Abstract
A large amount of γ-aminobutyric acid (GABA) was accumulated in the tomato (Solanum lycopersicum) fruits before breaker, and was rapidly catabolized after breaker. We previously screened GABA-rich tomato cultivar 'DG03-9'which did not show rapid GABA catabolism after breaker. Although GABA rapid catabolism in fruits is well known, the mechanisms are not clear. In order to clarify this mechanisms, we carried out comparative studies of Micro-Tom and DG03-9 fruits in gene expression levels, protein levels and enzyme activity levels of GABA biosynthesis and catabolism-related enzymes. We found strong correlation between GABA contents and enzyme activity of α-ketoglutarate-dependent GABA transaminase (GABA-TK), which is the major GABA-transaminase form in animals, and seems to be a minor form in plant. Our results suggested that GABA-TK play crucial roles in GABA catabolism in the tomato fruits.
