CONICET | Buscador de Institutos y Recursos Humanos

Gutamate content in tomato fruits increases dramatically during the ripening process, becoming the most abundant free amino acid of ripe tomato fruits. Glutamate is involved in conferring the genuine tomato flavour. Potential sources of this glutamate increase are the proteolytic turnover of endogenous peptides, the novo synthesis and the import from the leaves. In this work glutamate dehydrogenase (GDH) one of the enzymes that could be involved in the glutamate raise was studied. GDH activity increases during the fruit ripening along with the content of free glutamate. This enzyme catalizes the reversible amination of 2-oxoglutarate to form glutamate. During this work, gdh genes encoding the α- and β-subunits of tomato GDH were identified and characterized at the level of their genomic organization and their expression pattern in different organs, particularly in ripening fruits of tomato. This was done under normal growing conditions, and in the presence of glutamate and molecules like salicylic acid (SA) and NaCl, which are related to biotic and abiotic stresses, respectively. Additionally, distribution of enzyme activities and polypeptides of the α- and β-subunits of the hexameric GDH in different Micro-Tom organs were analysed. Also, to clarify the role of GDH in the glutamate metabolism during the fruit ripening, plants with reduced GDH levels were generated by artificial microRNA (amiRNA). Although the metabolism of these plants is still under study some preliminary results about metabolite levels and enzymatic activities will be shown. Taken together, these data provide novel information about the environmental and physiological control and role of GDH in tomato fruits