Photosynthesis Research

, Volume 85, Issue 3, pp 327–340

Effects of Chlorophyllide a Oxygenase Overexpression on Light Acclimation inArabidopsis thaliana

Regular paper

DOI: 10.1007/s11120-005-6807-z

Cite this article as:
Tanaka, R. & Tanaka, A. Photosynth Res (2005) 85: 327. doi:10.1007/s11120-005-6807-z


Land plants change the compositions of light-harvesting complexes (LHC) and chlorophyll (Chl) a/b ratios in response to the variable light environments which they encounter. In this study, we attempted to determine the mechanism which regulates Chl a/b ratios and whether the changes in Chl a/b ratios are essential in regulation of LHC accumulation during light acclimation. We hypothesized that changes in the mRNA levels for chlorophyll a oxygenase (CAO) involved in Chl b biosynthesis are an essential part of light response of Chl a/b ratios and LHC accumulation. We also examined the light-intensity dependent response of CAO-overexpression and wild-type Arabidopsis thaliana plants. When wild-type plants were acclimated from low-light (LL) to high-light (HL) conditions, CAO mRNA levels decreased and the Chl a/b ratio increased. In transgenic plants overexpressing CAO, the Chl a/b ratio remained low under HL conditions; thereby suggesting that changes in the CAO mRNA levels are necessary for those in Chl a/b ratios upon light acclimation. Under HL conditions, the accumulation of Lhcb1, Lhcb3 and Lhcb6 was enhanced in plants overexpressing CAO. On the contrary, in a CAO-deficient mutant, chlorina 1-1, theaccumulation of Lhcb1, Lhcb2, Lhcb3, Lhcb6 and Lhca4 was reduced. In comparison to wild-type, β-carotene levels were reduced in CAO-overexpressing plants, while they were elevated in chlorina 1-1 mutants. These results imply that the transcriptional control of CAO is a part of the regulatory mechanism for the accumulation of a distinct set of LHC proteins upon light acclimation.


Arabidopsis thaliana, chlorina-1chlorophyll bchlorophyllide a oxygenaseLHCII



chlorophyllide a oxygenase






chlorophyll pro- tein


light-harvesting protein complex


light-harvesting chlorophyll a/b-protein of PSI


light-harvesting chlorophyll a/b-protein of PSII

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Institute of Low Temperature Science, CRESTHokkaido University,Japan Science and Technology CorporationSapporoJapan