Chlororespiration and Grana Hyperstacking: How an Arabidopsis Double Mutant Can Survive Despite Defects in Starch Biosynthesis and Daily Carbon Export from Chloroplasts
Chlororespiration and Grana Hyperstacking: How an Arabidopsis Double Mutant Can Survive Despite Defects in Starch Biosynthesis and Daily Carbon Export from Chloroplasts
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DOI：
10.1104/pp.108.128124
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发表时间：
2009-01-01
期刊：
影响因子：
7.4
通讯作者：
Fluegge, Ulf-Ingo
中科院分区：
文献类型：
--
作者：
Haeusler, Rainer E.;Geimer, Stefan;Fluegge, Ulf-Ingo
淀粉生物合成和磷酸丙糖/磷酸转位子（adg1-1/tpt-1）受损的拟南芥（Arabidopsis thaliana）双突变体的特征是光同化物的利用减少，并伴随着光合作用光反应中产生的能量和能量的消耗。为了保证生存，双突变体以生长迟缓、光合电子传递下降80%、叶绿素含量减少、黑暗中质体醌的还原状态增强（高达50%）、叶子氧化还原平衡的扰动（NADPH/NADP比率增加和抗坏血酸/脱氢抗坏血酸比率降低）来应对这种代谢挑战， 基粒类囊体的过度堆积，以及质体球数量的增加。耗氧量的增加以及替代线粒体和叶绿体氧化酶（AOX 和 PTOX）抑制剂的应用表明，氯呼吸以及线粒体呼吸参与了黑暗中增强的质体醌还原状态。与野生型相比，adg1-1/tpt-1 中 PTOX 和 AOX 的转录量减少，与质体 NADH 还原酶 (NDH1) 相关的核编码成分增加。细胞色素 b(559) 被认为参与光系统 II 的再氧化，但在转录水平上不受调节。基粒类囊体的超堆积模拟了对弱光的适应，质体球数量的增加表明对氧化应激增强的反应。叶绿体组织的改变与氧化还原平衡的扰动相结合表明，adg1-1/tpt-1可以成为体内研究控制核和质体编码光合基因协调表达的逆行信号机制的工具。
An Arabidopsis (Arabidopsis thaliana) double mutant impaired in starch biosynthesis and the triose phosphate/phosphate translocator (adg1-1/tpt-1) is characterized by a diminished utilization of photoassimilates and the concomitant consumption of reducing power and energy produced in the photosynthetic light reaction. In order to guarantee survival, the double mutant responds to this metabolic challenge with growth retardation, an 80% decline in photosynthetic electron transport, diminished chlorophyll contents, an enhanced reduction state of plastoquinone in the dark (up to 50%), a perturbation of the redox poise in leaves (increased NADPH/NADP ratios and decreased ascorbate/dehydroascorbate ratios), hyperstacking of grana thylakoids, and an increased number of plastoglobules. Enhanced oxygen consumption and applications of inhibitors of alternative mitochondrial and chloroplast oxidases (AOX and PTOX) suggest that chlororespiration as well as mitochondrial respiration are involved in the enhanced plastoquinone reduction state in the dark. Transcript amounts of PTOX and AOX were diminished and nucleus-encoded components related to plastidic NADH reductase (NDH1) were increased in adg1-1/tpt-1 compared with the wild type. Cytochrome b(559), proposed to be involved in the reoxidation of photosystem II, was not regulated at the transcriptional level. The hyperstacking of grana thylakoids mimics adaptation to low light, and increased plastoglobule numbers suggest a response to enhanced oxidative stress. Altered chloroplast organization combined with perturbations in the redox poise suggests that adg1-1/tpt-1 could be a tool for the in vivo study of retrograde signaling mechanisms controlling the coordinated expression of nucleus- and plastome-encoded photosynthetic genes.