RESPIRATORY ACTIVITY IN ISOLATED MITOCHONDRIA FROM THE PULP OF UENF/CALIMAN01 AND TAINUNG01 PAPAYA IN POSTHARVEST FRUIT CONSERVATION

This study had the object of comparing the respiratory activity in isolated mitochondria and the physical and chemical attributes of the pulp of two papaya hybrids, UENF/Caliman01 and Tainung01, during fruit ripening. The fruit ripening did not show significant differences between the genotypes with regard to lightness (L), chroma (C), and hue angle of the skin. The loss of mass (LM) and the firmness of fruit (FF) and mesocarp (FM) differed between the genotypes, with FF and FM decreasing with time after harvest, while LM rose over the same period. The respiratory activity in the isolated mitochondria revealed differences between the genotypes with respect to total respiration (TR), being higher and with negative time-correlation function in Tainung01 and constant in UC01 during fruit ripening. During this period the participation of alternative oxidase (AOX) pathway was crescent, against the decreasing participation of cytochrome c oxidase (COX) pathway in both hybrids was verified, indicating an increasing uncoupling of the mitochondria, which may be associated with the rapid biochemical transformations that cause the senescence of the organ. From these results, investigating genetic materials with lower AOX activity or ways of minimizing the respiratory activity in postharvest fruit is suggested. The AOX presented the high positive correlation with LM and negative with FF and FM while the inverse was observed for COX. The TR presented positive correlation only with the FM. The correlations indicated the viability of estimated respiratory activity through simpler analyses such as LM, FF, and FM, thus facilitating studies in the area.

Ripening; Carica papaya L.; cytochrome c oxidase; alternative oxidase; respiration