Genetic Diversity and Population Structure of Platonia insignis Across Amazon–Cerrado Ecotones: Implications for Conservation and Germplasm Management of a Fruit Tree

Platonia insignis Mart. (Clusiaceae) is a native fruit tree of great ecological and socioeconomic importance in the Brazilian Amazon and Cerrado. However, habitat loss is threatening its genetic variability. We investigated whether habitat fragmentation across the Amazon, Cerrado, and transition zones shapes the genetic diversity and population structure of five natural populations of P. insignis, using ISSR markers. Leaf samples from 13–15 individuals per population were collected, and DNA was extracted using the CTAB protocol. Twelve ISSR primers amplified 149 loci, used to estimate genetic parameters. AMOVA showed that 73.58% of genetic variation occurred within populations and 26.41% among populations (FST = 0.261). Amazonian populations exhibited the highest genetic diversity, while transition zone populations had the lowest values. The Cerrado population was genetically distinct and maintained moderate intrapopulation diversity. Bayesian clustering, PCoA, and UPGMA revealed three genetic groups corresponding to the sampled regions. Transitional populations showed high genetic admixture, indicating their role as potential corridors for gene flow. Our results highlight the need to preserve genetically diverse Amazonian populations, safeguard the Cerrado population as an evolutionarily significant unit, and maintain transitional populations to promote landscape connectivity. The study provides a genetic baseline to support conservation and management of P. insignis germplasm resources.