scholarly journals Resolution of the Photosystem I and Photosystem II contributions to chlorophyll fluorescence of intact leaves at room temperature

2002 ◽  
Vol 1556 (2-3) ◽  
pp. 239-246 ◽  
Author(s):  
Fabrice Franck ◽  
Philippe Juneau ◽  
Radovan Popovic
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Room Temperature ◽  
Intact Leaves

Humidity-sensitive Degreening and Regreening of Leaves of Borya nitida Labill. As Followed by Changes in Chlorophyll Fluorescence

1982 ◽  
Vol 9 (5) ◽  
pp. 587 ◽  
Author(s):  
SE Hethzerington ◽  
RM Smillie
Keyword(s):  
Chlorophyll Fluorescence ◽  
Relative Humidity ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Fluorescence Induction ◽  
Physiological Age ◽  
Chlorophyll Fluorescence Induction ◽  
Induction Kinetics ◽  
Mediated Electron Transfer

Fast and slow chlorophyll fluorescence induction kinetics were used to follow changes in photosynthetic activity during humidity-sensitive degreening and regreening of leaves of Borya nidita Labill. During dry periods the leaves of this desiccation-tolerant plant lose chlorophyll, becoming yellow-brown and upon rehydration turn green again. This degreening process can be simulated in detached leaves by slow dehydration at 96% relative humidity. Under these conditions changes in chlorophyll fluorescence in vivo and the activities of photosystems I and II in chloroplasts isolated from dehydrated leaves indicated that degreening was accompanied initially by a stimulation of photosystem II activity and a gradual decrease in photosystem I-mediated electron transfer, while at advanced stages of degreening both photosystems were lost. Control leaves detached and kept at 100% relative humidity remained green and showed little change in chlorophyll fluorescence kinetics. During the rehydration and subsequent regreening of dry yellow leaves, photosystem I activity appeared to recover faster than photosystem II. The ability of the leaves to recover and regreen from the dried state, either on the plant or after detachment, depended upon the physiological age of the leaves at the time of dehydration.

The Role of D 1* in Light-Induced D 1 Protein Turnover in Leaves

1993 ◽  
Vol 48 (3-4) ◽  
pp. 246-250
Author(s):  
Anna J. Syme ◽  
Harald R . Bolhàr-N ordenkampf ◽  
Christa Critchley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Light Intensity ◽  
Protein Turnover ◽  
Photochemical Efficiency ◽  
Light Conditions ◽  
Ps Ii ◽  
Light Intensities ◽  
Intact Leaves

Abstract Light-induced degradation of the D 1 protein of photosystem II (PS II) was determined by radioactive pulse-chase labelling experiments in intact leaves of Schefflera polybotrya. PS II photochemical efficiency was monitored by measuring chlorophyll fluorescence. A significant and consistent decline in the Fv/ Fm ratio was taken to indicate photoinhibition. The formation and degradation of a modified form of the D 1 protein, D 1*, was different under photoinhibi-tory or non-photoinhibitory light conditions. At photoinhibitory irradiance greater amounts of D 1 * were formed relative to D 1, and the degradation of D 1* was slower when compared with non-photoinhibitory irradiance. The formation and degradation of D 1* were therefore shown to be at least partly light intensity dependent. Higher light intensities appeared to slow D 1* degradation, which suggests a modification in PS II turnover properties.

Fluorescence and Photochemical Properties of Plants with Defective Photosystem II

1980 ◽  
Vol 35 (5-6) ◽  
pp. 461-466 ◽  
Author(s):  
Wilhelm Menke ◽  
Georg H. Schmid
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
Emission Spectrum ◽  
Photosystem I ◽  
Room Temperature ◽  
Fluorescence Emission ◽  
Fluorescence Emission Spectrum ◽  
Wild Type ◽  
Fully Functioning ◽  
Fluorescence Energy

Abstract The mykotrophic orchid Neottia nidus-avis does not evolve oxygen in the light but is able to perform photophosphorylation. The low temperature fluorescence emission spectrum lacks the 680 and 690 nm bands. Hence, the spectroscopic chlorophyll a forms which are attributed to photosystem II do not occur in plastids of this orchid. The low temperature excitation spectrum of photosystem I fluorescence exhibits a maximum at 666 nm. The position of this maximum appears not to be influenced by energy transfer and corresponds to the absorption maximum of the chlorophyll form which emits the photosystem I fluorescence. Energy migration, however, occurs from carotenoids whose absorption spectrum is shifted to longer wavelengths and which cause the yellow-brown color of the Neottia plastids. Room temperature fluorescence emission shows after the onset of light no variable part. Despite the fact that plastids of the tobacco mutant NC 95 at most evolve only traces of oxygen the low temperature emission spectrum shows the three bands which are usually observed with fully functioning chloroplasts. However, the two bands at 680 and 690 nm are distinctly lower than with the wild type. The variable portion of room temperature fluorescence is barely detectable. In line with the very low capacity for oxygen evolution, rates of electron transport partial reactions in the region of photosystem II are extremely low. In agreement with this observation no 690 nm absorption change signal is detected. However, a normal P+700 signal is seen. In the presence of electron donors like reduced phenazine methosulfate the decay time of the P+700 signal is faster than with the wild type. The yellow tobacco mutant Su/su var. aurea which exhibits at high light intensities higher rates of photosynthesis than the wild type shows at low temperature an emission spectrum with stronger photosystem II bands than the wild type.

scholarly journals Physiological and Transcriptomic Analysis Reveals the Responses and Difference to High Temperature and Humidity Stress in Two Melon Genotypes

2022 ◽  
Vol 23 (2) ◽  
pp. 734
Author(s):  
Jinyang Weng ◽  
Asad Rehman ◽  
Pengli Li ◽  
Liying Chang ◽  
Yidong Zhang ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
High Temperature ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Chloroplast Ultrastructure ◽  
Future Research ◽  
Leaf Water Content ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Temperature And Humidity

Due to the frequent occurrence of continuous high temperatures and heavy rain in summer, extremely high-temperature and high-humidity environments occur, which seriously harms crop growth. High temperature and humidity (HTH) stress have become the main environmental factors of combined stress in summer. The responses of morphological indexes, physiological and biochemical indexes, gas exchange parameters, and chlorophyll fluorescence parameters were measured and combined with chloroplast ultrastructure and transcriptome sequencing to analyze the reasons for the difference in tolerance to HTH stress in HTH-sensitive ‘JIN TAI LANG’ and HTH-tolerant ‘JIN DI’ varieties. The results showed that with the extension of stress time, the superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) activities of the two melon varieties increased rapidly, the leaf water content increased, and the tolerant varieties showed stronger antioxidant capacity. Among the sensitive cultivars, Pn, Fv/Fm, photosystem II, and photosystem I chlorophyll fluorescence parameters were severely inhibited and decreased rapidly with the extension of stress time, while the HTH-tolerant cultivars slightly decreased. The cell membrane and chloroplast damage in sensitive cultivars were more severe, and Lhca1, Lhca3, and Lhca4 proteins in photosystem II and Lhcb1-Lhcb6 proteins in photosystem I were inhibited compared with those in the tolerant cultivar. These conclusions may be the main reason for the different tolerances of the two cultivars. These findings will provide new insights into the response of other crops to HTH stress and also provide a basis for future research on the mechanism of HTH resistance in melon.

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