OXIDATIVE STRESS AND MITOCHONDRIAL DYSFUNCTION IN FROST-EXPOSED VALENCIA ORANGE FRUIT

FALCONE FERREYRA, M. LORENA; PEROTTI, VALERIA; GARRÁN, SERGIO; ANDERSON, PERLA C.; VÁZQUEZ, DANIEL; PODESTÁ, FLORENCIO E.

Iguazu, Misiones

Congreso; · XL Reunión anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2004

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Low temperatures cause severe damage in Valencia orange fruit (Citrus sinensis L. Osbeck) resulting in low-quality fruits. It has been reported that oxidative stress is induced by cold in citrus fruits, therefore our objectives were to analyze the antioxidant enzymes and the mitochondrial functionality. Total protein content on the fresh weight basis showed a sharp decrease (37%) in frozen fruits. Induction of APX, CAT and POD was observed in native gels by activity staining, while a Mn-SOD slightly dismissed. Measurements of MDH activity and reduction of exogen cytocrome c in isolated mitochondria indicated lower integrity of them in frozen fruits. Moreover, respiration rate of whole fruit was significatively reduced by 30%, whereas the flavedo showed a more pronounced descent (53%). Chemical and internal quality parameters were also affected, volatile compounds, l-malate and titrable acidity increased, while the percentage of juice, maturity index showed a marked decrease in frozen fruits. In addition, whole fruit weight did not any significant variation. In contrast, fruits without peel lost weight by 26%, whereas the weight of the flavedo was 1.4-fold higher in frozen fruits. In conclusion, the results suggest that cold imposes oxidative stress in oranges, it would be initiated in the mitochondria resulting in less active and functional ones. In this way, oxidative stress could be involved in cold-induced damage of orange fruits.