biostudies-literaturePiechatzek AUniversity of Adelaide6856-6871https://www.ebi.ac.uk/biostudies/studies/S-EPMC11565201biostudies-literatureUnknown75(21)Optimal stomatal regulation is important for plant adaptation to changing environmental conditions and for maintaining crop yield. The guard cell signal γ-aminobutyric acid (GABA) is produced from glutamate by glutamate decarboxylase (GAD) during a reaction that generates CO2 as a by-product. Here, we investigated a putative connection between GABA signalling and the more clearly defined CO2 signalling pathway in guard cells. The GABA-deficient mutant Arabidopsis lines gad2-1, gad2-2, and gad1/2/4/5 were examined for stomatal sensitivity to various CO2 concentrations. Our findings show a phenotypical discrepancy between the allelic mutant lines gad2-1 and gad2-2-a weakened CO2 response in gad2-1 (GABI_474_E05) in contrast to a wild-type response in gad2-2 (SALK_028819) and gad1/2/4/5. ThroJournal of experimental botanyGABA does not regulate stomatal CO2 signalling in Arabidopsis.PMC11565201CE230100015Ache PDittrich MHerrmann JFeng XMuller THurgobin BPiechatzek AKromdijk JLewsey MSai NHedrich RXu BYi CGilliham MfalseGABA does not regulate stomatal CO2 signalling in Arabidopsis.Optimal stomatal regulation is important for plant adaptation to changing environmental conditions and for maintaining crop yield. The guard cell signal γ-aminobutyric acid (GABA) is produced from glutamate by glutamate decarboxylase (GAD) during a reaction that generates CO2 as a by-product. Here, we investigated a putative connection between GABA signalling and the more clearly defined CO2 signalling pathway in guard cells. The GABA-deficient mutant Arabidopsis lines gad2-1, gad2-2, and gad1/2/4/5 were examined for stomatal sensitivity to various CO2 concentrations. Our findings show a phenotypical discrepancy between the allelic mutant lines gad2-1 and gad2-2-a weakened CO2 response in gad2-1 (GABI_474_E05) in contrast to a wild-type response in gad2-2 (SALK_028819) and gad1/2/4/5. Thro2024-01-01T00:00:00Z2024 Nov2026-07-16T21:47:33.931Z2025-04-05T18:41:31.844ZS-EPMC115652013862815510.1093/jxb/erae168