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Overexpression of chlorophyllide a oxygenase (CAO) enlarges the antenna size of photosystem II in Arabidopsis thaliana
Author(s) -
Tanaka Ryouichi,
Koshino Yoshihiro,
Sawa Shinichiro,
Ishiguro Sumie,
Okada Kiyotaka,
Tanaka Ayumi
Publication year - 2001
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2001.2641034.x
Subject(s) - chlorophyll , photosystem ii , chlorophyll b , photosynthesis , arabidopsis thaliana , photosystem , biology , chlorophyll a , cauliflower mosaic virus , botany , antenna (radio) , photosystem i , chemistry , biochemistry , transgene , genetically modified crops , gene , mutant , telecommunications , computer science
Summary The light‐harvesting efficiency of a photosystem is thought to be largely dependent on its photosynthetic antenna size. It has been suggested that antenna size is controlled by the biosynthesis of chlorophyll b . To verify this hypothesis, we overexpressed the enzyme for chlorophyll b biosynthesis, chlorophyllide a oxygenase (CAO), in Arabidopsis thaliana by transforming the plant with cDNA for CAO under the control of the 35S cauliflower mosaic virus promoter. In the early de‐etiolation phase, when the intrinsic CAO expression is very low, the chlorophyll a : b ratio was drastically decreased from 28 to 7.3, indicating that enhancement of chlorophyll b biosynthesis had been successfully achieved. We made the following observations in full‐green rosette leaves of transgenic plants. (1) The chlorophyll a : b ratio was reduced from 2.85 to 2.65. (2) The ratio of the peripheral light‐harvesting complexes (LHCII) to the core antenna complex (CPa) resolved with the green‐gel system increased by 20%. (3) The ratio of the light‐harvesting complex II apoproteins (LHCP) to 47‐kDa chlorophyll a protein (CP47), which was estimated by the results of immunoblotting, increased by 40%. These results indicated that the antenna size increased by at least 10–20% in transgenic plants, suggesting that chlorophyll b biosynthesis controls antenna size. To the best of our knowledge, this is the first report on enlargement of the antenna size by genetic manipulations.