Zeng S., Tjepkema J. D.
Department of Plant Biology and Pathology, University of Maine, Orono, Maine 04469-5722.
Plant Physiol. 1995 Apr;107(4):1269-1275. doi: 10.1104/pp.107.4.1269.
Rates of C2H2 reduction and CO2 evolution by nodules were measured in a flowthrough system using intact plants of Myrica gale L. Both activities increased linearly with increasing partial pressure of O2 (pO2) up to 18 kPa. The linear relationship between CO2 evolution and pO2 at pO2 values between 6 and 18 kPa suggests that the diffusion barrier has a constant resistance. The lack of a variable resistance was further supported by sustained increases and decreases in nodule activities in response to changes in pO2 in the range of 6 to 20 kPa O2. When pO2 was increased above 20 kPa, C2H2 reduction and CO2 evolution continually declined with time. These results confirm that the diffusion barrier in nodules of M. gale is not variable in response to changes in pO2. The effect of temperature was examined at 8 and 20 kPa O2. Rates of C2H2 reduction and CO2 evolution increased with increasing temperature from 10 to 30[deg]C at both pO2 values. These results indicate that the diffusion resistance of the barrier changes as temperature changes, with the resistance decreasing as temperature increases.
使用杨梅完整植株，在流通系统中测定了根瘤还原乙炔（C₂H₂）和释放二氧化碳（CO₂）的速率。在氧气分压（pO₂）高达18 kPa时，这两种活性均随pO₂的增加呈线性增加。在6至18 kPa的pO₂值下，CO₂释放与pO₂之间的线性关系表明扩散屏障具有恒定阻力。在6至20 kPa O₂范围内，根瘤活性随pO₂的变化持续增加和降低，这进一步支持了不存在可变阻力的观点。当pO₂增加到20 kPa以上时，C₂H₂还原和CO₂释放随时间持续下降。这些结果证实，杨梅根瘤中的扩散屏障不会随pO₂的变化而变化。在8 kPa和20 kPa O₂下研究了温度的影响。在这两个pO₂值下，从10℃到30℃，C₂H₂还原和CO₂释放速率均随温度升高而增加。这些结果表明，屏障的扩散阻力随温度变化，阻力随温度升高而降低。
