Arabidopsis PsbP-Like Protein 1 Facilitates the Assembly of the Photosystem II Supercomplexes and Optimizes Plant Fitness under Fluctuating Light

2020 ◽  
Vol 61 (6) ◽  
pp. 1168-1180
Author(s):  
Yufen Che ◽  
Shoko Kusama ◽  
Shintaro Matsui ◽  
Marjaana Suorsa ◽  
Takeshi Nakano ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Intensity ◽  
Early Stage ◽  
Light Harvesting Complexes ◽  
Green Plants ◽  
Fluctuating Light ◽  
Exact Function ◽  
Stroma Lamellae ◽  
Assembly Factor ◽  
Changing Light

Abstract In green plants, photosystem II (PSII) forms multisubunit supercomplexes (SCs) containing a dimeric core and light-harvesting complexes (LHCs). In this study, we show that Arabidopsis thaliana PsbP-like protein 1 (PPL1) is involved in the assembly of the PSII SCs and is required for adaptation to changing light intensity. PPL1 is a homolog of PsbP protein that optimizes the water-oxidizing reaction of PSII in green plants and is required for the efficient repair of photodamaged PSII; however, its exact function has been unknown. PPL1 was enriched in stroma lamellae and grana margins and associated with PSII subcomplexes including PSII monomers and PSII dimers, and several LHCII assemblies, while PPL1 was not detected in PSII–LHCII SCs. In a PPL1 null mutant (ppl1-2), assembly of CP43, PsbR and PsbW was affected, resulting in a reduced accumulation of PSII SCs even under moderate light intensity. This caused the abnormal association of LHCII in ppl1-2, as indicated by lower maximal quantum efficiency of PSII (Fv/Fm) and accelerated State 1 to State 2 transitions. These differences would lower the capability of plants to adapt to changing light environments, thereby leading to reduced growth under natural fluctuating light environments. Phylogenetic and structural analyses suggest that PPL1 is closely related to its cyanobacterial homolog CyanoP, which functions as an assembly factor in the early stage of PSII biogenesis. Our results suggest that PPL1 has a similar function, but the data also indicate that it could aid the association of LHCII with PSII.

scholarly journals PSB27: A thylakoid protein enabling Arabidopsis to adapt to changing light intensity

2015 ◽  
Vol 112 (5) ◽  
pp. 1613-1618 ◽  
Author(s):  
Xin Hou ◽  
Aigen Fu ◽  
Veder J. Garcia ◽  
Bob B. Buchanan ◽  
Sheng Luan
Keyword(s):  
Photosystem Ii ◽  
Light Intensity ◽  
Light Adaptation ◽  
Light Exposure ◽  
Starch Accumulation ◽  
State Transitions ◽  
Potential Candidate ◽  
Subsequent Work ◽  
Variable Intensity ◽  
Changing Light

In earlier studies we have identified FKBP20-2 and CYP38 as soluble proteins of the chloroplast thylakoid lumen that are required for the formation of photosystem II supercomplexes (PSII SCs). Subsequent work has identified another potential candidate functional in SC formation (PSB27). We have followed up on this possibility and isolated mutants defective in the PSB27 gene. In addition to lack of PSII SCs, mutant plants were severely stunted when cultivated with light of variable intensity. The stunted growth was associated with lower PSII efficiency and defective starch accumulation. In response to high light exposure, the mutant plants also displayed enhanced ROS production, leading to decreased biosynthesis of anthocyanin. Unexpectedly, we detected a second defect in the mutant, namely in CP26, an antenna protein known to be required for the formation of PSII SCs that has been linked to state transitions. Lack of PSII SCs was found to be independent of PSB27, but was due to a mutation in the previously described cp26 gene that we found had no effect on light adaptation. The present results suggest that PSII SCs, despite being required for state transitions, are not associated with acclimation to changing light intensity. Our results are consistent with the conclusion that PSB27 plays an essential role in enabling plants to adapt to fluctuating light intensity through a mechanism distinct from photosystem II supercomplexes and state transitions.

scholarly journals PHOTOKINESIS AND TONIC EFFECT OF LIGHT IN UNIONICOLA

1932 ◽  
Vol 16 (2) ◽  
pp. 349-355 ◽  
Author(s):  
John H. Welsh
Keyword(s):  
Light Intensity ◽  
Simple Relation ◽  
Combined Effect ◽  
Direct Proportion ◽  
Water Mite ◽  
Locomotor Muscles ◽  
Leg Movement ◽  
Changing Light ◽  
Effect Of Light

1. The speed of progression of Unionicola, a water mite, is influenced by light; and over a certain range increases as a function of the light intensity. 2. The relation between speed and light intensity is not a simple one, as the speed of progression is due to the combined effect of amplitude of steps and frequency of leg movement. 3. The amplitude of stride increases in direct proportion to the logarithm of the light intensity, while the frequency of stepping has no such simple relation to intensity. 4. The change in length of stride with changing light intensity indicates a tonic effect of light on the locomotor muscles. Such an effect has been observed previously in studies of orientation, due to unequal illumination, which produces changes in posture.

Factors affecting the hydrogen cyanide potential of forage sorghum.

1990 ◽  
Vol 41 (6) ◽  
pp. 1093 ◽  
Author(s):  
JL Wheeler ◽  
C Mulcahy ◽  
JJ Walcott ◽  
GG Rapp
Keyword(s):  
Water Stress ◽  
Light Intensity ◽  
Hydrogen Cyanide ◽  
Dry Matter ◽  
Early Stage ◽  
Phosphorus Fertilizer ◽  
Factors Affecting ◽  
Forage Sorghum ◽  
Plant Maturity ◽  
Selection For

The effect of seven factors, namely genotype, plant maturity, nitrogen fertilizer, phosphorus fertilizer, water stress, light intensity and temperature, on the hydrogen cyanide potential (HCNp) of forage sorghum was studied in three pot experiments. Fivefold differences occurred between genotypes in HCNp, with a breeder's line, X45106, selected for low HCNp having a maximum of 520 mg HCN kg-1 DM (dry matter) compared with 2300 and 2450 mg kg-1 DM for cvs Zulu and Silk respectively. In X45 106, HCNp (mg HCN kg-1 DM) declined curvilinearly with age d (days from sowing) (HCNp=8460- 320d+ 3.1d2) and linearly in Silk (HCNp = 9020 - 110d), but the decline in Zulu was not statistically significant. Nitrogen (equivalent to 200 kg ha-1 of N) increased HCN, (P< 0.001), but more so in full light (100 mg kg-1 compared with 1430 mg kg-1) than in 50% shade (190 mg kg-1 compared with 690 mg kg-1). In one experiment, acute water stress appeared to reduce HCNp, but this was confounded with the strong decline due to aging. In another study, acute water stress had no effect on HCNp. Neither the application of superphosphate nor change in light intensity, nor change in temperature had a direct significant effect on HCNp in these studies. Breeding and selection for low HCNp appears a promising approach to ensuring that sorghum plants will provide non-toxic forage from an early stage of growth.

scholarly journals A chloroplast thylakoid lumen protein is required for proper photosynthetic acclimation of plants under fluctuating light environments

2017 ◽  
Vol 114 (38) ◽  
pp. E8110-E8117 ◽  
Author(s):  
Jun Liu ◽  
Robert L. Last
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
High Irradiance ◽  
Light Conditions ◽  
Agricultural Plant ◽  
Photosynthetic Organisms ◽  
Fluctuating Light ◽  
Stress Susceptibility ◽  
Efficiency And Productivity ◽  
Photosynthetic Adaptation

Despite our increasingly sophisticated understanding of mechanisms ensuring efficient photosynthesis under laboratory-controlled light conditions, less is known about the regulation of photosynthesis under fluctuating light. This is important because—in nature—photosynthetic organisms experience rapid and extreme changes in sunlight, potentially causing deleterious effects on photosynthetic efficiency and productivity. Here we report that the chloroplast thylakoid lumenal protein MAINTENANCE OF PHOTOSYSTEM II UNDER HIGH LIGHT 2 (MPH2; encoded byAt4g02530) is required for growth acclimation ofArabidopsis thalianaplants under controlled photoinhibitory light and fluctuating light environments. Evidence is presented thatmph2mutant light stress susceptibility results from a defect in photosystem II (PSII) repair, and our results are consistent with the hypothesis that MPH2 is involved in disassembling monomeric complexes during regeneration of dimeric functional PSII supercomplexes. Moreover,mph2—and previously characterized PSII repair-defective mutants—exhibited reduced growth under fluctuating light conditions, while PSII photoprotection-impaired mutants did not. These findings suggest that repair is not only required for PSII maintenance under static high-irradiance light conditions but is also a regulatory mechanism facilitating photosynthetic adaptation under fluctuating light environments. This work has implications for improvement of agricultural plant productivity through engineering PSII repair.

scholarly journals Elaborate pupils in skates may help camouflage the eye

2018 ◽  
Author(s):  
Sean Youn ◽  
Corey Okinaka ◽  
Lydia M Mäthger
Keyword(s):  
Light Intensity ◽  
Spatial Frequency ◽  
Experimental Evidence ◽  
Pupillary Response ◽  
Pupil Dilation ◽  
Primary Factor ◽  
Natural Substrate ◽  
Spatial Frequencies ◽  
Pupillary Responses ◽  
Changing Light

AbstractThe little skate Leucoraja erinacea has elaborately shaped pupils, whose characteristics and functions have not been studied extensively. It has been suggested that such pupil shapes may camouflage the eye; yet, no experimental evidence has been presented to support this claim. Skates are bottom-dwellers that often bury into the substrate with their eyes protruding. If these pupils serve any camouflage function, we expect there to be a pupillary response related to the spatial frequency (“graininess”) of the background against which the eye is viewed. Here, we tested whether skate pupils dilate or constrict in response to background spatial frequency. We placed skates on background substrates with different spatial frequencies and recorded pupillary responses at three light intensities. In experiment 1, the skates’ pupillary response to three artificial checkerboards of different spatial frequencies was recorded. Skates responded to changing light intensity with pupil dilation/constriction; yet, their pupils did not change in response to spatial frequency. In experiment 2, in which skates could bury into three natural substrates with different spatial frequencies, such that their eyes protruded above the substrate, the pupils showed a subtle but statistically significant response to changes in substrate spatial frequency. Given the same light intensity, the smaller the spatial frequency of the natural substrate, the more constricted the pupil. While light intensity is the primary factor determining pupil dilation, these experiments are the first to show that pupils also change in response to background spatial frequency, which suggests that the pupil may aid in camouflaging the eye.

scholarly journals Determination of the Stoichiometry and Strength of Binding of Xanthophylls to the Photosystem II Light Harvesting Complexes

1999 ◽  
Vol 274 (15) ◽  
pp. 10458-10465 ◽  
Author(s):  
Alexander V. Ruban ◽  
Pamela J. Lee ◽  
Mark Wentworth ◽  
Andrew J. Young ◽  
Peter Horton
Keyword(s):  
Photosystem Ii ◽  
Light Harvesting ◽  
Light Harvesting Complexes
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