The role of <i>Arabidopsis thaliana</i> photoreceptors in regulating the process of state transitions

Abstract

The initial formation of the photosynthetic apparatus in plants occurs during photomorphogenesis. The red/far-red (phytochromes) and blue (cryptochrome) light protein-photoreceptors play the most important role in photomorphogenesis initiation and regulation. The exited phytochrome and cryptochrome molecules can interact with transcription factors, changing the expression of nuclear genes, which encode the proteins of the plant photosynthetic apparatus. Since light is a variable factor, plants have developed appropriate adaptation mechanisms, including their photosynthetic apparatus protection. The mechanism of state transitions ensures a rapid adaptation of the photosynthetic apparatus. This adaptation mechanism increases the adsorption efficiency under current light conditions and prevents intensive generation of active forms of oxygen in chloroplasts, which leads to photo-oxidation and even cell death. This work aims to determine the role of photoreceptors - phytochromes A and B, as well as cryptochrome 1 and 2 - in regulating the process of state transitions in the Arabidopsis thaliana model plant. Arabidopsis mutants with the defects on A and B phytochromes and cryptochrome 1 and 2 genes were used as the research objects. The blue native electrophoresis in polyacrylamide gel was used to visualise state transitions. It was found that these photoreceptors had no direct effect on the redox-regulation of the state transitions mechanism in Arabidopsis. Presumably, these photoreceptors protect the photosynthetic apparatus from excessive light not by regulating the state transitions but indirectly, through regulating the chlorophyll, carotenoid and antioxidant components content.