Effects of selenite selenium on respiration in maize roots

Summary

One-centimeter root-tip segments submerged in phosphate buffer solutions (pH 4.5 to 5.5) were treated with Na₂SeO₃ concentrations ranging from 0.005 to 10.0 mM. Uptake of O₂ and CO₂ output were measured manometrically. Segments exposed aerobically to 1.0 and 10.0 mM selenite for several hours exhibited a considerable decrease in O₂ input, particularly at the higher concentration. In contrast, CO₂ output was greatly accelerated by selenite concentrations of 2.5 to 10.0 mM. Consequently respiratory quotient values were large for these high concentrations. Under conditions of marked O₂ deficiency, CO₂ output was appreciably decreased regardless of the presence or absence of selenite. Use of Se⁷⁵ showed that the gas output with selenite did not include a volatile selenium compound. A striking parallel was indicated between concentration effects of selenite and published arsenite effects on aerobic fermentation. This was confirmed by including both selenite and arsenite treatments in the same experiments. re]19730427