The regulation of photosynthetic electron transport during nutrient deprivation in Chlamydomonas reinhardtii

• Published in: Plant physiology (Bethesda) 1998-05, Vol.117 (1), p.129-139
• Main Authors: Wykoff, D.D. (The Carnegie Institution of Washington, Stanford, CA.), Davies, J.P, Melis, A, Grossman, A.R
• Format: Article
• Language: English
• Subjects: ACCLIMATIZATION; ADAPTACION; ADAPTATION; Animals; AZUFRE; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Biological and medical sciences; CARENCE EN SUBSTANCE NUTRITIVE; CHLAMYDOMONAS REINHARDTII; Chlamydomonas reinhardtii - metabolism; Chlamydomonas reinhardtii - physiology; Chlorophylls; CHOIX DE LA DATE; Culture Media - metabolism; DEFICIENCIAS NUTRITIVAS; ELECCION DE LA EPOCA; ELECTRON TRANSFER; Electron Transport; EXPRESION GENICA; EXPRESSION DES GENES; Fluorescence; FOSFORO; FOTOSISTEMAS; Fundamental and applied biological sciences. Psychology; GENE; GENE EXPRESSION; GENES; Light; MEASUREMENT; MEDICION; Membrane Proteins; Membrane Transport Proteins; MESURE; Metabolism; NET ASSIMILATION RATE; NUTRIENT DEFICIENCIES; OXIDOREDUCTIONS; OXIRREDUCION; OXYDOREDUCTION; PHOSPHORE; PHOSPHORUS; Phosphorus - deficiency; Phosphorus - metabolism; Photons; Photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; Photosynthetic Reaction Center Complex Proteins - metabolism; PHOTOSYSTEM I; PHOTOSYSTEM II; PHOTOSYSTEME; PHOTOSYSTEMS; Plant cells; Plant physiology and development; Plants; Plastoquinone - metabolism; QUINONAS; QUINONE; QUINONES; SOUFRE; Starvation; STRESS RESPONSE; Sulfur; Sulfur - deficiency; Sulfur - metabolism; SULPHUR; Thylakoids; TIMING; Whole Plant, Environmental, and Stress Physiology; Xanthophylls
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.117.1.129

The light-saturated rate of photosynthetic O2 evolution in Chlamydomonas reinhardtii declined by approximately 75% on a per-cell basis after 4 d of P starvation or 1 d of S starvation. Quantitation of the partial reactions of photosynthetic electron transport demonstrated that the light-saturated rate of photosystem (PS) I activity was unaffected by P or S limitation, whereas light-saturated PSII activity was reduced by more than 50%. This decline in PSII activity correlated with a decline in both the maximal quantum efficiency of PSII and the accumulation of the secondary quinone electron acceptor of PSII nonreducing centers (PSII centers capable of performing a charge separation but unable to reduce the plastoquinone pool). In addition to a decline in the light-saturated rate of O2 evolution, there was reduced efficiency of excitation energy transfer to the reaction centers of PSII (because of dissipation of absorbed light energy as heat and because of a transition to state 2). These findings establish a common suite of alterations in photosynthetic electron transport that results in decreased linear electron flow when C. reinhardtii is limited for either P or S. It was interesting that the decline in the maximum quantum efficiency of PSII and the accumulation of the secondary quinone electron acceptor of PSII nonreducing centers were regulated specifically during S-limited growth by the SacI gene product, which was previously shown to be critical for the acclimation of C. reinhardtii to S limitation (J.P. Davies, F.H. Yildiz, and A.R. Grossman [1996] EMBO J 15: 2150-2159)