ASHS 2025 Conference

As a native species in the southeastern U.S., rabbiteye blueberry (Vaccinium virgatum Aiton) is known for its resilience to environmental stresses and adaptability to various soil types. Rabbiteye was the dominant species grown in the southern U.S. before the rise of southern highbush blueberries (V. corymbosum L. interspecific hybrids). Compared to southern highbush, rabbiteye cultivars are often perceived as seedy and have thick skin. Limited genetic diversity, compounded by repeated use of elite parents and decreased breeding efforts, poses challenges for rabbiteye improvement. To facilitate more efficient rabbiteye breeding in the future, this study aims to assess the genetic diversity of rabbiteye cultivars through pedigree analysis and evaluate the impact of interspecific hybridization on modern cultivars. The pedigree data of 180 rabbiteye blueberry accessions were analyzed to calculate inbreeding coefficients, coefficients of coancestry and the genetic contribution of founders. Five founders ‘Myers’, ‘Black Giant’, ‘Ethel’, ‘Clara’, and ‘W4’, collectively account for a minimum of 73% of the genetic composition of rabbiteye cultivars. The level of interspecific hybridization has been limited in rabbiteye breeding, with V. corymbosum contributing 3% of the genetic composition of rabbiteye cultivars and 1% from other species such as V. constablaei and V. darrowii. The narrow genetic base and repeated use of common parents led to an increase in inbreeding coefficients, from an average of less than 0.0002 before 1980 to 0.014 in the 2000s. In the future, it would be valuable to increase the use of exotic materials from other species or within the rabbiteye germplasm to broaden the genetic base while introducing valuable alleles. Further evaluation of population structure with genomic information is needed to validate pedigree information and provide a more accurate assessment of the genetic diversity and population structure.