CONICET | Buscador de Institutos y Recursos Humanos

Plants are exposed to a light environment that changes with the time of the day, the time of the year, the degree of cloudiness, the presence of neighbours and the position of plant organs above or below the soil surface. These changes represent both a challenge and an opportunity for plants; a challenge, because the aforementioned variations can generate physiological stress; an opportunity, because the anticipated perception of changes in the light environment provides information that helps plants to adjust to the incoming stressful conditions. Plants bear several photoreceptor types: the red and far-red light receptors phytochromes, the blue-light receptors cryptochromes, phototropins and members of the zeitlupe family, and the UV-B receptor UVR8. Downstream signalling involves a complex network where the photoreceptors repress negative regulators of photomorphogenesis. In darkness, the E3-ligase COP1 labels for destruction several transcription factors required for photomorphogenesis. In the light, the photoreceptors inactivate COP1 by direct interaction. Another mechanism of photoreceptor action involves their direct interaction with transcription factors. For instance, PIF bHLH transcription factors promote skotomorphogenesis in darkness. In the light, phytochromes migrate from the cytoplasm to the nucleus, where they bind PIF proteins and cause their phosphorylation and subsequent destruction. These pathways are connected to the hormone signalling pathways, creating complex networks that link light signals to physiological responses. Our current interest is to understand the mechanisms by which plants can attenuate the impact of non-informative fluctuations of the light environment and integrate different environmental signals controlling the shape and function of its body.