A novel insight into the regulation of light-independent chlorophyll biosynthesis in Larix decidua and Picea abies seedlings
A novel insight into the regulation of light-independent chlorophyll biosynthesis in Larix decidua and Picea abies seedlings
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DOI：
10.1007/s00425-009-0933-3
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发表时间：
2009-06-01
期刊：
影响因子：
4.3
通讯作者：
Hudak, Jan
中科院分区：
文献类型：
--
作者：
Demko, Viktor;Pavlovic, Andrej;Hudak, Jan
非光依赖性叶绿素（Chl）生物合成是在黑暗中组装光合色素蛋白复合物的先决条件。欧洲落叶松幼苗仅在早期发育阶段合成Chl，并且在随后的发育过程中其Chl水平迅速下降。对叶绿素生物合成关键调控步骤的分析表明，最初绿色暗生落叶松子叶的黄化与谷氨酰-tRNA还原酶含量的降低和5-氨基乙酰丙酸合成能力的降低有关。叶绿素前体原叶绿素的水平也下降，在发展落叶松子叶。虽然基因chlL，chlN和chlB编码的光不依赖性原叶绿素氧化还原酶亚基的组成型表达在落叶松幼苗中，ChlB亚基的积累发育调控和ChlB含量在完全发育的子叶下降。在成熟的黑暗生长的落叶松幼苗中，chlB RNA编辑的效率也降低。欧洲云杉（Picea abies（L.）喀斯特在它们的整个发育过程中积累Chl，并显示出对ChlB表达的不同控制。质体超微结构的分析，光合蛋白的Western印迹和光合参数的气体交换和叶绿素荧光测量提供了额外的实验证据之间的差异，黑暗和光明的叶绿素合成云杉和落叶松幼苗。
Light-independent chlorophyll (Chl) biosynthesis is a prerequisite for the assembly of photosynthetic pigment-protein complexes in the dark. Dark-grown Larix decidua Mill. seedlings synthesize Chl only in the early developmental stages and their Chl level rapidly declines during the subsequent development. Our analysis of the key regulatory steps in Chl biosynthesis revealed that etiolation of initially green dark-grown larch cotyledons is connected with decreasing content of glutamyl-tRNA reductase and reduced 5-aminolevulinic acid synthesizing capacity. The level of the Chl precursor protochlorophyllide also declined in the developing larch cotyledons. Although the genes chlL, chlN and chlB encoding subunits of the light-independent protochlorophyllide oxidoreductase were constitutively expressed in the larch seedlings, the accumulation of the ChlB subunit was developmentally regulated and ChlB content decreased in the fully developed cotyledons. The efficiency of chlB RNA-editing was also reduced in the mature dark-grown larch seedlings. In contrast to larch, dark-grown seedlings of Picea abies (L.) Karst. accumulate Chl throughout their whole development and show a different control of ChlB expression. Analysis of the plastid ultrastructure, photosynthetic proteins by Western blotting and photosynthetic parameters by gas exchange and Chl fluorescence measurements provide additional experimental proofs for differences between dark and light Chl biosynthesis in spruce and larch seedlings.