Dynamic changes of enzymes involved in sugar and organic acid level modification during blueberry fruit maturation

In blueberry, sugars and organic acids determine fruit organoleptic quality and drastically change during fruit maturation. This study examined enzymes involved in the metabolism of sugars and organic acids during the three maturation phases (green, pink and blue). During maturation, an increase in sugar (mainly fructose and glucose) was associated with up-regulation of VcSPP (CUFF.32787.1), VcSPS (CUFF.14989.1), and VcINV (gene.g3367.t1.1, CUFF.8077.1 and CUFF.47310.2). A decrease in citrate was associated with VcACLY (CUFF.27347.1 and CUFF.28772.1) in the acetyl-CoA pathway and with VcGAD (CUFF.15663.1 and CUFF.13757.1) and VcGLT (CUFF.6416.1) in the GABA shunt. A decrease in malate was associated with VcMDH (CUFF.30072.1, CUFF.18332.1 and CUFF.24878.1) involved in malate biosynthesis, and with VcADH (gene.g1507.t1.1, CUFF.3210.1 and gene.g30667.t1.1) as well as VcPDC (CUFF.47532.1) involved in fermentation. Multi-isoforms of enzymes were divergent and differentially regulated, suggesting that they have specialized functions in these pathways. The information will contribute to the understanding of blueberry organoleptic quality.