Figure 3.

Phenylpropanoid Accumulation Is Limited by IAOx or an Aldoxime Derivative.

(A) Scheme of the indole glucosinolate biosynthesis pathway. The oxidation of Trp to IAOx is catalyzed by CYP79B2 and CYP79B3. CYP83B1/REF5 subsequently oxidizes IAOx to a product that spontaneously reacts to produce an S-alkylthiohydroximate. Further modifications, such as glucosylation and sulfation, give rise to the final indole glucosinolates.

(B) Desulfoglucosinolate content measured from rosette leaves of 3-week-old plants. Data represent mean ± sd (n = 4).

(C) Quantification by HPLC of sinapoylmalate in leaves of the wild type, ref5-1, cyp79b2 cyp79b3 double mutant, ref5-1 cyp79b2 cyp79b3 triple mutant, and yuc6-1D, an auxin accumulation mutant. Data represent mean ± sd (n = 5). * and ** indicate P < 0.05 and P < 0.01 compared with the wild type, respectively. * and ** indicate P < 0.05 and P < 0.01 by a two-tailed Student’s t test compared with the wild type, respectively.

(D) Impact of overexpression of CYP79B2 on levels of sinapoylmalate. Sinapoylmalate content in wild-type (open circle) and transgenic plants overexpressing CYP79B2 (closed circle) is shown.