scholarly journals High temperature effects on the response of photosynthesis to light in sweet orange plants infected with Xylella fastidiosa

2003 ◽  
Vol 15 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Rafael Vasconcelos Ribeiro ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira ◽  
Carlos Pimentel
Keyword(s):  
High Temperature ◽  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Quantum Efficiency ◽  
Temperature Effects ◽  
Sweet Orange ◽  
Xylella Fastidiosa ◽  
Fluorescence Yield ◽  
Photosynthetic Oxygen Evolution ◽  
Photosynthetic Oxygen

The objective of this study was to evaluate the high temperature effects on the response of photosynthesis to light in sweet orange plants infected with Xylella fastidiosa. This vascular bacterium is the causal agent of the citrus variegated chlorosis that causes severe economical losses to the Brazilian citrus industry. The responses of the photosynthetic oxygen evolution and the parameters related to chlorophyll a fluorescence to the increase in light intensity were evaluated at 35ºC and 45ºC in both healthy and infected leaf discs. The increase in temperature affected the photosynthetic apparatus of both healthy and infected plants, although infected plants showed higher photochemical sensitivity at the higher temperature (e.g. in the potential quantum efficiency of photosystem II, maximum and basal fluorescence yield, and in the relation between variable and basal fluorescence yield). This higher sensitivity of infected plants was not reflected in the overall photosynthetic reaction, since photosynthetic oxygen evolution values did not vary at 45ºC. Healthy and infected plants showed differences in photosynthetic oxygen evolution but displayed similar effective quantum efficiency of photosystem II as well as apparent electron transport rates at 35ºC. These results suggest that the limitations in photosynthesis observed on the infected plants might arise through impaired biochemical reactions.

Interaction of polyamines with proteins of photosystem II: Cation binding and photosynthetic oxygen evolution

2007 ◽  
Vol 833 (1-3) ◽  
pp. 169-174 ◽  
Author(s):  
R. Beauchemin ◽  
J. Harnois ◽  
R. Rouillon ◽  
H.A. Tajmir-Riahi ◽  
R. Carpentier
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Cation Binding ◽  
Photosynthetic Oxygen Evolution ◽  
Photosynthetic Oxygen

Cyclic Electron Flow Around Photosystem II as Examined by Photosynthetic Oxygen Evolution Induced by Short Light Flashes

1997 ◽  
Vol 52 (3-4) ◽  
pp. 175-179 ◽  
Author(s):  
W. I. Gruszecki ◽  
K. Strzałka ◽  
A. Radunz ◽  
G. H. Schmid
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Molecular Mechanisms ◽  
Electron Flow ◽  
Red Light ◽  
Cyclic Electron Flow ◽  
Photosynthetic Oxygen Evolution ◽  
Absorption Region ◽  
Photosynthetic Oxygen ◽  
Light Flashes

Abstract Photosynthetic oxygen evolution from photosystem II particles was analyzed as consequence of a train of short (5 μs) flashes of different light quality and different intensities to study cyclic electron flow around photosystem II. Damped oscillations of the amplitudes of O2-evolution corresponding to a flash sequence were fitted numerically and analyzed in terms of a nonhomogeneous distribution of misses, represented by the probability parameter αi. Application of red light, known to promote cyclic electron flow around photosystem II (Gruszecki et al., 1995) results in a considerable increase of all αi, indicating that at the molecular level the misses may be interpreted as resulting from a competition for the reduction of oxidized P680 between cyclic electron flow and the electron flow coming from the water splitting enzyme. In accordance with previous findings, application of light flashes of the spectrum covering the absorption region of carotenoids resulted in an inhibition of cyclic electron flow and a pronounced decrease of the level of the miss parameter. Possible molecular mechanisms for the activity control of this cyclic electron transport around photosystem II by carotenoids are discussed.

Different sensitivities of photosystem II in green algae and cyanobacteria to phenylurea and phenol-type herbicides: effect on electron donor side

2017 ◽  
Vol 72 (7-8) ◽  
pp. 315-324 ◽  
Author(s):  
Ekaterina K. Yotsova ◽  
Martin A. Stefanov ◽  
Anelia G. Dobrikova ◽  
Emilia L. Apostolova
Keyword(s):  
Photosystem Ii ◽  
Kinetic Parameters ◽  
Oxygen Evolution ◽  
Oxygen Evolving Complex ◽  
Photosynthetic Oxygen Evolution ◽  
Donor Side ◽  
Short Term Treatment ◽  
Psii Photochemistry ◽  
Photosynthetic Oxygen ◽  
Oxygen Evolving

AbstractThe effects of short-term treatment with phenylurea (DCMU, isoproturon) and phenol-type (ioxynil) herbicides on the green algaChlorella kessleriand the cyanobacteriumSynechocystis salinawith different organizations of photosystem II (PSII) were investigated using pulse amplitude modulated (PAM) chlorophyll fluorescence and photosynthetic oxygen evolution measured by polarographic oxygen electrodes (Clark-type and Joliot-type). The photosynthetic oxygen evolution showed stronger inhibition than the PSII photochemistry. The effects of the studied herbicides on both algal and cyanobacterial cells decreased in the following order: DCMU>isoproturon>ioxynil. Furthermore, we observed that the number of blocked PSII centers increased significantly after DCMU treatment (204–250 times) and slightly after ioxynil treatment (19–35 times) in comparison with the control cells. This study suggests that the herbicides affect not only the acceptor side but also the donor side of PSII by modifications of the Mn cluster of the oxygen-evolving complex. We propose that one of the reasons for the different PSII inhibitions caused by herbicides is their influence, in different extents, on the kinetic parameters of the oxygen-evolving reactions (the initial S0−S1state distribution, the number of blocked centers SB, the turnover time of Sistates, misses and double hits). The relationship between the herbicide-induced inhibition and the changes in the kinetic parameters is discussed.

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