The interaction between DcCaM7 and DcCAMTA6 promotes γ-aminobutyric acid (GABA) accumulation via regulating GABA shunt in fresh-cut carrots

Abstract

The potential regulatory mechanisms of 1 % calcium chloride (CaCl2) treatment on the γ-aminobutyric acid (GABA) accumulation of fresh-cut carrots were investigated. The results indicated that CaCl2 application enhanced the contents of GABA shunt-related substances and activated the GABA shunt via enhancing the activities and genes expression of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T). Moreover, CaCl2 treatment enhanced the levels of [Ca2+]cyt, as well as up-regulated the expression of DcCaM7 and DcCAMTA6. However, the EGTA, a Ca2+ chelating agent treatment had the opposite effect on both GABA shunt and calcium signal-related components. Importantly, DcCaM7 interacted with DcCAMTA6 through an IQ motif, forming a heterodimer that facilitated the enhanced transcriptional regulation of DcCAMTA6 in the expression of DcGAD and DcGABA-T genes. Therefore, our results indicated that DcCaM7-DcCAMTA6 complex positively regulate GABA accumulation by activating GABA shunt in fresh-cut carrots.