Transcriptional Changes of Anthocyanin Metabolism during Fruit Ripening in Highbush Blueberry (Vaccinium corymbosum L.)

Transcriptional changes of anthocyanin metabolism during fruit ripening were examined based on the gene expression and metabolite profiling in ‘Bluecrop’ highbush blueberry. Fruits were categorized into mature green, veraison, and dark blue stages. Genes involved in anthocyanin metabolism were identified in the fruit transcriptome analyzed by using RNA-Seq. Transcriptional changes of these genes were investigated by differentially expressed genes. Total anthocyanin content was determined by pH differential method using UV/Vis spectrophotometer and anthocyanin aglycon content was determined by high performance liquid chromatography. Individual anthocyanins were profiled by liquid chromatography-mass spectrometry. Of 38,025 contigs, 33 genes involved in anthocyanin metabolism were identified. Anthocyanins were glucosylated and/or methylated by 8 transferase genes during fruit ripening. Gene expression involved in anthocyanin metabolism was correlated with the increase of anthocyanin content during fruit ripening. A total of 18 anthocyanins composed of cyanidin, delphinidin, malvidin, peonidin, and petunidin were identified at dark blue stage. These results provide information to understand anthocyanin metabolism during fruit ripening in highbush blueberry.