Regulation of Respiration and Fermentation to Control the Plant Internal Oxygen Concentration
Regulation of Respiration and Fermentation to Control the Plant Internal Oxygen Concentration
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DOI：
10.1104/pp.108.129288
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发表时间：
2009-02-01
期刊：
影响因子：
7.4
通讯作者：
Geigenberger, Peter
中科院分区：
文献类型：
--
作者：
Zabalza, Ana;Van Dongen, Joost T.;Geigenberger, Peter
即使当植物在最佳条件下生长时，植物内部的氧气浓度也会下降到远低于周围环境的水平。使用豌豆(豌豆)的根，我们展示了当氧气利用率下降时，顺应呼吸如何适应低氧来节省氧气。这些数据不能简单地用氧作为底物来解释，而是表明存在一种调节机制，因为启动适应性反应的氧浓度与实际呼吸频率无关。在适应性反应中可以看出两个阶段：呼吸的初始线性下降之后是非线性抑制，其中呼吸速率随着氧气可获得性的降低而逐渐下降的速度更快。与细胞色素c途径不同，交替氧化酶途径的抑制只显示了适应性反应的线性成分。向根部补饲丙酮酸会导致耗氧率增加，最终导致缺氧。进一步研究了平衡组织中丙酮酸体内可利用性的重要性。利用不同的拟南芥乙醇脱氢酶基因敲除系，研究表明，即使在有氧条件下，酒精发酵也对组织中丙酮酸的水平起着重要的控制作用。有趣的是，酒精发酵似乎主要是由组织能量状态的下降而不是低氧浓度引起的，这表明感知能量状态是优化植物新陈代谢以适应氧气供应变化的重要组成部分。
Plant internal oxygen concentrations can drop well below ambient even when the plant grows under optimal conditions. Using pea (Pisum sativum) roots, we show how amenable respiration adapts to hypoxia to save oxygen when the oxygen availability decreases. The data cannot simply be explained by oxygen being limiting as substrate but indicate the existence of a regulatory mechanism, because the oxygen concentration at which the adaptive response is initiated is independent of the actual respiratory rate. Two phases can be discerned during the adaptive reaction: an initial linear decline of respiration is followed by a nonlinear inhibition in which the respiratory rate decreased progressively faster upon decreasing oxygen availability. In contrast to the cytochrome c pathway, the inhibition of the alternative oxidase pathway shows only the linear component of the adaptive response. Feeding pyruvate to the roots led to an increase of the oxygen consumption rate, which ultimately led to anoxia. The importance of balancing the in vivo pyruvate availability in the tissue was further investigated. Using various alcohol dehydrogenase knockout lines of Arabidopsis (Arabidopsis thaliana), it was shown that even under aerobic conditions, alcohol fermentation plays an important role in the control of the level of pyruvate in the tissue. Interestingly, alcohol fermentation appeared to be primarily induced by a drop in the energy status of the tissue rather than by a low oxygen concentration, indicating that sensing the energy status is an important component of optimizing plant metabolism to changes in the oxygen availability.