Abstract
Evaluating the genetic variability of germplasms is essential for enhancing and developing superior cultivars. However, there is limited information on cultivated germplasm diversity for Australian passion fruit breeding programs. The genetic diversity of Australian passion fruit (Passiflora spp.), including 94 rootstocks and 95 scions, was evaluated to support breeding programs aimed at enhancing productivity, fruit quality, and overall crop resilience. Rootstocks were genotyped using high-density 24k Diversity Arrays Technology (DArT)-based single-nucleotide polymorphism (SNP) markers, while genetic characterization of scions was conducted using eight simple sequence repeat (SSR) markers. The resulting genetic relationships revealed significant variation within rootstock populations. Bayesian cluster analysis in STRUCTURE showed that the rootstock population was divided into six distinct genetic groups, whereas only two subpopulations were identified among the scion accessions. SNP-based genotyping further highlighted the allelic diversity of Australian rootstocks, suggesting a rich reservoir of genetic traits for rootstock improvement. These findings underscore the importance of preserving and utilizing genetic diversity in Australian passion fruit germplasm to drive the development of superior cultivars with enhanced adaptability and performance under diverse environmental conditions.