ON DE SHELF TOMATO RIPENING DISMINISHED GLUTAMATE CONTENT OF RED FRUITS

SORREQUIETA A; BOGGIO SB; VALLE EM

Mar del Plata. Buenos Aires. Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.

Free L-Glu is known as an enhancer of the natural flavour of the foods. It is also important in human diet as short chain of folate polyglutamate. Glu levels increased markedly in the pericarp of tomato fruits when the ripening process is carried out in-planta, while no changes were observed ex-planta. GABA (a non protein amino acid) levels decreased in the ripening transition of fruits kept both in- and ex-planta. We investigated the activity of GABA metabolism enzymes of tomato fruits under both ripening conditions. The activity of GABA transaminase (GABA-T), which catalyses the interconversion of GABA into Glu, increased only in in-planta ripening fruits. Succinic semialdehyde dehydrogenase (SSAdH) which catalyzes the oxidation of SSA (a GABA-T product) showed a decrease during ripening transition both, in- and ex-planta. Glutamate decarboxylase (GAD), which catalyzes the irreversible decarboxylation of Glu to GABA, also manifested a drop in its activity during in-planta ripening transition. The transcript levels of these enzymes were followed by Real Time-PCR showing different changes in mature green to red fruit transition. These results suggest a direct relationship between Glu and GABA levels through GABA-T activity and the importance of in-planta ripening in order to have high Glu content in ripe tomato fruits.