The roles of redox processes in pea nodule development and senescence
The roles of redox processes in pea nodule development and senescence
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DOI：
10.1111/j.1365-3040.2005.01376.x
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发表时间：
2005-10-01
影响因子：
7.3
通讯作者：
Foyer, CH
中科院分区：
文献类型：
--
作者：
Groten, K;Vanacker, H;Foyer, CH
结节衰老是由发育和环境因素引发的。它是通过复杂但特征不明确的遗传控制精心策划的，涉及活性氧（ROS）和抗氧化剂内源水平的变化。为了阐明这种氧化还原控制机制在豌豆根瘤衰老中的重要性，对接种了商业根瘤菌菌株（豆科根瘤菌 bv. viciae）的商业豌豆品种（Pisum sativum cv. Phoenix）在整个根瘤发育过程中的氧化还原代谢物进行了分析。尽管固氮酶活性与根瘤抗坏血酸和谷胱甘肽含量之间存在很强的正相关性，但在根瘤衰老过程中这些代谢物的逐渐损失并不伴随根瘤超氧化物或过氧化氢的增加。这些氧化剂仅在根瘤分生组织和皮层组织中检测到，并且超氧化物或过氧化氢的丰度随着年龄的增长而急剧下降。没有发现结节衰老过程中程序性细胞死亡的证据，并且蛋白质羰基在整个结节发育过程中或多或少是恒定的。豌豆根瘤似乎没有从头合成抗坏血酸的能力。在结节中无法检测到催化抗坏血酸合成最后一步的 L-半乳糖-1, 4-内酯脱氢酶 (GalLDH)。此外，当用底物L-半乳糖-1、4-内酯或L-古洛糖酸内酯渗透时，抗坏血酸不会积累。这些数据表明，在植物中履行公认的信号功能的活性氧、抗坏血酸和谷胱甘肽在根瘤发育过程中以受调控的方式下降。这并不一定会导致氧化应激，而是表明氧化还原相关代谢物串扰发生了与发育相关的变化，从而支撑了发育和衰老过程。
Nodule senescence is triggered by developmental and environmental cues. It is orchestrated through complex but poorly characterized genetic controls that involve changes in the endogenous levels of reactive oxygen species (ROS) and antioxidants. To elucidate the importance of such redox control mechanisms in pea root nodule senescence, redox metabolites were analysed throughout nodule development in a commercial pea variety (Pisum sativum cv. Phoenix) inoculated with a commercial rhizobial strain (Rhizobium leguminosarum bv. viciae). Although a strong positive correlation between nitrogenase activity and nodule ascorbate and glutathione contents was observed, the progressive loss of these metabolites during nodule senescence was not accompanied by an increase in nodule superoxide or hydrogen peroxide. These oxidants were only detected in nodule meristem and cortex tissues, and the abundance of superoxide or hydrogen peroxide strongly declined with age. No evidence could be found of programmed cell death in nodule senescence and the protein carbonyl groups were more or less constant throughout nodule development. Pea nodules appear to have little capacity to synthesize ascorbate de novo. L-galactono-1, 4-lactone dehydrogenase (GalLDH), which catalyses the last step of ascorbate synthesis could not be detected in nodules. Moreover, when infiltrated with the substrates L-galactono-1, 4-lactone or L-gulonolactone, ascorbate did not accumulate. These data suggest that ROS, ascorbate and glutathione, which fulfil well recognized, signalling functions in plants, decline in a regulated manner during nodule development. This does not necessarily cause oxidative stress but rather indicates a development-related shift in redox-linked metabolite cross-talk that underpins the development and aging processes.