Integrating Genetic and Environmental Diversity to Evaluate an Ex Situ Germplasm Collection of Passiflora cincinnata from the Brazilian Caatinga

Ex situ germplasm collections are essential for conserving plant genetic resources, but their effectiveness depends on how well they represent the genetic and environmental diversity of natural populations. Passiflora cincinnata Mast., an endemic wild passion fruit species from the Brazilian Caatinga, is an important source of adaptive traits for conservation and breeding under semi-arid conditions. This study evaluated the genetic diversity and environmental diversity represented by 55 accessions maintained in the Active Passion Fruit Germplasm Bank of Embrapa Semiárido. Genetic diversity was assessed using eight ISSR primers, percentage of polymorphic loci, Shannon’s information index, expected heterozygosity (He), UPGMA clustering, principal coordinate analysis (PCoA), analysis of molecular variance (AMOVA), and Mantel tests. Environmental characterization was based on WorldClim bioclimatic variables, principal component analysis (PCA), k-means clustering, and PERMANOVA. Substantial genetic diversity was detected across the collection, with an overall expected heterozygosity (He) of 0.444 and 100% polymorphic loci. Most genetic variation occurred within biogeographical domains (97.1%), whereas differentiation among domains was low (PhiPT = 0.029; p = 0.124). Five distinct climatic groups were identified, reflecting contrasting temperature and precipitation regimes across the Caatinga. The integration of molecular and environmental analyses showed that the collection encompasses substantial genetic diversity and broad environmental variation, providing complementary information for conservation planning, germplasm management, and climate-resilient passion fruit breeding.