RÉSUMÉ
Cajazeira (Spondias mombin L.), of the family Anacardiaceae, is a species of fruit tree found in the Amazon region with fruits that have excellent prospects for commercial use. We aimed to evaluate the genetic diversity within and among natural populations of S. mombin, with natural occurrence in northern Mato Grosso State, by using inter-simple sequence repeat (ISSR) markers. Overall, 126 individuals were evaluated from three populations located Alta Floresta (AFL) 42, Marcelândia (MAR) 41, and Nova Bandeirantes (NBA) 43. The individuals were genotyped with 14 ISSR primers, which amplified 99 fragments. All markers, with the exception of DiGA3'A, presented a polymorphic information content above 0.25, and thus, are recommended for diversity analyses in S. mombin. Genetic diversity of the AFL [Nei's diversity (H) = 0.2430 and Shannon index (I) = 0.3547] and MAR (H = 0.2062 and I = 0.2993) populations was higher when compared to the NBA population, which presented the lowest genetic diversity (H = 0.2002 and I = 0.2957). Analysis of molecular variance showed that 77.38% of the total genetic variation is found within populations while 22.62% is found among populations. AFL and NBA are genetically the most similar populations and also the closest "Structure" revealed genetic diversity among the genotypes of each population. As there is genetic variability in both populations, and there are no genetically identical individuals, both populations can be a source of genotypes for germplasm banks and for future commercial fruitful plantations S. mombin.