A light-induced decrease in the photochemical reflectance index (PRI) can be used to estimate the energy-dependent component of non-photochemical quenching under heat stress and soil drought in pea, wheat, and pumpkin

2020 ◽  
Vol 146 (1-3) ◽  
pp. 175-187 ◽  
Author(s):  
Lyubov Yudina ◽  
Ekaterina Sukhova ◽  
Ekaterina Gromova ◽  
Vladimir Nerush ◽  
Vladimir Vodeneev ◽  
...  
Keyword(s):  
Heat Stress ◽  
Photochemical Quenching ◽  
Soil Drought ◽  
Photochemical Reflectance Index ◽  
Dependent Component ◽  
Non Photochemical Quenching ◽  
Energy Dependent

scholarly journals Ascorbate deficiency does not limit non-photochemical quenching in Chlamydomonas reinhardtii

2019 ◽  
Author(s):  
André Vidal-Meireles ◽  
Dávid Tóth ◽  
László Kovács ◽  
Juliane Neupert ◽  
Szilvia Z. Tóth
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Vascular Plants ◽  
Regulation Of Gene Expression ◽  
Growth Conditions ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Knockout Mutant ◽  
Dependent Component ◽  
Non Photochemical Quenching ◽  
Energy Dependent

SummaryAscorbate (vitamin C) plays essential roles in development, signaling, hormone biosynthesis, regulation of gene expression, stress resistance and photoprotection. In vascular plants, violaxanthin de-epoxidase (VDE) requires ascorbate (Asc) as reductant, thereby it is required for the energy-dependent component of non-photochemical quenching (NPQ). In order to assess the role of Asc in NPQ in green algae, which are known to contain low amounts of Asc, we searched for an insertional Chlamydomonas reinhardtii mutant affected in the VTC2 gene, essential for Asc biosynthesis. The Crvtc2-1 knockout mutant was viable and, depending on the growth conditions, it contained 10 to 20% Asc relative to its wild type. When Chlamydomonas was grown photomixotrophically at moderate light, the zeaxanthin-dependent component of NPQ emerged upon strong red illumination both in the Crvtc2-1 mutant and in its wild type. Deepoxidation was unaffected by Asc deficiency, demonstrating that the Chlorophycean VDE found in Chlamydomonas does not require Asc as a reductant. The rapidly induced, energy-dependent NPQ component, characteristic of photoautotrophic Chlamydomonas cultures grown at high light, was not limited by Asc deficiency either. On the other hand, a reactive oxygen species-induced photoinhibitory NPQ component was greatly enhanced upon Asc deficiency, both under photomixotrophic and photoautotrophic conditions. These results demonstrate that Asc has distinct roles in NPQ formation in Chlamydomonas than in vascular plants.One-sentence summaryIn Chlamydomonas -in contrast to seed plants-, ascorbate is not required for violaxanthin deepoxidation and energy-dependent non-photochemical quenching but it mitigates photoinhibitory quenching.

Using Sun-induced fluorescence and Carbonyl Sulfide flux to assess the response to seasonal heatwave in a citrus orchard

2020 ◽  
Author(s):  
Amnon Cochavi ◽  
Madi Amer ◽  
Rafael Stern ◽  
Dan Yakir
Keyword(s):  
Heat Stress ◽  
Carbonyl Sulfide ◽  
Carbon Assimilation ◽  
Net Ecosystem Exchange ◽  
Pulse Amplitude ◽  
Full Scale ◽  
Photochemical Quenching ◽  
Air Temperatures ◽  
Net Assimilation ◽  
Non Photochemical Quenching

<p>Springtime heatwaves are common phenomena in the Mediterranean region, named ‘Sharav’ or ‘Hamsin’. During these heatwaves, air temperatures (Ta) and vapor pressure demand (VPD) increase rapidly over 3-5 days, followed by a dramatic drop of at least 5℃ in Ta and 1 kPa in VPD back to the pre-event values.</p><p>Here, we used our mobile lab in an irrigated lemon orchard in Rehovot, Israel to carry out eddy covariance (EC) flux measurements of net ecosystem exchange of CO<sub>2</sub> (NEE), water vapor, and carbonyl sulfide (COS), as well as canopy Sun-induced fluorescence (SIF) together with other spectral indices (NDVI, PRI, NIRv). This was supplemented with leaf-scale measurements of Pulse Amplitude modulated (PAM). Five heatwave events were detected during a two-months measurement campaign. Two other events were defined as intermediate days, with VPD values higher than normal but lower than in the full-scale heatwaves.</p><p>During both the heatwave and intermediate days, the COS fluxes (Fcos), far-red SIF, and electron transport rate (ETR), decreased during midday to the same level, compared to the control days. In contrast, NEE responded differentially between the heatwave and intermediate days, with midday values of -5.9±0.9, -3.7±0.7 and -0.69±0.62 µmol m<sup>-2</sup>s<sup>-1</sup> CO<sub>2</sub>, in the control, intermediate and heatwave days, respectively. No differences were detected in both NDVI and NIRv values. The PRI index, related to energy transfer through the non-photochemical quenching (NPQ) pathway, showed a similar pattern to that of NEE. The recovery of the ecosystem from the heatwave events was rapid and occurred within a day after the end of the events.</p><p>The results indicate a link between the far-red SIF and the ETR in the response to the heatwaves. Moreover, the reduction in far-red SIF was negatively associated with the increase in NPQ, which was reflected in both the spectral (PRI) and the PAM (NPQ value) measurements. The observed decrease in Fcos is expected to reflect a decrease in stomatal conductance to a similar extent in the heatwave and intermediate days. However, the lower rate of CO<sub>2</sub> assimilation in the full-scale heat wave days suggests that additional factors further decreased its rates beyond that limited by conductance. This can be related to the increased effect of the heat stress on other energy-demanding pathways (e.g. photorespiratory, isoprene production) that can suppress net assimilation in these days.</p><p>This work demonstrated that the relation between carbon assimilation and far-red SIF can be complex, and that combining SIF and COS measurements can help partition the effects of heat stress on conductance and other physiological effects.</p>

scholarly journals Variation in relaxation of non-photochemical quenching in a soybean nested association mapping panel as a potential source for breeding improved photosynthesis

2020 ◽  
Author(s):  
Steven J. Burgess ◽  
Elsa de Becker ◽  
Stephanie Cullum ◽  
Isla Causon ◽  
Iulia Floristeanu ◽  
...  
Keyword(s):  
Field Experiments ◽  
Genetic Manipulation ◽  
Photochemical Quenching ◽  
Low Light ◽  
Breeding Programs ◽  
Nested Association Mapping ◽  
Mapping Panel ◽  
Non Photochemical Quenching ◽  
Energy Dependent ◽  
Transgenic Manipulation

AbstractImproving the efficiency of crop photosynthesis has the potential to increase yields. Genetic manipulation showed photosynthesis can be improved in Tobacco by speeding up relaxation of photoprotective mechanisms, known as non-photochemical quenching (NPQ), during high to low light transitions. However, it is unclear if natural variation in NPQ relaxation can be exploited in crop breeding programs. To address this issue, we measured NPQ relaxation in the 41 parents of a soybean NAM population in field experiments in Illinois during 2018 and 2019. There was significant variation in amount and rate of fast, energy dependent quenching (qE) between genotypes. However, strong environmental effects led to a lack of correlation between values measured over the two growing season, and low broad-sense heritability estimates (< 0.3). These data suggest that either improvements in screening techniques, or transgenic manipulation, will be required to unlock the potential for improving the efficiency of NPQ relaxation in soybean.Table of Abbreviations

scholarly journals Photoinhibition of photosynthesis in Antarctic lichen Usnea antarctica. II. Analysis of non-photochemical quenching mechanisms activated by low to medium light doses

2014 ◽  
Vol 4 (1) ◽  
pp. 90-99 ◽  
Author(s):  
Petra Očenášová ◽  
Miloš Barták ◽  
Josef Hájek
Keyword(s):  
High Light ◽  
Photochemical Quenching ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Main Emphasis ◽  
James Ross Island ◽  
Quenching Mechanisms ◽  
Non Photochemical Quenching ◽  
Short Time ◽  
Energy Dependent

The paper focus sensitivity of an Antarctic lichen Usnea antarctica to photoinhibition studied under controlled laboratory conditions. Main emphasis was given to the analysis of quenching mechanisms, i.e. deexcitation pathways of absorbed light energy exploited in non-photochemical processes. Thalli of U. antarctica were collected at the James Ross Island, Antarctica (57°52´57´´ W, 63°48´02´´ S) and transferred in dry state to the Czech Republic. After rewetting in a laboratory, they were exposed to medium light intensities (300, 600 and 1000 mmol m-2 s-1 of photosynthetically active radiation) for 6 h. Before and during photoinhibitory treatments, chlorophyll fluorescence parameters, photoinhibitory (qI), state 1-2 transition (qT), and energy-dependent quenching (qE) in particular were measured to evaluate dose- and time-dependent changes in these parameters. The results showed that among the components forming non-photochemical quenching (qN), qI contributes to the largest extent to qN, while qE and qT contribute less. This finding differs from our earlier studies made in a short term-, and high light-treated U. antarctica that found qE together with qI is the most important part of non-photochemical quenching. Possible explanation is that photoinhibition in PS II in U. ant-arctica, when induced by low to medium light, activates qE to only limited extend and for a relatively short time (tens of minutes). With prolonged high light treatment lasting several hours, qE tends to be reduced to the values close to zero and qI then forms a major part of qN.

Dynamic responses of gas exchange and photochemistry to heat interference during drought in wheat and sorghum

2020 ◽  
Vol 47 (7) ◽  
pp. 611 ◽  
Author(s):  
Lingling Zhu ◽  
Lucas A. Cernusak ◽  
Xin Song
Keyword(s):  
Heat Stress ◽  
Gas Exchange ◽  
Crop Production ◽  
Maximum Velocity ◽  
Dynamic Responses ◽  
Future Climate Change ◽  
Photochemical Quenching ◽  
Bisphosphate Carboxylase ◽  
Non Photochemical Quenching ◽  
Drought And Heat Stress

Drought and heat stress significantly affect crop growth and productivity worldwide. It is unknown how heat interference during drought affects physiological processes dynamically in crops. Here we focussed on gas exchange and photochemistry in wheat and sorghum in response to simulated heat interference via +15°C of temperature during ~2 week drought and re-watering. Results showed that drought decreased net photosynthesis (Anet), stomatal conductance (gs), maximum velocity of ribulose-1, 5-bisphosphate carboxylase/oxygenase carboxylation (Vcmax) and electron transport rate (J) in both wheat and sorghum. Heat interference did not further reduce Anet or gs. Drought increased non-photochemical quenching (Φnpq), whereas heat interference decreased Φnpq. The δ13C of leaf, stem and roots was higher in drought-treated wheat but lower in drought-treated sorghum. The results suggest that (1) even under drought conditions wheat and sorghum increased or maintained gs for transpirational cooling to alleviate negative effects by heat interference; (2) non-photochemical quenching responded differently to drought and heat stress; (3) wheat and sorghum responded in opposing patterns in δ13C. These findings point to the importance of stomatal regulation under heat crossed with drought stress and could provide useful information on development of better strategies to secure crop production for future climate change.

Modulation of Millisecond Chlorophyll Luminescence by Non-Photochemical Fluorescence Quenching

1989 ◽  
Vol 44 (11-12) ◽  
pp. 966-970 ◽  
Author(s):  
W. Bilger ◽  
U. Schreiber
Keyword(s):  
Photosystem Ii ◽  
Fluorescence Quenching ◽  
High Frequency ◽  
Reaction Centers ◽  
Photochemical Quenching ◽  
Saturation Pulse ◽  
Induction Kinetics ◽  
Non Photochemical Quenching ◽  
Energy Dependent

Abstract By combining a high frequency modulation system for measurement of fluorescence with a phosphoroscope type apparatus for measurement of luminescence, recordings of fluorescence and luminescence induction kinetics under identical conditions were obtained. Both measuring sys­tems tolerated the application of saturating pulses of white light for rapid, transient elimination of photochemical quenching at photosystem II reaction centers, thus allowing determination of the non-photochemical quenching component. The saturation pulse induction curves of luminescence are well correlated with the corresponding curves of fluorescence, suggesting that luminescence yield is lowered by the same type of non-photochemical quenching (mostly “energy dependent quenching”) as fluorescence. Hence, in order to evaluate luminescence signals in terms of the rate of charge recombination at photosystem II reaction centers, knowledge of fluorescence quenching is required.

Mechanism of Non-Photochemical Chlorophyll Fluorescence Quenching. I. The Role of De-Epoxidised Xanthophylls and Sequestered Thylakoid Membrane Protons as Probed by Dibucaine

1995 ◽  
Vol 22 (2) ◽  
pp. 231 ◽  
Author(s):  
N Mohanty ◽  
HY Yamamoto
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Quenching ◽  
Xanthophyll Cycle ◽  
Thylakoid Membranes ◽  
Photochemical Quenching ◽  
Chlorophyll Fluorescence Quenching ◽  
Mechanism Of Inhibition ◽  
Non Photochemical Quenching ◽  
Energy Dependent

Dibucaine reportedly inhibits the light-induced transthylakoid proton gradient of chloroplasts without inhibiting energy-dependent non-photochemical chlorophyll fluorescence quenching (Laasch, H. and Weis, E. (1989). Photosynthesis Research 22, 137-146). We show that dibucaine can inhibit fluorescence quenching, depending on the de-epoxidation state of the xanthophyll cycle. Whereas dibucaine (20-40 μM) had little effect on fluorescence quenching in pre-illuminated-type thylakoids (loaded with zeaxanthin and antheraxanthin), it strongly inhibited quenching in dark-adapted-type thylakoids (no preinduction of de-epoxidation). Dibucaine inhibited lumen acidification similarly in both types of thylakoids and also the induction of violaxanthin de-epoxidation in dark-adapted thylakoids. Thus dark-adapted and pre-illuminated thylakoids differed in de-epoxidation states and their suspectibility to dibucaine inhibition of fluorescence quenching corresponded to this difference. The mechanism of inhibition of de-epoxidation by dibucaine is unclear. It could be due to the inhibition of lumen acidification but an inhibition of the violaxanthin available for de-epoxidation is not excluded. High dibucaine concentrations inhibited de-epoxidase activity directly. Dibucaine inhibition of fluorescence quenching, however, is not limited to the inhibition of de-epoxidation. Small but clear effects on fluorescence quenching were present in thylakoids even with de-epoxidation preinduced. Moreover, thylakoids with preinduced de-epoxidation were more resistant to dibucaine inhibition of fluorescene quenching when poised by salt treatments for proton partitioning into membrane-sequestered domains than when poised for proton partitioning into delocalised domains. We conclude that non-photochemical quenching of chlorophyll fluorescence depends on both de-epoxidised xanthophylls and sequestered proton domains in the thylakoid membranes

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