1. scpl17-1 wild type SCPC17:SCPL17 scpl17-1 scpl17-2 CsMV:SCPL17 scpl17-2 Retention time (min) Absorbance at 229 nm Absorbance at 330 nm 3BZO 4BZO4SIN 3SIN scpl17-1 wild type SCPC17:SCPL17 scpl17-1 scpl17-2 CsMV:SCPL17 scpl17-2 IS (a) (b) Figure S1. Complementation analyses of scpl17 mutant seeds. Two independent scpl17 mutants were transformed with the const ructs overexpressing SCPL17 under endogenous SCPL17 promoter and CsMV promoter. Total GSL profiles at 229 nm (a) and SnGS L profiles at 330 nm (b) are extracted from the same diode array dataset and the y-axis of each chromatogram is scaled equivalen tly. IS, internal standard sinigrin.

2. Absorbance at 229 nm Absorbance at 330 nm sng2-2 wild type CsMV:SCT sng2-2 3BZO 4BZO sng2-2 wild type CsMV:SCT sng2-2 Figure S2. Complementation analyses of sng2-2 mutant seeds. The sng2-2 mutant was complemented with the construct overexpressing SCT under CsMV promoter. Total GSL profiles at 229 nm (a) and SnGSL profiles at 330 nm (b) are extracted from the same diode array dataset and the y-axis of each chromatogram is scaled equivalently. IS, internal standard sinigrin. 4SIN 3SIN Retention time (min) IS (a) (b)

3. Figure S3. Benzoate feeding into wild-type and bzo1-4 siliques. After 3 days, the amounts of benzoylglucose, benzoylcholine (A), OH-GSLs (B), and BzGSLs (C) were measured. - BA: siliques treated with DDW; + BA: siliques treated with 1mM benzoate. *, Student’s t-test, P < 0.05 vs. - BA. Mean±SD (n = 3). (a) (b) pmol mg tissue -1 nmol mg tissue -1 * * * (c) nmol mg tissue -1 * * * * *