Evaluation of genetic diversity and population structure of Annamocarya sinensis using SCoT markers

Annamocarya sinensis (Dode) Leroy, a relict plant from the Tertiary period, is a member of Annamocarya genus in the Juglandaceae family. Despite its wide distribution in Guangxi Province, the habitats of this species had become fragmented and isolated, causing it facing deterioration. For protecting this endangered species, it is crucial to understand its status in the wild and genetic diversity. In this study, 216 A . sinensis accessions from 18 populations in Guangxi were examined using Start Codon Target Polymorphism (SCoT) markers for PCR amplification, genetic diversity, and population structure analysis. Out of the 20 SCoT primers used, 222 sites were amplified, with 185 being polymorphic (PPB of 83.33%). Polymorphic information content values ranged from 0.4380 to 0.4999, Nei’s genetic diversity index ranging from 0.1573 to 0.2503, and Shannon diversity index ranged from 0.1583 to 0.3812. Through AMOVA analysis, the total genetic diversity and genetic diversity within populations was calculated out as 0.3271 and 0.1542 respectively, the genetic differentiation coefficient between populations was 0.5286, with a gene flow 0.4458. Cluster analysis categorized A . sinensis germplasm into three groups, while population structure analysis divided all accessions into three ancestral sources with 19.91% showing mixed ancestral origins. No significant correlation was observed between genetic and geographical distance on the Mentel test (r = 0.07348, p = 0.7468). Overall, A . sinensis displays a relatively rich genetic diversity at the species level, albeit with a fairly uniform genetic background and high genetic differentiation. This study provides a crucial basis for the conservation and innovative use of A . sinensis germplasm resources.