Selective enhancement of alternative path capacity in plant storage organs in response to ethylene plus oxygen: a comparative study.

The respiration rise in bulky storage organs induced by ethylene plus pure O(2) is accompanied by an increase in the CN-resistant respiration, or alternative path. Whereas a lesser respiratory stimulation in response to ethylene is demonstrable in air and increased by peeling, ethylene-induced alternative path development depends on the synergistic effect of pure O(2), with or without peeling. The effect of ethylene plus O(2) is evident, whether untreated parent organs yield CN-sensitive or CN-resistant fresh slices. Alternative path capacity and maximal cytochrome oxidase-mediated electron transport have been separately estimated. Ethylene plus O(2) selectively enhances the alternative path. It is proposed that the gross rise in respiration evoked by ethylene is implemented by a system with an O(2) requirement much higher than that of cytochrome oxidase, while the ethylene-induced development of the alternative path depends on a system of still higher O(2) requirement.