Expression Analysis of Genes Associated with the Induction of the Carbon-Concentrating Mechanism in Chlamydomonas reinhardtii.

摘要

Acclimation to varying CO(2) concentrations and light intensities is associated with the monitoring of environmental changes by controlling genetic and physiological responses through CO(2) and light signal transduction. While CO(2) and light signals are indispensable for photosynthesis, and these environmental factors have been proposed as strongly associated with each other, studies linking these components are largely limited to work on higher plants. In this study, we examined the physiological characteristics of a green alga, Chlamydomonas reinhardtii, exposed to various light intensities or CO(2) concentrations. Acclimation to CO(2)-limiting conditions by Chlamydomonas requires the induction of a carbon-concentrating mechanism (CCM) to allow the uptake of inorganic carbon (Ci) and increase the affinity for Ci. We revealed that the induction of the CCM is not solely dependent on absolute environmental Ci concentrations but is also affected by light intensity. Using a cDNA array containing 10,368 expressed sequence tags, we also obtained global expression profiles related to the physiological responses. The induction of several CCM-associated genes was strongly affected by high light as well as CO(2) concentrations. We identified novel candidates for Ci transporters and CO(2)-responsive regulatory factors whose expression levels were significantly increased during the induction of the CCM.