scholarly journals CHLOROPLAST STRUCTURE AND FUNCTION IN ac-20, A MUTANT STRAIN OF CHLAMYDOMONAS REINHARDI

1970 ◽  
Vol 44 (3) ◽  
pp. 540-546 ◽  
Author(s):  
R. P. Levine ◽  
A. Paszewski
Keyword(s):  
Electron Transport ◽  
Mutant Strain ◽  
Electron Transport Chain ◽  
Co2 Fixation ◽  
Photosynthetic Electron Transport ◽  
Structure And Function ◽  
Wild Type ◽  
Carboxylase Activity ◽  
Transport Chain ◽  
And Function

Photosynthetic electron transport is markedly affected in mixotrophic cells of ac-20 because they lack the capacity to form the wild-type level of cytochrome 559, as well as Q, the quencher of fluorescence of photochemical system II. The other components of the electron-transport chain, as well as reactions dependent upon photochemical system I, are unaffected in the mutant strain. These observations are discussed in terms of the previously reported effects of the ac-20 mutation on CO2 fixation and ribulose-1,5-diphosphate carboxylase activity.

scholarly journals CHLOROPLAST STRUCTURE AND FUNCTION IN ac-20, A MUTANT STRAIN OF CHLAMYDOMONAS REINHARDI

1970 ◽  
Vol 44 (3) ◽  
pp. 531-539 ◽  
Author(s):  
R. K. Togasaki ◽  
R. P. Levine
Keyword(s):  
Mutant Strain ◽  
Sodium Acetate ◽  
Co2 Fixation ◽  
Structure And Function ◽  
Pentose Phosphate ◽  
Carboxylase Activity ◽  
Whole Cells ◽  
Photosynthetic Carbon ◽  
Photosynthetic Carbon Metabolism ◽  
And Function

A mutant strain of the green alga Chlamydomonas reinhardi, ac-20, is described in which both the rate of CO2 fixation by whole cells and the rate of carboxylation of ribulose-1,5-diphosphate in cell-free extracts are reduced, particularly when sodium acetate is present in the growth medium. Of the enzymes of the reductive pentose phosphate cycle tested, only ribulose-1,5-diphosphate carboxylase activity is reduced in the mutant strain, and it appears that the low carboxylase activity limits the strain's rate of photosynthetic carbon metabolism. Evidence is presented to show that the fluctuation in the level of the enzyme activity in the presence or absence of acetate results from the fluctuation in the level of some factor(s) limiting the rate of synthesis of the protein.

scholarly journals Effects of Different Planting Densities on Photosynthesis in Maize Determined via Prompt Fluorescence, Delayed Fluorescence and P700 Signals

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 276
Author(s):  
Wanying Chen ◽  
Bo Jia ◽  
Junyu Chen ◽  
Yujiao Feng ◽  
Yue Li ◽  
...  
Keyword(s):  
Electron Transport ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Electron Transport Chain ◽  
Plant Density ◽  
Photosynthetic Electron Transport ◽  
Planting Density ◽  
Strong Impact ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

The mutual shading among individual field-grown maize plants resulting from high planting density inevitably reduces leaf photosynthesis, while regulating the photosynthetic transport chain has a strong impact on photosynthesis. However, the effect of high planting density on the photosynthetic electron transport chain in maize currently remains unclear. In this study, we simultaneously measured prompt chlorophyll a fluorescence (PF), modulated 820 nm reflection (MR) and delayed chlorophyll a fluorescence (DF) in order to investigate the effect of high planting density on the photosynthetic electron transport chain in two maize hybrids widely grown in China. PF transients demonstrated a gradual reduction in their signal amplitude with increasing planting density. In addition, high planting density induced positive J-step and G-bands of the PF transients, reduced the values of PF parameters PIABS, RC/CSO, TRO/ABS, ETO/TRO and REO/ETO, and enhanced ABS/RC and N. MR kinetics showed an increase of their lowest point with increasing high planting density, and thus the values of MR parameters VPSI and VPSII-PSI were reduced. The shapes of DF induction and decay curves were changed by high planting density. In addition, high planting density reduced the values of DF parameters I1, I2, L1 and L2, and enhanced I2/I1. These results suggested that high planting density caused harm on multiple components of maize photosynthetic electron transport chain, including an inactivation of PSII RCs, a blocked electron transfer between QA and QB, a reduction in PSI oxidation and re-reduction activities, and an impaired PSI acceptor side. Moreover, a comparison between PSII and PSI activities demonstrated the greater effect of plant density on the former.

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