Abstract:
Salsola represents a globally distributed lineage across arid and semi-arid regions and encompasses pronounced diversity in photosynthetic pathways, while remaining taxonomically contentious. In this study, the chloroplast (cp) genome of
Oreosalsola laricifolia (Litv. ex Drobow) Akhani, a C
3-C
4 intermediate species, was generated through high-throughput sequencing, followed by
de novo assembly and comprehensive annotation. Comparative genomic analyses incorporated 17 previously published chloroplast genomes from
Salsola sensu lato, and phylogenetic relationships were reconstructed based on the complete chloroplast genome sequences. Results showed that the chloroplast genome of
O. laricifolia was 151 880 bp and encoded 132 genes. Across all 18 genomes, structural organization, genome length, GC content, gene composition, and codon usage patterns remained highly conserved. Ten hypervariable regions and 1 131 simple sequence repeats were identified as candidate molecular markers for population genetics studies. Phylogenetic reconstruction robustly supported the segregation of
Pyankovia,
Climacoptera, and
Caroxylon from the traditional
Salsola, while revealing topological discordance relative to earlier molecular frameworks. Patterns of divergence further suggested that shifts in photosynthetic pathways contributed to intraspecific divergence within
Oreosalsola. Collectively, these findings enrich the genetic resources for
O. laricifolia and refine current understanding of chloroplast genome evolution and phylogenetic relationships within this challenging genus.