Transgenic tomato plants that overexpress a gene for NADH-dependent glutamate dehydrogenase (legdh1)

Tomato plants were transformed with a plasmid that included a legdh1 gene for NADH-dependent glutamate dehydrogenase (NADH-GDH) from Lycopersicon esculentum Mill. coupled, in the sense orientation, with the constitutively active 35S promoter from cauliflower mosaic virus. Three independent transformants were obtained. In these transgenic lines, high-level expression of legdh1 mRNA was detected in the leaves, and the NADH-GDH activity in the leaves of the transgenic plants was approximately twice that in the leaves of the non-transgenic plant. In the transgenic tomato fruits examined for six successive weeks after flowering, the levels of total free amino acids were higher (2. 1- to 2.3-fold) than those in the controls. In particular, the level of glutamate was about twice that in the control fruits.