Genetic diversity and population structure of sour passion fruit in Brazil

Sour passion fruit (Passiflora edulis) is the most economically important species in the genus Passiflora, mainly due to its edible fruit. Genetic diversity and population structure were analyzed in five P. edulis populations, each comprising 25 individuals, using 28 ISSR molecular markers. The markers exhibited high efficiency and informativeness, with an effective multiplex ratio of 13.99 and a marker index of 3.39. Germplasm included three commercial cultivars (BRS-RC Rubi do Cerrado, FB300-Araguari, and IAC-273/277) and two populations collected from production areas (Bahia and Rio de Janeiro, Brazil). Cluster and Bayesian structure analyses revealed clear genetic differentiation, dividing the accessions into five distinct groups corresponding to their populations of origin. The expected heterozygosity (He) and Shannon's information index (I) varied from He = 0.166 and I = 0.249 to He = 0.203 and I = 0.308. Overall genetic parameters confirmed this structure, with high coefficient of genetic differentiation (0.421) and limited gene flow (0.343 migrants per generation), indicating that 42.1 % of the total genetic variation resides among populations. This finding was consistent with the analysis of molecular variance, which accounted for 45 % of the variation among populations and 55 % within them. Principal coordinates analysis revealed five distinct groups, and the first two principal coordinates analysis axes accounted for 36.8 % of the variation. This study revealed significant genetic diversity and a strong population structure within the analyzed germplasm. These findings highlight its potential as a valuable genetic resource for future Passiflora breeding programs, especially for traits related to fruit quality and adaptation to diverse environmental conditions.