Reduction in photosystem II efficiency during a virus-controlled Emiliania huxleyi bloom

2014 ◽  
Vol 495 ◽  
pp. 65-76 ◽  
Author(s):  
SA Kimmance ◽  
MJ Allen ◽  
A Pagarete ◽  
J Martínez Martínez ◽  
WH Wilson
Keyword(s):  
Photosystem Ii ◽  
Emiliania Huxleyi ◽  
Photosystem Ii Efficiency

Light response of D1 turnover and photosystem II efficiency in the seagrassZostera capricorni

Planta ◽  
1996 ◽  
Vol 198 (3) ◽  
pp. 319-323 ◽  
Author(s):  
Yvette S. Flanigan ◽  
Christa Critchley
Keyword(s):  
Photosystem Ii ◽  
Light Response ◽  
Photosystem Ii Efficiency ◽  
D1 Turnover

Photosynthesis, quenching of chlorophyll fluorescence and thermal energy dissipation in iron-deficient sugar beet leaves

1998 ◽  
Vol 25 (4) ◽  
pp. 403 ◽  
Author(s):  
Fermín Morales ◽  
Anunciación Abadía ◽  
Javier Abadía
Keyword(s):  
Energy Dissipation ◽  
Iron Deficiency ◽  
Photosystem Ii ◽  
Sugar Beet ◽  
Electron Flow ◽  
Reaction Centers ◽  
O2 Evolution ◽  
Photosystem Ii Efficiency ◽  
Iron Deficient ◽  
Additional Support

In sugar beet (Beta vulgaris L.) iron deficiency decreased not only the photosynthetic rate but also the actual photosystem II efficiency at steady-state photosynthesis. In moderate iron deficiency, the decrease in actual photosystem II efficiency under illumination was related to closure of photosystem II reaction centers, whereas in severe iron deficiency it was associated to decreases of intrinsic photosystem II efficiency. The O2 evolution, on an absorbed light basis, decreased more than the actual photosystem II efficiency, suggesting the presence of a significant fraction of electron transport to molecular oxygen or the existence of some form of cyclic electron flow. Iron-deficient leaves reduced the excess of light absorbed that cannot be used in photosynthesis not only by decreasing absorptance, but also by dissipating a large part of the light absorbed by the photosystem II antenna. This mechanism, that protects the photosystem II reaction centers through the enhancement of energy dissipation, was related to the de-epoxidation of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) in iron-deficient leaves. These data provide additional support for a role of Z+A in photoprotection under conditions of excess photosynthetic light absorption.

Heat stress and recovery of photosystem II efficiency in wheat (Triticum aestivum L.) cultivars acclimated to different growth temperatures

2014 ◽  
Vol 99 ◽  
pp. 1-8 ◽  
Author(s):  
Mohammad Sabibul Haque ◽  
Katrine Heinsvig Kjaer ◽  
Eva Rosenqvist ◽  
Dew Kumari Sharma ◽  
Carl-Otto Ottosen
Keyword(s):  
Triticum Aestivum ◽  
Heat Stress ◽  
Photosystem Ii ◽  
Triticum Aestivum L ◽  
Photosystem Ii Efficiency

scholarly journals Ionic Homeostasis and Redox Metabolism Upregulated by 24-Epibrassinolide are Crucial for Mitigating Nickel Excess in Soybean Plants, Enhancing Photosystem II Efficiency and Biomass

2021 ◽  
Author(s):  
Marcelo Pires Saraiva ◽  
Camille Ferreira Maia ◽  
Bruno Lemos Batista ◽  
Allan Klynger da Silva Lobato
Keyword(s):  
Photosystem Ii ◽  
Membrane Damage ◽  
Effective Quantum Yield ◽  
Ionic Homeostasis ◽  
Nutrient Contents ◽  
Photosystem Ii Efficiency ◽  
Psii Photochemistry ◽  
Soybean Plants ◽  
Negative Impacts ◽  
Quantum Yield Of Psii

Abstract Nickel (Ni) excess often generates oxidative stress in chloroplasts, causing redox imbalance, membrane damage and negative impacts on biomass. 24-Epibrassinolide (EBR) is a plant growth regulator of great interest in the scientific community because it is a natural molecule extracted from plants that is biodegradable and environmentally friendly. This study aimed to determine whether EBR can induce benefits on ionic homeostasis and antioxidant enzymes and convey possible repercussions on photosystem II efficiency and biomass, more specifically evaluating nutritional, physiological, biochemical and morphological responses in soybean plants subjected to Ni excess. The experiment was randomized with four treatments, including two Ni concentrations (0 and 200 µM Ni, described as – Ni2+ and + Ni2+, respectively) and two concentrations of 24-epibrassinolide (0 and 100 nM EBR, described as – EBR and + EBR, respectively). In general, Ni caused deleterious modulatory effects on chlorophyll fluorescence and gas exchange. In contrast, EBR enhanced the effective quantum yield of PSII photochemistry (15%) and electron transport rate (19%) due to upregulation of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase. Exogenous EBR application promoted significant increases in biomass, and these results were explained by the benefits on nutrient contents and ionic homeostasis, demonstrated by increased Ca2+/Ni2+, Mg2+/Ni+ 2 and Mn2+/Ni2+ ratios.

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