Genome-wide association studies for antioxidant activity in blueberry

Blueberry (Vaccinium spp.) is one of the most important small fruit crops due to its taste and its antioxidant capacity.

To understand the genetic basis of these antioxidant properties, we evaluated the antioxidant activity of 156 diverse blueberry genotypes, including cultivars, hybrids, and wild clones. Phenotypic characterization revealed diverse antioxidant activities ranging from 0.088 to 1.338 mg gallic acid equivalent per gram of fresh leaf weight. On average, 94.51% of the sequences were mapped to the blueberry reference genome. A total of 66,216 genome-wide single-nucleotide polymorphisms (SNPs) were obtained by sequencing and used for genome-wide association studies (GWAS). GWAS with a Fixed and Random Model Circulating Probability Unification model using the Genomic Association and Prediction Integrated Tool in R revealed 9 SNPs significantly associated with the antioxidant activity of blueberry. Functional annotation using BLASTx resulted in three SNP-containing regions producing hits in the NCBI nonredundant protein database. These proteins have been shown to be involved in various developmental processes and responses to biotic and abiotic stress in plants. The remaining six SNP-containing regions resulted in 4,577 RNA hits, consisting of multiple types of RNA molecules. Therefore, complex antioxidant activity is affected by both protein and RNA in blueberry plants.

Overall, our study provides a valuable allele pool to support the improvement of blueberry quality, mainly focused on antioxidant activity.