Although two genes responsive to GABA were characterized previously in plants (Kathiresan et al 1997), a comprehensive study in reproductive and vegetative tissues has not been performed. Consequently, genes that mediate GABA response in plants remain unknown. We therefore used microarrays to survey the genome, identifying genes modulated in response to GABA in reproductive tissues. Flowers were collected as described in the protocols section for RNA extraction and hybridization on Affymetrix ATH1 Genechip microarrays. Gene expression in wild-type and pop2-1 mutant flowers containing high levels of endogenous GABA were compared.