Abstract
Glutathione is a ubiquitous tripeptide that is synthesized via two reactions dependent on photosynthetic ATP production. To study whether glutathione is associated with photosynthesis regulation, we investigated effects of decreased glutathione levels on photosynthesis using an Arabidopsis mutant, cad2-1, which has 15-30% of wild-type levels of glutathione. The cad2-1 mutant showed low photosynthetic electron transports and high non-photochemical quenching (NPQ). These results are considered to suggest that low levels of glutathione suppress photosynthesis. The mutant had 75% Rubisco content of the wild-type. It has been found that the another Calvin cycle enzyme, aldorase, is regulated by glutathione. Taking these into account, it is considered that low levels of glutathione suppress the Calvin cycle. We will discuss relationship between glutathione levels and the Calvin cycle based on aldorase activity and CO2 assimilation in cad2-1 under various CO2 concentrations.
