Photoprotection and growth under different lights of Arabidopsis single and double mutants for energy dissipation (npq4) and state transitions (pph1)

International audienceNon Photochemical Quenching (NPQ) is a short-term regulation important to maintain efficient photosynthesis and to avoid photooxydative damages by dissipation of excess energy. Full activation of NPQ in plants requires the protonation of the PsbS protein, which is the sensor of the low lumenal pH triggering the thermal dissipation. State transitions are a second important photosynthetic regulation to respond to changes in light quality and unbalanced excitation of photosystems. State transitions allow energy redistribution between PSI and PSII through the reversible exchange of LHCII antenna complexes between photosystems thank to the opposite action of the STN7 kinase and PPH1 phosphatase: phosphorylation of LHCII promotes its mobilization from PSII to PSI, while dephosphorylation has the opposite effect. In this work, we produced the pph1/npq4 double mutant and characterized some photosynthetic, growth and reproduction properties in comparison with wild type and single mutant plants in high and low light conditions. Results indicate that in high light, the pph1 mutant maintains good photoprotection ability, while npq4 plants show more susceptibility to photodamages. The pph1/npq4 double mutant showed a resistance to high light stress similar to that of the single npq4 mutant. In low light condition, the single mutants showed a significant increase of growth and flowering as compared to wild type plants and this effect was further enhanced in the pph1/npq4 double mutant. Results suggest that photosynthetic optimisation to improve crop growth and productivity might be possible, at least under controlled low light conditions, by modifying NPQ and state transitions regulations. Key word: Non-photochemical quenching, PsbS protein, PPH1/TAP38 protein, plant growth, state transitions. Key Message: Arabidopsis single and double mutants for energy dissipation (npq4) and state transition (pph1, blocked in state II) show enhanced growth and flowers+siliques production under controlled low light conditions