Genetic diversity of natural populations of Phyllanthus emblica and its correlation with habitat factors in Guangxi

This study utilized SSR markers to assess the genetic diversity and structure of natural Phyllanthus emblica populations in Guangxi, China, and revealed habitat factors influencing genetic variation, aiming to provide a theoretical foundation for germplasm conservation and elite variety breeding of P. emblica.

Genetic diversity and population structure of P. emblica were analyzed across 18 natural populations (398 individuals) from Guangxi using 13 SSR primer pairs. Genetic analyses were performed with PolyGene, GenAlEx and STRUCTURE software, and correlation heatmaps were generated using R software.

A total of 145 alleles were detected across 13 SSR loci, with an average of 11.154 alleles per locus. The mean observed heterozygosity (H_o), expected heterozygosity (H_e), polymorphism information content (PIC), and Shannon-Wiener diversity index (I) for each locus were 0.515, 0.635, 0.595, and 1.412, respectively. Among the 18 populations, BSLL exhibited the highest genetic diversity, with H_e and I of 0.630 and 1.327, while GLPL showed the lowest, with H_e and I of 0.494 and 0.875, respectively. Dry-hot valley populations displayed significantly higher H_e and I than humid area populations. Genetic diversity was significantly positively correlated with temperature-related factors (Bio6: minimum temperature of the coldest month; Bio8: mean temperature of the wettest quarter; Bio11: mean temperature of the coldest quarter) and negative correlation with precipitation-related variables (Bio12: Annual precipitation; Bio13: precipitation of the wettest month; Bio19: precipitation of the coldest quarter). Analysis of molecular variation (AMOVA) indicated that 9.134% of genetic variation occurred among populations, while 90.866% within populations. STRUCTURE analyses (Delta K=2, 3, 4) consistently group dry-hot valley populations into a distinct cluster, demonstrating significant differentiation from humid area population.

Natural P. emblica populations in Guangxi possess moderate genetic diversity, with significant inter-population differentiation. Notably, dry-hot valley populations are genetically distinct from humid area populations, driven by divergent temperature and rainfall regimes. Therefore, it is recommended to implement targeted conservation strategies, including germplasm collection, preservation, and utilization-specific to distinct ecotypes such as dry-hot valley and humid area populations. This approach will effectively conserve genetic diversity and facilitate the rational exploitation of germplasm resources for future breeding programs.