Activation of γ-aminobutyrate production by chloroplastic H(2)O(2) is associated with the oxidative stress response.

We isolated an Arabidopsis knockout line lacking glutamate decarboxylase 1 (GAD1), one that produced γ-aminobutyrate (GABA), as an oxidative stress-insensitive mutant, and found that chloroplastic H(2)O(2) enhances GAD1 expression and GABA levels. This suggests a possible relationship between GABA metabolism and the chloroplastic H(2)O(2)-mediated stress response.