Ripening and in vitro retention of respiratory control by avocado and pear mitochondria

The retention of respiratory control (“survival”) by mitochondria held at 25 C was studied in relation to the ripening of two varieties of avocado (Persea americana Mill. var. `Fuerte' and `Hass') and one variety of pear (Pyrus communis. L. var. `Bartlett') fruit. The survival of avocado mitochondria increased from 8 to 10 hours when isolated from unripe, preclimacteric fruit, to 48 hours when isolated from fully ripe, postclimacteric fruits. Although rates of α-ketoglutarate oxidation, respiratory control, and ADP/O decreased somewhat in the postclimacteric phase, survival per se was not affected. Pear mitochondria survived for more than 30 hours regardless of the physiological age of the source.