Metabolic movement upon abscisic acid and salicylic acid combined treatments

Plant hormones are known to play important roles for maintenance of internal conditions under various environmental stresses. Recent studies revealed that there is a significant cross-talk between abiotic and biotic stress responses. To understand such complex mechanisms, comprehensive analyses at multiple levels are required. In this study, to examine the dynamic interactions between plant hormone responses, we analyzed the metabolic movements of Arabidopsis thaliana cultured cells during hormone treatments by NMR metabolic profiling. First, we verified the effect of plant hormone treatments on intracellular metabolites, and detected that the abscisic acid (ABA), salicylic acid (SA), auxin, and brassinosteroid treatment caused metabolic changes. Secondly, since SA and ABA act antagonistically against each other, we monitored dynamic metabolic movements during ABA and SA combined treatments. The response to ABA-only treatment suggested that sugars and amino acids significantly increased. Although SA alone caused fewer metabolic changes, SA caused remarkable metabolic changes when applied in combination with ABA. In addition, our NMR data implied that salicylate glucoside (SAG), which is major metabolite converted from SA, significantly increased in the SA-only treatment but decreased with ABA in a dose dependent manner. These results suggest that ABA and SA cross-talk at the metabolite level in a complicate manner and that the combination of various conditions will provide us with a holistic view of plant stress response mechanisms.