Overexpression of chlorophyllide a oxygenase (CAO) enlarges the antenna size of photosystem II in Arabidopsis thaliana

Citation
R. Tanaka et al., Overexpression of chlorophyllide a oxygenase (CAO) enlarges the antenna size of photosystem II in Arabidopsis thaliana, PLANT J, 26(4), 2001, pp. 365-373
Citations number
58
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences","Animal & Plant Sciences
Journal title
PLANT JOURNAL
ISSN journal
0960-7412 → ACNP
Volume
26
Issue
4
Year of publication
2001
Pages
365 - 373
Database
ISI
SICI code
0960-7412(200105)26:4<365:OOCAO(>2.0.ZU;2-3
Abstract
The light-harvesting efficiency of a photosystem is thought to be largely d ependent on its photosynthetic antenna size. It has been suggested that ant enna size is controlled by the biosynthesis of chlorophyll b. To verify thi s hypothesis, we overexpressed the enzyme for chlorophyll b biosynthesis, c hlorophyllide a oxygenase (CAO), in Arabidopsis thaliana by transforming th e plant with cDNA for CAO under the control of the 35S cauliflower mosaic v irus promoter. In the early de-etiolation phase, when the intrinsic CAO exp ression is very low, the chlorophyll a: b ratio was drastically decreased f rom 28 to 7.3, indicating that enhancement of chlorophyll b biosynthesis ha d been successfully achieved. We made the following observations in full-gr een 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-harvestin g complexes (LHCII) to the core antenna complex (CPa) resolved with the gre en-gel system increased by 20%. (3) The ratio of the light-harvesting compl ex 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 th e antenna size by genetic manipulations.