary history, phylogenetic relationships, and effective conservation of plant species. Casearia kurzii is an important medicinal plant of the genus Casearia, but its complete chloroplast genome has not previously been reported, limiting genetic studies and conservation efforts. In this study, we assembled and annotated the complete chloroplast genome of C. kurzii using Illumina sequencing technology and conducted a comparative genomics analysis with 14 closely related species to clarify its phylogenetic position within Casearia. The chloroplast genome was 157,998 bp, showing a typical quadripartite structure. Key findings included: (1) the loss of the rpl22 gene at the IR boundary; (2) the identification of 60 simple sequence repeats (SSRs) and (3) the discovery of five candidate molecular markers for species-level identification. Phylogenetic analysis revealed that C. kurzii formed a strongly supported monophyletic clade (100% bootstrap support) with C. velutina, C. decandra, and C. glomerata, this clade originated approximately 15.8 million years ago. This study provides molecular tools for accurate identification and conservation of C. kurzii and related species, laying the foundation for exploring adaptive evolution within Casearia and advancing comparative genomics research.