Effects of frost hardening on photosynthetic quantum yield, chlorophyll organization, and energy distribution between the two photosystems in Scots pine

1986 ◽  
Vol 64 (4) ◽  
pp. 748-753 ◽  
Author(s):  
Gunnar Öquist ◽  
Martin Strand
Keyword(s):  
Quantum Yield ◽  
Energy Distribution ◽  
Scots Pine ◽  
Photosynthetic Efficiency ◽  
Protein Complexes ◽  
Protein A ◽  
Photosynthetic Apparatus ◽  
Frost Hardening ◽  
Photosynthetic Quantum Yield ◽  
Chlorophyll Protein

Seedlings of Scots pine (Pinus sylvestris L.), with only primary needles, were frost hardened under a photoperiod of 8 h and a temperature of 4 °C for 6–9 weeks. The effects of frost hardening were studied on (i) the photosynthetic efficiency as defined by the quantum yield of CO2 uptake under light-limiting conditions, (ii) the energy partitioning between the two photosystems as analyzed by 77 K fluorescence spectroscopy, and (iii) the distribution of solubilized chlorophyll–protein complexes after electrophoretic separation. It was found that frost hardening had no significant effects either on the photosynthetic quantum yield measured at 23–25 °C or on the energy distribution between the two photosystems. Despite these findings, frost hardening affected the chlorophyll organization so that the proportion of aggregated complexes such as chlorophyll–protein 1a and the dimeric form of light-harvesting chlorophyll–protein decreased. Frost hardening also decreased the amount of chlorophyll–protein a and increased the amount of free, solubilized chlorophyll in the gel scan profile. From these results it is concluded that frost hardening affects the chemical interactions within the antennae organization of the photosynthetic apparatus but that these changes have no significant effects on the energy distribution between the two photosystems or on the photosynthetic efficiency as defined by the quantum yield for CO2 uptake.

scholarly journals Role of the HSP70 Homologue from Chloroplasts in the Assembly of the Photosynthetic Apparatus

1993 ◽  
Author(s):  
Rachel Nechushtai ◽  
Parag Chitnis
Keyword(s):  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Crop Productivity ◽  
Cdna Clones ◽  
Light Harvesting Complex ◽  
Complex Protein ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

The major goal of the proposed research was to study the role of a 70-kDa heat shock cognate protein from chloroplasts (ct-HSP70) in the assembly of chlorophyll-protein complexes. The latters are mostly important in allowing photosynthesis to occur. Photosynthesis is at the heart of crop productivity and the knowledge of the biogenesis of the photosynthetic apparatus is essential to manipulate the efficiency of photosynthesis. The characterization of the function of the ct-HSP70 was planned to be studied in vitro by assaying its capability to physically interact with the thylakoid proteins and to assist their assembly into thylakoid membranes. We planned to identify regions in the light-harvesting complex protein (LHCP) that interact with the ct-HSP70 and characterize the interaction between them. We also intended to isolate cDNA clones encoding ct-HSP70, sequence them, express one of them in E. coli and use the purified protein for functional assays. The research in this BARD proposal aimed at providing insights and aid in understanding the mechanism by which plants may respond to the heat stress. Since plants often experience increased temperatures.

scholarly journals Structural changes and lateral redistribution of photosystem II during donor side photoinhibition of thylakoids.

1992 ◽  
Vol 119 (2) ◽  
pp. 325-335 ◽  
Author(s):  
R Barbato ◽  
G Friso ◽  
F Rigoni ◽  
F Dalla Vecchia ◽  
G M Giacometti
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Structural Changes ◽  
Protein Complexes ◽  
Gradient Centrifugation ◽  
Photosynthetic Apparatus ◽  
Topological Stability ◽  
Donor Side ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

The structural and topological stability of thylakoid components under photoinhibitory conditions (4,500 microE.m-2.s-1 white light) was studied on Mn depleted thylakoids isolated from spinach leaves. After various exposures to photoinhibitory light, the chlorophyll-protein complexes of both photosystems I and II were separated by sucrose gradient centrifugation and analysed by Western blotting, using a set of polyclonals raised against various apoproteins of the photosynthetic apparatus. A series of events occurring during donor side photoinhibition are described for photosystem II, including: (a) lowering of the oligomerization state of the photosystem II core; (b) cleavage of 32-kD protein D1 at specific sites; (c) dissociation of chlorophyll-protein CP43 from the photosystem II core; and (d) migration of damaged photosystem II components from the grana to the stroma lamellae. A tentative scheme for the succession of these events is illustrated. Some effects of photoinhibition on photosystem I are also reported involving dissociation of antenna chlorophyll-proteins LHCI from the photosystem I reaction center.

scholarly journals The Arabidopsis Accessions Selection Is Crucial: Insight from Photosynthetic Studies

2021 ◽  
Vol 22 (18) ◽  
pp. 9866
Author(s):  
Joanna Wójtowicz ◽  
Katarzyna B. Gieczewska
Keyword(s):  
Arabidopsis Thaliana ◽  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Adaptive Plasticity ◽  
Natural Genetic Variation ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein ◽  
Pigment Distribution ◽  
Photosynthetic Machinery ◽  
Characteristic Features

Natural genetic variation in photosynthesis is strictly associated with the remarkable adaptive plasticity observed amongst Arabidopsis thaliana accessions derived from environmentally distinct regions. Exploration of the characteristic features of the photosynthetic machinery could reveal the regulatory mechanisms underlying those traits. In this study, we performed a detailed characterisation and comparison of photosynthesis performance and spectral properties of the photosynthetic apparatus in the following selected Arabidopsis thaliana accessions commonly used in laboratories as background lines: Col-0, Col-1, Col-2, Col-8, Ler-0, and Ws-2. The main focus was to distinguish the characteristic disparities for every accession in photosynthetic efficiency that could be accountable for their remarkable plasticity to adapt. The biophysical and biochemical analysis of the thylakoid membranes in control conditions revealed differences in lipid-to-protein contribution, Chlorophyll-to-Carotenoid ratio (Chl/Car), and xanthophyll cycle pigment distribution among accessions. We presented that such changes led to disparities in the arrangement of the Chlorophyll-Protein complexes, the PSI/PSII ratio, and the lateral mobility of the thylakoid membrane, with the most significant aberrations detected in the Ler-0 and Ws-2 accessions. We concluded that selecting an accession suitable for specific research on the photosynthetic process is essential for optimising the experiment.

Photoinhibition in vivo and in vitro Involves Weakly Coupled Chlorophyll–Protein Complexes‡¶

2002 ◽  
Vol 75 (6) ◽  
pp. 613 ◽  
Author(s):  
Stefano Santabarbara ◽  
Ilaria Cazzalini ◽  
Andrea Rivadossi ◽  
Flavio M. Garlaschi ◽  
Giuseppe Zucchelli ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Weakly Coupled ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

scholarly journals Transcriptome and proteome analysis suggest enhanced photosynthesis in tetraploid Liriodendron sino-americanum

2021 ◽  
Author(s):  
Tingting Chen ◽  
Yu Sheng ◽  
Zhaodong Hao ◽  
Xiaofei Long ◽  
Fangfang Fu ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Protein Complexes ◽  
Proteome Analysis ◽  
Tree Height ◽  
Photosynthetic Electron Transport ◽  
Industrial Applications ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein ◽  
Photosynthesis Genes ◽  
Underlying Mechanisms

Abstract Polyploidy generally provides an advantage in phenotypic variation and growth vigor. However, the underlying mechanisms remain poorly understood. The tetraploid L. sino-americanum exhibits altered morphology compared to its diploid counterpart, including larger, thicker and deeper green leaves, bigger stomata, thicker stems and increased tree height. Such characteristics can be useful in ornamental and industrial applications. To elucidate the molecular mechanisms behind this variation, we performed a comparative transcriptome and proteome analysis. Our transcriptome data indicated that some photosynthesis genes and pathways were differentially altered and enriched in tetraploid L. sino-americanum, mainly related to F-type ATPase, the cytochrome b6/f complex, photosynthetic electron transport, the light harvesting chlorophyll protein complexes, photosystem I and II. Most of the differentially expressed proteins we could identify are also involved in photosynthesis. Our physiological results showed that tetraploids have an enhanced photosynthetic capacity, concomitant with great levels of sugar and starch in leaves. This suggests that tetraploid L. sino-americanum might experience comprehensive transcriptome reprogramming of genes related to photosynthesis. This study has especially emphasized molecular changes involved in photosynthesis that accompany polyploidy, and provides a possible explanation for the altered phenotype of polyploidy plants in comparison to their diploid form.

Fluorescence as a tool in photosynthesis research: application in studies of photoinhibition, cold acclimation and freezing stress

1989 ◽  
Vol 323 (1216) ◽  
pp. 281-293 ◽  
Keyword(s):  
Quantum Yield ◽  
Cold Acclimation ◽  
Spinacia Oleracea ◽  
Photosynthetic Apparatus ◽  
Fluorescence Induction ◽  
High Light ◽  
Thermal Dissipation ◽  
Freezing Stress ◽  
Chlorophyll Fluorescence Induction ◽  
Freezing And Thawing

Chlorophyll fluorescence induction (at 20 °C and 77 K) and quenching were analysed in relation to effects of environmental stresses imposed by chilling in high light and by freezing and thawing of spinach ( Spinacia oleracea L.) leaves. The data indicate that cold acclimation of spinach plants, which leads to increased frost tolerance of the leaves, results in decreased susceptibility to photoinhibition of photosynthesis at chilling temperatures. When plants acclimated to 18 °C and 260-300 µmol quanta m -2 s -1 were exposed to higher light (550 µmol quanta m -2 s -1 ) at 4 °C, they developed strong photoinhibition, as characterized by decreased quantum yield of O 2 evolution and decreased ratio of variable: maximum fluorescence (F V /F M ) of photosystem II. The decrease in F V /F M resulted from a decline in F V and an increase in F 0 . The F V /F M ratio was lowered to a significantly greater extent when induction was recorded at 20 °C, as compared with 77 K. The effects related to photoinhibition were fully reversible at 18 °C in dim light. Plants that had been cold-acclimated for 10 days exhibited slightly decreased quantum yield and lowered F V /F M ratio. However, they did not show further photoinhibition on exposure to 550 µmol quanta m -2 s -1 at 4 °C. The reversible photoinhibition is discussed as a protective pathway serving for thermal dissipation of excessive light energy. It is hypothesized that such a mechanism prevents destruction of the photosynthetic apparatus, until other means of protection become effective during long-term acclimation to high light. Inhibition of photosynthetic carbon assimilation caused by freezing and thawing of leaves in the dark was closely correlated with inhibition of photochemical fluorescence quenching (q Q ). As a sensitive response of the thylakoid membranes to freezing stress, the energy-dependent quenching, q E , was inhibited. Only more severe impact of freezing caused a significant decline in the F V /F M ratio. It is concluded that measurements of fluorescence induction signals ( F V /F M ratios) provide a sensitive tool with which to investigate photoinhibition, whereas freezing damage to the photosynthetic system can be detected more readily by the quenching coefficients q Q and q E than by F V /F M ratios.

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