INTRODUCTION

, a vulnerable species widely distributed in tropical and subtropical areas, has been recognized as a model plant for studying island conservation biology due to its fragmented habitat, slow growth, and ecological sensitivity. However, its organelle genome evolution and population divergence across different island environments remain poorly understood.

METHOD

In this study, we assembled and annotated the complete chloroplast (cp) and mitochondrial (mt) genomes of two geographically distinct individuals of from Hainan Island, China: a coastal area (SY) and a mountainous forest area (DF).

RESULTS

Both genomes showed conserved circular structures, but comparative analyses revealed key differences. The chloroplast genomes exhibited intergenic hotspot regions such as , , and , which may serve as potential markers for taxonomy, population genetics, phylogeography and conservation biology of . In the mitochondrial genomes, three genes (, , and ) showed the non-synonymous to synonymous substitution rate ratio (Ka/Ks) >1, indicating potential positive selection linked to environmental stress in the coastal population. Over 580 RNA editing sites were identified in each mitochondrial genome, with minor differences between DF and SY. These results suggest that while organelle genome structures are conserved, subtle molecular variations could potentially be associated with environmental differences between populations, although further investigation is needed to confirm adaptive significance.

CONCLUSION

This study provides foundational genomic resources for understanding the adaptive evolution of and supports conservation strategies in island ecosystems.