Genetic Diversity of Blueberry Genotypes Estimated by Antioxidant Properties and Molecular Markers.

Blueberries (Vaccinium spp.) have gained much attention worldwide because of their potential health benefits and economic importance. Genetic diversity was estimated in blueberry hybrids, wild clones and cultivars by their antioxidant efficacy, total phenolic and flavonoid contents, and express sequence tag-simple sequence repeat (SSR) (EST-SSR), genomic (G)-SSR and express sequence tag-polymerase chain reaction (EST-PCR) markers. Wide diversity existed among the genotypes for antioxidant properties, with the highest variation for DPPH radical scavenging activity (20-fold), followed by the contents of total flavonoids (16-fold) and phenolics (3.8-fold). Although a group of 11 hybrids generated the maximum diversity for antioxidant activity (15-fold), wild clones collected from Quebec, Canada, had the maximum variation for total phenolic (2.8-fold) and flavonoid contents (6.9-fold). Extensive genetic diversity was evident from Shannon's index (0.34 for EST-SSRs, 0.29 for G-SSR, 0.26 for EST-PCR) and expected heterozygosity (0.23 for EST-SSR, 0.19 for G-SSR, 0.16 for EST-PCR). STRUCTURE analysis separated the genotypes into three groups, which were in agreement with principal coordinate and neighbour-joining analyses. Molecular variance suggested 19% variation among groups and 81% among genotypes within the groups. Clustering based on biochemical data and molecular analysis did not coincide, indicating a random distribution of loci in the blueberry genome, conferring antioxidant properties. However, the stepwise multiple regression analysis (SMRA) revealed that 17 EST-SSR, G-SSR and EST-PCR markers were associated with antioxidant properties. The study is valuable to breeding and germplasm conservation programs.