Abstract
Upon treatment of in vitro cultured cells of rice with elicitor of Magnaporthe grisea induced ROS production, expression of several defense genes, and cell death. To elucidate effects of elicitor on rice calli, we investigated the several metabolite levels using capillary electrophoresis-mass spectrometry (CE/MS). After elicitor treatment, metabolites of TCA cycle were decreased, while γ-aminobutyrate (GABA) was strongly increased. We therefore compared activities of enzymes engaged in GABA shunt. The activity of glutamate decarboxylase, a GABA-synthetic enzyme, was decreased at 8 hours after the treatment. However, the activity of GABA aminotransferase, GABA-degrading enzyme, was decreased by 28% of control at 4 hours after the treatment. These results suggested that the accumulation of GABA was caused by downregulation of GABA degradation. The inactivation of GABA transaminase by elicitor may be important for the commitment of elicitor induced cell death.
