Which of the following pigment is involved in non-photochemical quenching?
Antheraxanthin and zeaxanthin dissipate the energy from the photon as heat preserving the integrity of photosystem II. This dissipation of energy as heat is one form of non-photochemical quenching.
Is PsbS the site of non-photochemical quenching in photosynthesis?
Along with a low thylakoid lumen pH and the presence of de-epoxidized xanthophylls, PsbS is necessary for photoprotective thermal dissipation (qE) of excess absorbed light energy in plants, measured as non-photochemical quenching of chlorophyll fluorescence.
How is Photoinhibition measured?
Photoinhibition can be measured from isolated thylakoid membranes or their subfractions, or from intact cyanobacterial cells by measuring the light-saturated rate of oxygen evolution in the presence of an artificial electron acceptor (quinones and dichlorophenol-indophenol have been used).
How does non photochemical quenching work?
Nonphotochemical chlorophyll fluorescence quenching (NPQ) is a process in which excess absorbed light energy is dissipated into heat. This process takes place in the photosynthetic membranes of plants, algae, and cyanobacteria (Demmig-Adams et al., 2014).
How do you calculate photochemical efficiency?
When all the traps are closed the maximum fluorescence level (Fm) is reached. Variable fluorescence is obtained by subtracting F0 from Fm (Fv = Fm-F0). The potential yield of the photochemical reaction is therefore given by Fv/fm, which is quantitatively related to the photochemical efficiency of PSII.
What is Xanthophyll pigment?
Xanthophylls are yellow pigments that are one of the important divisions of the carotenoid group. The word xanthophylls is made up of the Greek word xanthos, meaning yellow, and phyllon, meaning leaf.
What is PsbS protein?
The PsbS protein controls the macro-organisation of photosystem II complexes in the grana membranes of higher plant chloroplasts.
What is meant by photoinhibition?
Photoinhibition is defined as the decrease in photochemical efficiency experienced in response to intense illumination due to radiation damages.
How do you calculate Npq?
Hence, the level of NPQ can be calculated as (Fm−Fm’)/Fm’. Another parameter, qN, is used to calculate nonphotochemical quenching: qN = (Fm−Fm’)/Fm. This parameter describes the percentage of quenching in a similar manner to ΦPSII.
What is FV FM?
Fv/Fm is a normalized ratio created by dividing variable fluorescence by maximum fluorescence. It is a measurement ratio that represents the maximum potential quantum efficiency of Photosystem II if all capable reaction centers were open.
What is photochemical efficiency?
Photosystem II photochemical efficiency is quantified from chlorophyll fluorescence signals as the ratio of variable to maximal fluorescence (Fv/Fm), with maximal values of 0.85 equaling an 85% efficiency of the conversion of absorbed light into photochemistry.
What is non-photochemical quenching?
Non-photochemical quenching is measured by the quenching of chlorophyll fluorescence and is distinguished from photochemical quenching by applying a bright light pulse to transiently saturate photochemical quenching thus removing its contribution from the observed quenching.
Are quenching coefficients only numbers between 0 and 1?
The calculations showed that the quenching coefficients currently in use are not only numbers between 0 and 1 as one would expect when taking them as a relative measure of the quenching process. Most quenching coefficients must be regarded and interpreted carefully separated from each other.
What are the relative quenching coefficients for de-excitation?
Only the relative quenching coefficients q (P)rel and q (N)rel match together and can be used to demonstrate a shift of the energy de-excitation from the photochemical to the non-photochemical route.
Does antheraxanthin explain non-photochemical fluorescence quenching of xanthophylls?
Gilmore AM, Yamamoto HY(1993) Linear models relating xanthophylls and lumen acidity to non-photochemical fluorescence quenching: evidence that antheraxanthin explains zeaxanthin-independent quenching. Photosynth Res35:67–78