@article{oai:tsukuba.repo.nii.ac.jp:00040497,
 author = {千昭, 千昭 and 有泉, 亨 and 江面, 浩 and Takayama, Mariko and Matsukura, Chiaki and Ariizumi, Tohru and Ezura, Hiroshi},
 issue = {1},
 journal = {Plant cell reports},
 month = {Jan},
 note = {γ-Aminobutyric acid (GABA) is a ubiquitous non-protein amino acid with several health-promoting benefits. In many plants including tomato, GABA is synthesized via decarboxylation of glutamate in a reaction catalyzed by glutamate decarboxylase (GAD), which generally contains a C-terminal autoinhibitory domain. We previously generated transgenic tomato plants in which tomato GAD3 (SlGAD3) was expressed using the 35S promoter/NOS terminator expression cassette (35S-SlGAD3-NOS), yielding a four- to fivefold increase in GABA levels in red-ripe fruits compared to the control. In this study, to further increase GABA accumulation in tomato fruits, we expressed SlGAD3 with (SlGAD3OX) or without (SlGAD3ΔCOX) a putative autoinhibitory domain in tomato using the fruit ripening-specific E8 promoter and the Arabidopsis heat shock protein 18.2 (HSP) terminator. Although the GABA levels in SlGAD3OX fruits were equivalent to those in 35S-SlGAD3-NOS fruits, GABA levels in SlGAD3ΔCOX fruits increased by 11- to 18-fold compared to control plants, indicating that removing the autoinhibitory domain increases GABA biosynthesis activity. Furthermore, the increased GABA levels were accompanied by a drastic reduction in glutamate and aspartate levels, indicating that enhanced GABA biosynthesis affects amino acid metabolism in ripe-fruits. Moreover, SlGAD3ΔCOX fruits exhibited an orange-ripe phenotype, which was associated with reduced levels of both carotenoid and mRNA transcripts of ethylene-responsive carotenogenic genes, suggesting that over activation of GAD influences ethylene sensitivity. Our strategy utilizing the E8 promoter and HSP terminator expression cassette, together with SlGAD3 C-terminal deletion, would facilitate the production of tomato fruits with increased GABA levels.},
 pages = {103--116},
 title = {Activating glutamate decarboxylase activity by removing the autoinhibitory domain leads to hyper γ-aminobutyric acid (GABA) accumulation in tomato fruit},
 volume = {36},
 year = {2017}
}