Signalling mechanism of phototropin-mediated chloroplast movement in Arabidopsis

To efficiently use light for photosynthesis, chloroplasts move to the appropriate location according to ambient light conditions. Chloroplasts relocate towards dimly lit cell parts to maximise light capture (the accumulation response), whereas they escape from the strong light to minimise photodamage (the avoidance response). In most plant species, blue light is the most effective to induce chloroplast movements. Since the first report of light-induced chloroplast movement in 1856, many researchers have tried to elucidate the molecular mechanism underlying chloroplast movement including the photoreceptor system, the signal transduction and the motility system. However, the molecular mechanism remained unknown until a molecular genetic analysis usingArabidopsis thalianaas a model plant has been applied in the analysis of chloroplast movement. In this article, we review physiological and molecular analyses that have studied signal transduction of light-induced chloroplast movement.