Inducible Repression of Nuclear-Encoded Subunits of the Cytochrome b6f Complex in Tobacco Reveals an Extraordinarily Long Lifetime of the Complex
Inducible Repression of Nuclear-Encoded Subunits of the Cytochrome b6f Complex in Tobacco Reveals an Extraordinarily Long Lifetime of the Complex
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DOI：
10.1104/pp.114.243741
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发表时间：
2014-08-01
期刊：
影响因子：
7.4
通讯作者：
Schoettler, Mark Aurel
中科院分区：
文献类型：
--
作者：
Hojka, Marta;Thiele, Wolfram;Schoettler, Mark Aurel
烟草细胞色素B（6）f复合物的生物发生似乎仅限于幼叶，这表明该复合物的寿命很长。为了直接确定其寿命，我们采用了乙醇诱导的RNA干扰（RNAi）方法，针对必需的核编码的Rieske蛋白（PetC）和小M亚基（PetM），其在高等植物中的功能是未知的。PetM和PetC RNAi转化体的幼展开叶迅速漂白并发生坏死，而成熟叶保持绿色，所述成熟叶的光合机构在RNAi诱导前完全组装。与这些表型一致，细胞色素B（6）f复合物积累和线性电子传递能力在两个RNAi转化体的幼叶中被强烈抑制，表明M亚基与Rieske蛋白一样对于细胞色素B（6）f复合物积累是必需的。在成熟叶片中，所有的光合参数是无法区分的野生型，即使在14天的诱导。由于PetM和PetC的RNAi阻遏在幼叶和成熟叶中都是高效的，这些数据表明细胞色素B（6）f复合物的寿命至少为1周。成熟叶片中细胞色素B（6）f复合物生物合成的关闭可能代表叶片衰老程序的第一个专门步骤的一部分。
The biogenesis of the cytochrome b(6)f complex in tobacco (Nicotiana tabacum) seems to be restricted to young leaves, suggesting a high lifetime of the complex. To directly determine its lifetime, we employed an ethanol-inducible RNA interference (RNAi) approach targeted against the essential nuclear-encoded Rieske protein (PetC) and the small M subunit (PetM), whose function in higher plants is unknown. Young expanding leaves of both PetM and PetC RNAi transformants bleached rapidly and developed necroses, while mature leaves, whose photosynthetic apparatus was fully assembled before RNAi induction, stayed green. In line with these phenotypes, cytochrome b(6)f complex accumulation and linear electron transport capacity were strongly repressed in young leaves of both RNAi transformants, showing that the M subunit is as essential for cytochrome b(6)f complex accumulation as the Rieske protein. In mature leaves, all photosynthetic parameters were indistinguishable from the wild type even after 14 d of induction. As RNAi repression of PetM and PetC was highly efficient in both young and mature leaves, these data indicate a lifetime of the cytochrome b(6)f complex of at least 1 week. The switch-off of cytochrome b(6)f complex biogenesis in mature leaves may represent part of the first dedicated step of the leaf senescence program.