Regulation of O2 concentration in soybean nodules observed by in Situ spectroscopic measurement of leghemoglobin oxygenation

Regulation of O2 concentration in soybean nodules observed by in Situ spectroscopic measurement of leghemoglobin oxygenation

1988

A:PS

A fiber optic spectrophotometric system was used to monitor the in vivo oxygenation of leghemoglobin in intact, attached soybean root nodules (Glycine max L. Merr. X USDA 16 Bradyrhizobium japonicum) which were flattened during development by growth in narrow, glass-walled cuvettes. When equilibrated at an external p02 of 20 kilopascals, leghemoglobin was 36.6 :: 5.4% oxygenated, a value estimated to represent an infected cell O2 concentration of 21.5 nanomolar. Increasing the external p02 from 20 to 2S kilopascals caused a rapid increase in leghemoglobin oxygenation, followed by a recovery to the initial level, all within 7.5 minutes. At 2S kilopascals O2, the rates of 92 and CO2 evolution were similar to those at 20 kilopascals. Since respiration had not increased, the results support the proposal that nodules adapt to increased external p02 by regulating their resistance to O2 diffusion.

v.87(2):296-299, PLANT PHYSIOLOGY

Research > Published Articles