Improved photosynthetic performance during severe drought in Nicotiana tabacum overexpressing a nonenergy conserving respiratory electron sink
Improved photosynthetic performance during severe drought in Nicotiana tabacum overexpressing a nonenergy conserving respiratory electron sink
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DOI：
10.1111/nph.13479
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发表时间：
2015-10-01
期刊：
影响因子：
9.4
通讯作者：
Vanlerberghe, Greg C.
中科院分区：
文献类型：
--
作者：
Dahal, Keshav;Martyn, Greg D.;Vanlerberghe, Greg C.
叶绿体有办法管理过量的还原能力，但这些机制可能会受到 ATP 周转率的限制。替代氧化酶 (AOX) 是一种线粒体末端氧化酶，可解耦 ATP 合成中还原力的消耗。使用生理生化分析来比较烟草野生型 (WT) 植物与过度表达 AOX 的转基因品系在水分充足和干旱胁迫条件下的呼吸和光合作用。随着干旱的加剧 严重程度方面，相对于 WT，AOX 过表达可增加光下呼吸 (R-L)。 CO2 和光响应曲线表明，随着干旱严重程度的增加，相对于 WT，过度表达还改善了光合性能。这并不是由于 AOX 量对叶片水分状况的影响或由于干旱而发生的扩散限制的发展。相反，AOX 过表达抑制了 WT 中发生的光系统化学计量调整和关键光合成分的损失。结果表明，AOX 量影响 R-L，特别是在严重干旱期间，此时细胞色素途径呼吸可能变得越来越受限。这会影响叶绿体氧化还原状态，影响光合作用装置如何应对日益严重的干旱。特别是，在非能量守恒 R-L 增加的植物中，光合作用生化限制的发展受到抑制。
Chloroplasts have means to manage excess reducing power but these mechanisms may become restricted by rates of ATP turnover. Alternative oxidase (AOX) is a mitochondrial terminal oxidase that uncouples the consumption of reducing power from ATP synthesis.Physiological and biochemical analyses were used to compare respiration and photosynthesis of Nicotiana tabacum wild-type (WT) plants with that of transgenic lines overexpressing AOX, under both well-watered and drought stress conditions.With increasing drought severity, AOX overexpression acted to increase respiration in the light (R-L) relative to WT. CO2 and light response curves indicated that overexpression also improved photosynthetic performance relative to WT, as drought severity increased. This was not due to an effect of AOX amount on leaf water status or the development of the diffusive limitations that occur due to drought. Rather, AOX overexpression dampened photosystem stoichiometry adjustments and losses of key photosynthetic components that occurred in WT.The results indicate that AOX amount influences R-L, particularly during severe drought, when cytochrome pathway respiration may become increasingly restricted. This impacts the chloroplast redox state, influencing how the photosynthetic apparatus responds to increasing drought severity. In particular, the development of biochemical limitations to photosynthesis are dampened in plants with increased nonenergy conserving R-L.