Acclimation of leaf respiratory properties in Alocasia odora following reciprocal transfers of plants between high- and low-light environments

Acclimation of respiration to the light environments is important for a plant's carbon balance. Respiratory rates of mature leaves of Alocasia odora, a typical shade-tolerant species, were measured during the night for 14 d after reciprocal transfers between high- (330 mu mol m(-2) s(-1)) and low-light (20 mu mol m(-2) s(-1)) environments. Following the transfer, both the rate Of CO2 efflux and that Of O-2 uptake of A. odora leaves adjusted to the new light environments. The O-2-uptake rates changed more slowly than the CO2-efflux rates under the new environments. Leaf mass per area also changed after the transfer. We analysed whether substrate availability or ATP-consumption rates influence the respiratory acclimation. Since the addition of sucrose to leaf segments did not influence the O-2-uptake rates, the change of respiratory substrate availability was not responsible for the respiratory acclimation. The addition of an uncoupler induced increases in the O-2-uptake rates, and the degree of enhancement significantly decreased after the transfer from low to high irradiance. Thus, the change in ATP-consumption rates was responsible for the changes in respiratory rates in the plants transferred from low to high light. Potential rates of O-2 uptake, as measured in the presence of both the substrate and the uncoupler, changed after the transfer, and strongly correlated with the O-2-uptake rates, irrespective of the directions of transfer (r = 0.961). There was a strong correlation between maximal activities of NAD-isocitrate dehydrogenase and the potential rates Of O-2 uptake (r = 0.933), but a weaker correlation between those of cytochrome c oxidase and the potential rates (r = 0.689). These data indicate that the changes of fight environments altered the respiratory rates via the change of the respiratory ATP demand, and that the altered rates of respiration will induce the changes of the respiratory capacities.