Characterization and phylogenetic analysis of the chloroplast genome of Camellia albosericea (Theaceae)

To compare the chloroplast genome differences between Camellia albosericea and other congeneric species, and clarify the evolutionary position of C. albosericea within the genus Camellia, we sequenced and characterized its chloroplast genome using next-generation sequencing technology. This study aims to provide a scientific basis for species identification, genetic diversity analysis, and resource conservation of Camellia. Bioinformatics tools were integrated to perform sequence assembly, genome annotation, and characteristics analysis (including genome structure, codon bias, repeat sequences, simple sequence repeats SSRs) as well as analyses of functional region boundaries and phylogeny. The chloroplast genome of C. albosericea is 156,944 bp in length, exhibiting a typical quadripartite structure. A total of 134 genes were annotated, including 88 protein-coding genes, 37 tRNA genes, 8 rRNA genes, and 1 pseudogene. Codon usage analysis revealed a strong bias toward A/U-ending codons. Long repeat sequence analysis identified 43 repeats, and SSR detection yielded 244 SSR loci. Boundary comparison between C. albosericea and C. reticulata showed significant length differences in the ycf1 gene. Phylogenetic trees were constructed using maximum likelihood based on the complete chloroplast genome sequences of 28 Camellia species. The results indicated that C. albosericea clusters closely with C. borealiyunnanica, suggesting a close phylogenetic relationship between them. In conclusion, the basic characteristics of the C. albosericea chloroplast genome and its phylogenetic position reported herein provide critical support for developing molecular markers of sect. Camellia, clarifying interspecific relationships, and resolving the evolutionary process and taxonomic status of C. albosericea.