Variations in chlorogenic acid levels in an expanded gene pool of blueberries

Blueberry (Vaccinium spp.) fruit is a rich source of chlorogenic acid (CA), among other polyphenolics, which have been associated with human health maintenance and chronic disease prevention. This study was designed to examine variation in CA over a wide range of blueberry genotypes (different species and genetic backgrounds) including commercial cultivars, breeding selections and breeding populations that contributed to current commercial cultivars. Fully ripe fruit was evaluated for CA concentration in two successive years, and concentrations ranged from 33-71 and 58-139 mg/100 g (frozen fruit) in southern highbush (4×) and rabbiteye (6×) blueberry commercial cultivars, respectively. In the breeding selections (4×), which comprised an expanded gene pool, the CA ranged from 33-107 mg/100 g. Further gene pool expansion associated with the establishment of the breeding populations (4×) resulted in a wide range of CA concentrations with significant increases (up to 156 mg/100 g) compared to current commercial cultivars (4×). Ploidy level had a strong correlation (r = 0.7) with CA accumulation in the blueberry genotypes investigated in this study, and a significant positive correlation between CA level and anthocyanin level in blueberry was also observed (r = 0.30, 0.51. and 0.49 for commercial cultivars, breeding selections, and breeding populations, respectively). The large variation in CA accumulation indicated that significant genetic variation for CA exists among blueberry species which can be successfully utilized in breeding programs to aid in developing phytochemically-enhanced blueberry varieties.