'A blue-light photoreceptor mediates the feedback regulation of photosynthesis' - article in Nature!
ESR Serena Flori and PI Giovanni Finazzi are co-authors on a Nature article 'A blue-light photoreceptor mediates the feedback regulation of photosynthesis'.
Green microalgae, the ancestors of land plants, are microscopic organisms mainly living in the planet waters. Like plants, they are able of performing photosynthesis, a complex metabolic process that converts CO2 into biomass and oxygen using the energy of sunlight. Light is not only the source of energy that fuels photosynthesis but also acts as source of information. Thanks to specific sensors, called photoreceptors, algae respond to the light colour moving towards or against the light (phototaxis), regulating their cell division and other fundamental processes. When light intensity becomes very strong (i.e. under full sunlight) it can become toxic, producing reactive oxygen species and cell damage. To avoid this, photosynthetic organisms can actively decrease their light absorption capacity via photoprotective mechanisms that dissipate the excess light as heat, avoiding cell damage.
In a collaborative work with Japanese and German colleagues the accliphot team light photosynthesis and metabolism has revealed a link between these three functions of the light. We have shown that the green alga Chlamydomonas reinhardti uses a specific blue light photoreceptor (phototropin, PHOT) not only to sense the light colour but also to integrate information about the light intensity, ultimately activating the photoprotective mechanism that dissipates the excess light for photosynthesis in the form of heat (Fig. 1).
We propose that the mechanism that brings together light sensing, utilisation and dissipation evolved in the ocean, the ancestral environment where photosynthetic organisms evolved, there where blue light dominates the available spectrum. It then contributed to the capacity of photosynthetic organism to colonise the land, and eventually disappeared in plants, which are exposed to the full visible spectrum (1)
1. Petroutsos D, Tokutsu R, Maruyama S, Flori S, Greiner A, Magneschi L, Cusant L, Kottke T, Mittag M, Hegemann P, Finazzi G, Minagawa J. (2016) A blue-light photoreceptor mediates the feedback regulation of photosynthesis. Nature. 537:563-566