Cyanide-insensitive respiration in wheat: cultivar differences and effects of temperature, carbon dioxide, and oxygen

Publisher Website
Google Scholar
Abstract
The cyanide-insensitive respiration of the mitochondrial fraction isolated from etiolated coleoptiles of four cultivars of wheat has been studied under a variety of conditions. Cultivar differences were observed in the apparent capacity of the CN-insensitive pathway ranging from 8 to 35% of the observed state 3 respiration rate. Although Arrhenius plots of the state 3 and state 4 rates were relatively linear from 2.5 to 30 °C, the CN-insensitive oxygen uptake exhibited a distinct maximum rate at about 17.5 °C. Germination of the wheat in the presence of high concentrations of CO2 (15–25%) resulted in a dramatic increase in the capacity of the CN-insensitive pathway. Germination in 100% O2 appeared to have little effect on either the cytochrome or CN-insensitive electron-transport pathways. However, oxygen did exert a synergistic effect with CO2 since germination in 25% CO2 in oxygen yielded mitochondria with about twice the CN-insensitive capacity of wheat germinated in 25% CO2 in air.