Reply: Complexity in Camalexin Biosynthesis

摘要

In Su et al. (2011), we reported that accumulation of multiple glutathione S-transferases (GSTs), elevation of GST activity, and consumption of GSH coincides with camalexin production;GSTF6 overexpression increased and GSTF6 knockout reduced camalexin production; Arabidopsis thaliana GSTF6 expressed in yeast cells catalyzed GSH(IAN) formation; GSH(IAN), (IAN)CysGly, and γGluCys(IAN) are intermediates within the camalexin biosynthetic pathway; and, finally, γ-glutamyl transpeptidases (GGTs) and phytochelatin synthase are involved in the catabolism of GSH(IAN). Based on these data and the expression patterns of these genes, we suggest that (1) GSH is the Cys derivative used during camalexin biosynthesis, (2) the conjugation of GSH with IAN is catalyzed by GSTF6, and (3) GGTs and phytochelatin synthase are involved in camalexin biosynthesis. The Letter to the Editor by Mldrup et al. (2013) and another report by the same group (Geu-Flores et al., 2011) argue that γ-glutamyl peptidases (GGPs), and not GGTs, are the γ-glutamyl cleaving enzymes in the camalexin pathway in Arabidopsis.