Diurnal dynamics of nonphotochemical quenching in Arabidopsis npq mutants assessed by solar‐induced fluorescence and reflectance measurements in the field

Abstract

This article is protected by copyright. All rights reserved • Solar-induced fluorescence (SIF) is highly relevant in mapping photosynthesis from remotesensing platforms. This requires linking SIF to photosynthesis and understanding the role of non-photochemical quenching (NPQ) mechanisms under field conditions. Hence, active and passive fluorescence were measured in Arabidopsis thaliana with altered NPQ in outdoor conditions. • Plants had mutations in either violaxanthin de-epoxidase (npq1) or PsbS protein (npq4), resulting in reduced NPQ capacity. Parallel measurements of NPQ, photosystem II efficiency, SIF and spectral reflectance (ρ) were conducted diurnally on one sunny summer day and two consecutive days during a simulated cold spell. • Results showed that both npq mutants had higher levels of SIF compared to wild type. Changes in reflectance were related to changes in the violaxanthin-antheraxanthin-zeaxanthin cycle and not to PsbS-mediated conformational changes. When plants were exposed to cold temperatures, rapid onset of photoinhibition strongly quenched SIF in all lines. • Using well-characterized npq mutants of Arabidopsis, we could show for the first time the quantitative link between SIF, photosynthetic efficiency, NPQ components and leaf reflectance. We discuss the functional potential and limitations of SIF and reflectance measurements for estimating photosynthetic efficiency and NPQ in the field.

NAC Transcription Factor PwNAC11 Activates ERD1 by Interaction with ABF3 and DREB2A to Enhance Drought Tolerance in Transgenic Arabidopsis

“…Meanwhile, the NPQ, an indicator of plant to disperse excess light energy in the form of heat to protect itself under adverse conditions, showed no significant differences under normal and dehydration conditions in control groups, while PwNAC11 OE lines showed increased NPQ values after drought treatment. These results verified the complete network of photoprotective mechanism in OE lines [38]. Recent studies revealed that the inhibition of light energy conversion could produce more excess excitation energy and promote the accumulation of ROS in plant [39].…”

Light Quality-Dependent Regulation of Non-Photochemical Quenching in Tomato Plants

“…Third, the photoinhibitory component of NPQ, qI, is slowly reversible (within hours) and comprises processes related to either PSII core inactivation characterized by reduced maximal photochemical efficiency (Fv/Fm) [ 14 ] or slowly relaxing quenching, recently termed qH [ 3 ]. The qT component, which indicates state transitions, is triggered by low light conditions to balance the energy distribution of light energy between PSII and photosystem I (PSI) [ 15 ].…”

A System Dynamics Approach to Model Photosynthesis at Leaf Level Under Fluctuating Light

“…In fact, external conditions are rarely stable in natural environments, so plants need to continuously adjust to optimize the carbon uptake in these dynamic conditions (Kaiser et al, 2018). Different adjustments can be operated by plants depending on the time scale considered (Kono and Terashima, 2014): in the fast temporal scale, plants respond by regulating the mechanisms involved in photochemical (Kono and Terashima, 2014;Kaiser et al, 2018) and nonphotochemical processes (Acebron et al, 2021), activating the Calvin Cycle enzymes (Porcar-Castell et al, 2006) and moving their chloroplasts within the leaves (Kaiser et al, 2015); slower adjustments can then be due to the regulation of the stomata (Buckley, 2017;Vialet-Chabrand et al, 2017b;Matthews et al, 2018), the movements of the leaves within the canopy (as photonastic movements or due to the wind), and the adaptative adjustments in nitrogen and chlorophyll content (Posada et al, 2009;Zhang et al, 2016).…”