Regulation of photosynthetic light harvesting by nitrogen assimilation in the green alga Selenastrum minutum

FEBS Letters

Bruce, Doug¹  Turpin, David H.² 

[1]Department of Biological Sciences, Brock University, St. St.Catharines, Ont. L2S 3A1, Canada

[2]Department of Biology, Queen 's University, Kingston, Ont. K7L 3N6, Canada

关键词: Photosynthesis;    State transition;    Chlorophyll fluorescence;    Nitrogen assimilation;    Selenastrum minutum;   

DOI  :  10.1016/0014-5793(90)80714-T

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The interaction of whole cell metabolism with the distribution of excitation energy between photosystem 2 (PS2) and photosystem 1 (PS1), the light state transition, was investigated in vivo in the green alga Selenastrum minutum. Nitrogen limited cells of S. minutum were presented with a pulse of either NH₄ ⁺ or NO₃ ⁻ in the light. As shown previously, CO₂ fixation is inhibited and high rates of N assimilation ensue [(1986) Plant Physiol. 81, 273–279]. NH₄ ⁺ assimilation has a much higher requirement ratio for ATP/NADPH than either CO₂ or NO₃ ⁻ assimilation and thus drastically increases the demand for ATP relative to reducing power. Room temperature chlorophyll a fluorescence kinetic measurements showed that a reversible non-photochemical quenching of PS2 fluorescence accompanied the assimilation of NH₄ ⁺ but not the assimilation of NO₃ ⁻ or CO₂. 77K fluorescence emission spectra taken from samples removed at regular intervals during NH⁺ ₄assimilation showed that the non-photochemical quenching of PS2 was accompanied by a complementary increase in the fluorescence yield of PS1, characteristic of a transition to state 2. Our data suggests that S. minutum responds to the increased demand for ATP/NADPH during NH₄ assimilation by inducing the light state transition to direct more excitation energy to PS1 at the expense of PS2 to increase the production of ATP by cyclic electron transport.

【 授权许可】

Unknown