Effects of Chlorophyllide a Oxygenase Overexpression on Light Acclimation inArabidopsis thaliana
Effects of Chlorophyllide a Oxygenase Overexpression on Light Acclimation inArabidopsis thaliana
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DOI：
10.1007/s11120-005-6807-z
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发表时间：
2005-09
影响因子：
3.7
通讯作者：
R. Tanaka;A. Tanaka
中科院分区：
文献类型：
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作者：
R. Tanaka;A. Tanaka
陆地植物在不同的光环境下，会改变其捕光复合物（LHC）和叶绿素（Chl）a/bratios的组成。在本研究中，我们试图确定Chla/bratios的调节机制，以及Chla/bratios的变化是否对光驯化过程中LHC积累的调节至关重要。我们推测参与叶绿素合成的叶绿素加氧酶（CAO） mRNA水平的变化是Chla/bratios光响应和LHC积累的重要组成部分。我们还研究了cao -过表达和野生型拟南芥的光强依赖性反应。当野生型植物从弱光（LL）环境适应到强光（HL）环境时，CAOmRNA水平降低，Chla/bratio升高。在过表达cao的转基因植株中，HL条件下的Chla/bratio仍然很低；因此，这表明caomrna水平的变化对于Chla/bratios的光驯化是必要的。在HL条件下，过表达cao的植株中Lhcb1、Lhcb3和Lhcb6的积累增强。相反，在缺乏acao的突变体chlorina 1-1中，Lhcb1、Lhcb2、Lhcb3、Lhcb6和Lhca4的积累量减少。与野生型相比，β-胡萝卜素水平在过表达cao的植株中降低，而在氯化1-1突变体中升高。这些结果表明，cais的转录控制是光驯化过程中LHC蛋白积累的调控机制的一部分。
Land plants change the compositions of light-harvesting complexes (LHC) and chlorophyll (Chl)a/bratios in response to the variable light environments which they encounter. In this study, we attempted to determine the mechanism which regulates Chla/bratios and whether the changes in Chla/bratios are essential in regulation of LHC accumulation during light acclimation. We hypothesized that changes in the mRNA levels for chlorophyllaoxygenase (CAO) involved in Chlbbiosynthesis are an essential part of light response of Chla/bratios and LHC accumulation. We also examined the light-intensity dependent response ofCAO-overexpression and wild-typeArabidopsis thalianaplants. When wild-type plants were acclimated from low-light (LL) to high-light (HL) conditions,CAOmRNA levels decreased and the Chla/bratio increased. In transgenic plants overexpressingCAO, the Chla/bratio remained low under HL conditions; thereby suggesting that changes in theCAOmRNA levels are necessary for those in Chla/bratios upon light acclimation. Under HL conditions, the accumulation of Lhcb1, Lhcb3 and Lhcb6 was enhanced in plants overexpressingCAO. On the contrary, in aCAO-deficient mutant,chlorina 1-1, theaccumulation of Lhcb1, Lhcb2, Lhcb3, Lhcb6 and Lhca4 was reduced. In comparison to wild-type, β-carotene levels were reduced inCAO-overexpressing plants, while they were elevated inchlorina 1-1mutants.These results imply that the transcriptional control ofCAOis a part of the regulatory mechanism for the accumulation of a distinct set of LHC proteins upon light acclimation.