THE ROLE OF DARK CARBON-DIOXIDE FIXATION IN ROOT-NODULES OF SOYBEAN
THE ROLE OF DARK CARBON-DIOXIDE FIXATION IN ROOT-NODULES OF SOYBEAN
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DOI：
10.1104/pp.81.1.200
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发表时间：
1986-05-01
期刊：
影响因子：
7.4
通讯作者：
CANVIN, DT
中科院分区：
文献类型：
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作者：
KING, BJ;LAYZELL, DB;CANVIN, DT
在完整的大豆植株的根瘤中研究了黑暗二氧化碳固定的程度和作用(Harosoy 63。日本根瘤菌菌株USDA 16)。根据饱和条件下14CO2脉冲饲喂2分钟，根瘤暗CO2固定的速度估计为每克干重每小时102微摩尔。这相当于根瘤净呼吸的14%。据估计，生长和出口过程中有机和氨基酸合成只需要18%的二氧化碳固定。固定标签的大部分(75%-92%)在60分钟内以二氧化碳的形式释放。脉冲追逐实验中的标记模式与磷酸烯醇式丙酮酸羧基酶固定CO2的模式一致。在追逐过程中，标记损失最大的是有机酸。Ar：O2(80：20)暴露对暗CO2固定没有影响，而O2：CO2(95：5)暴露则有54%的抑制。从这些结果可以得出结论，大豆中至少66%的暗固定CO2可能与有机酸的产生有关，当有机酸被氧化时，能够提供至少48%的ATP等价物来支持固氮酶活性。
The magnitude and role of dark CO2 fixation were examined in nodules of intact soybean plants (Harosoy 63 .times. Rhizobium japonicum strain USDA 16). The estimated rate of nodule dark CO2 fixation, based on a 2 minute pulse-feed with 14CO2 under saturating conditions, was 102 micromoles per gram dry weight per hour. This was equivalent to 14% of net nodule respiration. Only 18% of this CO2 fixation was estimated to be required for organic and amino acid synthesis for growth and export processes. The major portion (75-92%) of fixed label was released as CO2 within 60 minutes. The labeling pattern during pulse-chase experiments was consistent with CO2 fixation by phosphoenolpyruvate carboxylase. During the chase, the greatest loss of label occurred in organic acids. Exposure of nodulated roots to Ar:O2 (80:20) did not affect dark CO2 fixation, while exposure to O2:CO2 (95:5) resulted in 54% inhibition. From these results, it was concluded that at least 66% of dark CO2 fixation in soybean may be involved with the production of organic acids, which when oxidized would be capable of providing at least 48% of the requirement for ATP equivalents to support nitrogenase activity.