Molecular diversity and population structure of Mediterranean fig (Ficus carica L.) germplasm: implications for conservation and climate-resilient breeding

Background: The common fig offers significant potential for addressing agricultural challenges, particularly in climate-vulnerable regions of Mediterranean countries and beyond. Its ease of propagation makes it a low-input solution for smallholder farmers. Here, we present a genetic analysis of 351 fig accessions from Mediterranean and underrepresented regions, using 11 polymorphic Simple Sequence Repeats loci to assess genetic diversity and population structure. Results: A total of 281 unique genotypes was identified, revealing substantial synonymy within the germplasm. Population STRUCTURE analysis detected three main genetic groups; however, overall structure was weak, with extensive admixture and limited geographic clustering, reflecting long-term human-mediated exchange and clonal propagation. These patterns were consistently supported by Principal Component Analysis and Analysis of Molecular Variance, confirming low genetic partitioning and the predominance of variation within genotypes. Importantly, the inclusion of Italian and, for the first time, Romanian germplasm expands current knowledge beyond existing genomic datasets, providing new insights into previously underrepresented genetic resources. The identification of rare and private alleles further highlights the presence of unique and potentially adaptive variation. Conclusions: Our findings demonstrate that fig germplasm harbors high and largely unstructured genetic diversity shaped by extensive gene flow and vegetative propagation. This study provides a complementary perspective to recent SNP-based analyses, highlighting the practical advantage of SSR markers for detecting clonal variation and for the cost-effective, scalable, and easily comparable management of germplasm collections. The identified diversity supports targeted conservation strategies (on-farm, in situ, and ex-situ) and represents a valuable resource for breeding climate-resilient cultivars in marginal environments. These findings contribute to global efforts aligned with Sustainable Development Goals, particularly SDG 2 (Zero Hunger) and SDG 13 (Climate Action).