The Respiratory Pattern in the Tomato Fruit and its Alteration by Infiltration with Various Chemicals.

\V;hether the toimato fruit is left to ripen on or off the plant, a marked increase in its respiratory rate knowni as the climacteric is observed as it passes from the mature green to the ripe stage (4, 7, 15, 19). A number of hypotheses have been advanced to exllain this climacteric rise in respiration (3, 10). It has been suggested that the climacteric rise is caused by increased utilization of ATP or endogenous unicoupling of oxidative phosphorylation (16). At present there is no data indicative of uncoupling in situ, and tightly coupled mitochondria have been isolated from avocado fruits at the climacteric peak (20). Increased utilization of ATP could result from the onset of energy requiring processes such as protein synthesis (8, 19). Increased turnover of ATP may be related to changes in mitochondrial permeability. Lyons and Pratt ( 12) reported that ethylene caused swelling in isolated mitochondria. Thev suggested that ethylene may increase the permeability of mitochonldria within intact fruits. allowing more rapid movemenit of adeninle nucleotides througlh mitoclhonldrial memiibranies. MIost of the hypotheses about respiratory increases during the climacteric and the controllinig mechanismis of respiration have been derived from studies otn tissue slices and mlitochondlrial preparations rather than on whole fruit (17, 18, 20). Such inferences would hold true onily if the conditions in the tissue slices and mitochondrial preparations are the same as those in the whole fruit. The respiratory patterns of whole tomato, tissue slices, anid mitochonidrial preparations were compared over a wide range of fruit maturity. The climacteric rise in respiration as well as alterations of the normal respiratory pattern in the fruit brought about by various chemicals was investigated.