Faculty Opinions recommendation of Roles of CmpR, a LysR family transcriptional regulator, in acclimation of the cyanobacterium Synechococcus sp. strain PCC 7942 to low-CO(2) and high-light conditions.

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

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Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

Zeitschrift für Naturforschung C ◽

10.1515/znc-1986-5-618 ◽

1986 ◽

Vol 41 (5-6) ◽

pp. 597-603 ◽

Cited By ~ 33

Author(s):

Aloysius Wild ◽

Matthias Höpfner ◽

Wolfgang Rühle ◽

Michael Richter

Keyword(s):

Photosystem Ii ◽

Functional Organization ◽

Photosynthetic Apparatus ◽

High Light ◽

Molar Ratio ◽

Light Conditions ◽

Low Light ◽

Pigment System ◽

Transport Chain ◽

The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

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