Thylakoids reorganization enables driving photosynthesis under far‐red light in the microalga Nannochloropsis gaditana

Summary Oxygenic photosynthesis is driven by visible light in most photosynthetic organisms, with exceptions in a few cyanobacteria and microalgae species, which can extend the light absorption to far‐red (FR) wavelengths, by synthesizing new pigments or shifting the antennae absorption range beyond 700 nm. In this work, we describe a novel mechanism of acclimation in the marine microalga Nannochloropsis gaditana , which resulted capable of growth relying solely on FR light. Unexpectedly, the response did not involve the synthesis of red‐shifted absorption forms but a peculiar reorganization of chloroplasts. The abundance of photosynthetic complexes changed, with an increased accumulation of all pigment‐binding proteins and photosystem II. Chloroplasts became bigger and thylakoid membranes increased in number, occupying almost all the organelle volume, showing also newly observed structures, composed of a central superstack with perpendicular electron‐dense interconnections, that we propose to name thylakoidal bodies . To the best of our knowledge, these results describe a novel acclimation strategy to FR light, overall highlighting that the biodiversity of responses to FR light is currently underestimated.