Effect of Ethrel and AVG on auxin concentrations and the expression of selected auxin biosynthesis and GH3 genes in an ex planta experiment. IAA (A) and the IAA-amino acid conjugate, IAA-Asp, (B) were quantified by LC-MS/MS in ex planta pre-veraison Shiraz berries exposed to ReTain (125 mg L-1 AVG, 3% (w/v) sucrose), Ethrel (72 mg L-1 ethephon, 3% (w/v) sucrose), or Control (3% (w/v) sucrose) conditions for the indicated periods of time. FW, fresh weight. (C) Using the same tissues the expression of TAR1-TAR4, YUC1, GH3-1 and GH3-2 was analysed by qRT-PCR. Control, dark grey bars; Ethrel, light grey bars; AVG, white bars. Bars represent means ± SE (n = 3) and are denoted by a different letter if the means for each time point differ significantly (p < 0.05) using one-way ANOVA followed by Duncan’s post hoc test.