Metabolic responses of Thellungiella halophila/salsuginea to biotic and abiotic stresses: Metabolite profiles and quantitative analyses

The metabolite profiles of the model crucifer Thellungiella salsuginea (salt cress) ecotype Shandong subjected to various biotic and abiotic stresses were analyzed using HPLC-DAD-ESI-MS. Two different cruciferous microbial pathogens, Albugo candida, a biotrophic oomycete, and Leptosphaeria maculans, a necrotrophic fungus, elicited formation of the phytoalexins wasalexins A and B without causing visual damage on inoculated leaves. Analyses of non-polar and polar metabolites led to elucidation of the chemical structures of five metabolites: 4'-O-(E)-sinapoyl-7-methoxyisovitexin-2 ''-O-beta-D-glucopyranoside, 4'-O-(E)-sinapoylisovitexin-2 ''-O-beta-D-glucopyranoside, 4-O-beta-D-glucopyranosyl-7-hydroxymatairesinol, 5'-O-beta-D-glucopyranosyldihydroneoascorbigen and 3-O-beta-D-glucopyranosylthiane. 3-O-beta-D-glucopyrano-sylthiane, an unique metabolite for which we suggest the name glucosalsuginin, is proposed to derive from the glucosinolate glucoberteroin. In addition, the identification of a broad range of polar metabolites identical to those of other crucifers was carried out. Quantification of several metabolites over a period of eight days showed that concentrations of the polar phytoanticipin 4-methoxyglucobrassicin increased substantially in leaves irradiated with UV light (lambda(max) 254 nm) relative to control leaves, but not in leaves subjected to other stresses. (C) 2009 Elsevier Ltd. All rights reserved.