A detailed description of GABA metabolism and the genes involved in tomato; and the different approaches used to replace the classical breeding. These information is essential for manipulating GABA levels in fruit.

To serve as guidelines for other crops first the metabolic pathway of GABA in the tissue of interest should be known because in tomato the GABA content in the leaves is different from the fruit and correlated with the chloroplastic electron transport rate (https://doi.org/10.1007/s11306-019-1503-8). Moreover, influence of the cultivation conditions on GABA levels should be clearly defined. In tomato the gaba content is also dependent of the cultivated tomato variety in the same field condition as revealed by previous studies (doi:10.1093/jxb/erp086; https://doi.org/10.1007/s00425-019-03274-4). Increased GABA content does lead to decrease Glutamate content? WHERE does GABA accumulate?