Chlorophyll synthesis in a deetiolated-(det340) mutant of Arabidopsis without NADPH-protochlorophyllide (PChlide) oxidoreductase (POR) A and photoactive PChlide-F655
Chlorophyll synthesis in a deetiolated-(det340) mutant of Arabidopsis without NADPH-protochlorophyllide (PChlide) oxidoreductase (POR) A and photoactive PChlide-F655
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DOI：
10.1105/tpc.7.12.2081
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发表时间：
1995-12-01
期刊：
影响因子：
11.6
通讯作者：
Apel, K
中科院分区：
文献类型：
--
作者：
Lebedev, N;vanCleve, B;Apel, K
拟南芥中的叶绿素 (Chl) 合成由两种光依赖性 NADPH-原叶绿素内酯 (PChlide) 氧化还原酶 (POR) 控制，一种 (FOR A) 在光照开始时在黄化幼苗中短暂活跃，另一种 (FOR B) 也在绿色植物中发挥作用。这两种酶在光诱导深色生长幼苗绿化过程中的功能已在野生型和拟南芥的去黄化（det340）突变体。 def突变的后果之一是FOR A组成性下调，因此FOR A酶的合成被关闭。当在黑暗中生长时，det340突变体缺乏FOR A和光活性PChlide-F655物种，但保留第二种PChlide还原酶FOR B。以前，光活性PChlide-F655通常被认为是导致Chi形成的唯一PChlide形式。尽管 det340 突变体缺乏 FOR A 和光活性 PChlide-F655，但在光照下仍能呈现绿色。然而，Chi积累异常进行，在光照开始时，det340突变体的幼苗极易受到光氧化损伤，并且仅在极低的光强度下积累Chi，它们形成光系统I和II的核心复合体，但几乎完全缺乏光捕获结构。这项研究的结果表明，除了在光照黑暗生长的野生型植物中广泛研究的 Chi 合成途径之外，还存在由 POR B 驱动且不需要 POR A 的 Chi 合成的第二个分支。
Chlorophyll (Chl) synthesis in Arabidopsis is controlled by two light-dependent NADPH-protochlorophyllide (PChlide) oxidoreductases (PORs), one (FOR A) that is active transiently in etiolated seedlings at the beginning of illumination and another (FOR B) that also operates in green plants, The function of these two enzymes during the light-induced greening of dark-grown seedlings has been studied in the wild type and a deetiolated (det340) mutant of Arabidopsis. One of the consequences of the def mutation is that FOR A is constitutively down-regulated, and therefore, synthesis of the FOR A enzyme is shut off. When grown in the dark, the det340 mutant lacks FOR A and the photoactive PChlide-F655 species but maintains the second PChlide reductase, FOR B, Previously, photoactive PChlide-F655 has often been considered to be the only PChlide form that leads to Chi formation. Despite its deficiency in FOR A and photoactive PChlide-F655, the det340 mutant is able to green when placed in the light. Chi accumulation, however, proceeds abnormally, At the beginning of illumination, seedlings of det340 mutants are extremely susceptible to photooxidative damage and accumulate Chi only at extremely low light intensities, They form core complexes of photosystems I and II but are almost completely devoid of light-harvesting structures. The results of this study demonstrate that in addition to the route of Chi synthesis that has been studied extensively in illuminated dark-grown wild-type plants, a second branch of Chi synthesis exists that is driven by POR B and does not require POR A.