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标题：Differential use of two cyclic electron flows around photosystem I for driving CO2-concentration mechanism in C4 photosynthesis
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作者：Atsushi Takabayashi ; Masahiro Kishine ; Kozi Asada 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：46
页码：16898-16903
DOI：10.1073/pnas.0507095102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Whereas linear electron flow (LEF) in photosynthesis produces both ATP and NADPH, the cyclic electron flow (CEF) around photosystem I has been shown to produce only ATP. Two alternative routes have been shown for CEF; NAD(P)H dehydrogenase (NDH)- and ferredoxin:plastoquinone oxidoreductase (FQR)-dependent flows, but their physiological relevance has not been elucidated in detail. Meanwhile, because C4 photosynthesis requires more ATP than does C3 photosynthesis to concentrate CO2, it has not been clear how the extra ATP is produced. In this study, to elucidate whether CEF contributes to the additional ATP needed in C4 photosynthesis, we estimated the amounts of PGR5, which participates in FQR-dependent flow, and NDH-H, a subunit of NDH, in four C4 species. Although the expression profiles of PGR5 did not correlate well with the additional ATP requirement, NDH was greatly expressed in mesophyll cells in the NAD-malic enzyme (ME) species, and in bundle-sheath cells in NADP-ME species, where there is a strong need for ATP in the respective cells. Our results indicate that CEF via NDH plays a central role in driving the CO2-concentrating mechanism in C4 photosynthesis.
关键词：ATP synthesis ; ferredoxin:plastoquinone oxidoreductase ; NAD(P)H dehydrogenase ; PGR5 ; plant