Genetic diversity of the endemic Durian Kura-kura (Durio testudinarius Becc.) using morphology and SSR markers

Abstract Durio testudinarius, commonly known as Durian kura-kura, represents a wild durian species within the Malvaceae family, exclusive to Borneo. Understanding the genetic diversity of this species is crucial for effective genetic resource management. In this study, we conducted a comprehensive analysis of the genetic diversity of D. testudinarius across five populations in West Kalimantan, namely Sambas, Landak, Sanggau, Sekadau, and Ketapang. Our approach integrated both morphological and molecular markers, incorporating 18 vegetative morphological characters and 20 microsatellite loci. Morphological analysis revealed variations among D. testudinarius accessions, encompassing traits such as tree height, leaf blade dimensions, trunk surface features, and various leaf characteristics. On the molecular level, all 20 microsatellite loci exhibited polymorphism, with allele frequencies ranging from 0.025 to 0.975. These loci collectively comprised 84 alleles across 20 accessions, averaging 4.2 alleles per locus. The observed heterozygosity and expected heterozygosity values were 0.263 and 0.268, respectively. Polymorphic information content values ranged from 0.049 to 0.869, with an average of 0.454. Ward-based cluster analysis using morphological, SSR, and combined markers generated a dendrogram, indicating that the Landak, Sekadau, and Sanggau populations tended to cluster together, while the Sambas and Ketapang populations exhibited a tendency to form distinct groups. This study provides valuable insights into the genetic diversity of Durio testudinarius, facilitating informed conservation and management strategies for this unique wild durian species in Borneo.