Xanthophyll Cycle Activity in Two Prominent Arctic Shrub Species

Magney, Troy S.; Logan, Barry A.; Reblin, Jaret S.; Boelman, Natalie T.; Eitel, Jan U. H.; Greaves, Heather E.; Griffin, Kevin L.; Prager, Case M.; Vierling, Lee A.

doi:10.1657/aaar0016-044

Cited by 11 publications

(11 citation statements)

References 72 publications

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“…Additionally, if leaves with higher rates of sustained NPQ (more stressed) were included in this study we would expect to see a larger variation in PC3 in Figure , and a greater change in ChlF magnitude. The NPQ related spectral shape shift would also be greater if primarily sun‐exposed leaves, which are known to have higher xanthophyll cycle pools and NPQ rates (Magney, Logan, et al, ; Niinemets, ), were sampled. Nonetheless, it is remarkable that even at steady state, the SVD analysis is able to capture a tertiary component of variance, despite the relatively small influence this has on the overall spectrum.…”

Section: Discussionmentioning

confidence: 99%

Disentangling Changes in the Spectral Shape of Chlorophyll Fluorescence: Implications for Remote Sensing of Photosynthesis

et al. 2019

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Novel satellite measurements of solar‐induced chlorophyll fluorescence (SIF) can improve our understanding of global photosynthesis; however, little is known about how to interpret the controls on its spectral variability. To address this, we disentangle simultaneous drivers of fluorescence spectra by coupling active and passive fluorescence measurements with photosynthesis. We show empirical and mechanistic evidence for where, why, and to what extent leaf fluorescence spectra change. Three distinct components explain more than 95% of the variance in leaf fluorescence spectra under both steady‐state and changing illumination conditions. A single spectral shape of fluorescence explains 84% of the variance across a wide range of species. The magnitude of this shape responds to absorbed light and photosynthetic up/down regulation; meanwhile, chlorophyll concentration and nonphotochemical quenching control 9% and 3% of the remaining spectral variance, respectively. The spectral shape of fluorescence is remarkably stable where most current satellite retrievals occur (“far‐red,” >740nm), and dynamic downregulation of photosynthesis reduces fluorescence magnitude similarly across the 670‐ to 850‐nm range. We conduct an exploratory analysis of hourly red and far‐red canopy SIF in soybean, which shows a subtle change in red:far‐red fluorescence coincident with photosynthetic downregulation but is overshadowed by longer‐term changes in canopy chlorophyll and structure. Based on our leaf and canopy analysis, caution should be taken when attributing large changes in the spectral shape of remotely sensed SIF to plant stress, particularly if data acquisition is temporally sparse. Ultimately, changes in SIF magnitude at wavelengths greater than 740 nm alone may prove sufficient for tracking photosynthetic dynamics.

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Section: Discussionmentioning

confidence: 99%

Disentangling Changes in the Spectral Shape of Chlorophyll Fluorescence: Implications for Remote Sensing of Photosynthesis

et al. 2019

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“…Photo-protection can also take place through controlled heat dissipation (i.e. non-photochemical quenching, NPQ), which is correlated to the amount of xanthophyll cycle pigments and to the de-epoxidation ratio of zea-to violaxanthin (Harker et al 1999, Magney et al 2017. The relative concentration of xanthophylls increased with in creasing temperature, and the de-epoxidation ratio increased substantially in algae exposed to 21 and 24°C during the HW.…”

Section: Discussionmentioning

confidence: 99%

Exposure to simulated heatwave scenarios causes long-term reductions in performance in Saccharina latissima

Nepper-Davidsen¹,

Andersen²,

Pedersen³

2019

Mar. Ecol. Prog. Ser.

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Kelps are important foundation species in many cold-temperate coastal systems, and the loss of these organisms is a threat to ecosystem structure and function. The abundance of sugar kelp Saccharina latissima has recently declined in Northern Europe, which has been explained by increasing water temperature. We tested heat tolerance of sugar kelp exposed to simulated heatwave scenarios of 15, 18, 21 and 24°C for 3 wk, followed by a 2 wk recovery period at 15°C. Growth rate and photosynthetic performance decreased significantly with increasing temperature, while mortality remained low among treatments except at 24°C, where > 90% of the algae died within a few days. Although exposure to 18 and 21°C had limited effect on mortality, kelps exposed to these temperatures had negative growth and continued to show impaired photosynthesis during the subsequent recovery period. Reductions in growth were strongly correlated to reduced carbon acquisition and, hence, photosynthetic performance, which was strongly correlated to heat-related changes in pigmentation. We suggest that reduced performance after exposure to elevated but non-lethal temperatures was caused by oxidative stress resulting from a discrepancy between light absorption and photosynthesis. Our results show that exposure to high but sub-lethal temperatures can have significant long-term effects, which may cause loss of biomass and leave sugar kelp susceptible to other stressors.

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“…When computing the EMM it is important to consider the spectral shape of the illumination source and the actual number of photons absorbed by the chloroplast (aPAR). Additionally, interpretation of the results could be further improved by including data on plant pigments, where we could observe changes in xanthophyll cycle pigment concentrations under illumination (similar to Magney et al, 2017), permitting better characterization of the interactions among leaf pigment concentrations (particularly Chl) and leaf morphology to better understand the biophysical contributions of fluoresced photons.…”

Section: Discussionmentioning

confidence: 99%

Connecting active to passive fluorescence with photosynthesis: a method for evaluating remote sensing measurements of Chl fluorescence

et al. 2017

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Recent advances in the retrieval of Chl fluorescence from space using passive methods (solar-induced Chl fluorescence, SIF) promise improved mapping of plant photosynthesis globally. However, unresolved issues related to the spatial, spectral, and temporal dynamics of vegetation fluorescence complicate our ability to interpret SIF measurements. We developed an instrument to measure leaf-level gas exchange simultaneously with pulse-amplitude modulation (PAM) and spectrally resolved fluorescence over the same field of view - allowing us to investigate the relationships between active and passive fluorescence with photosynthesis. Strongly correlated, slope-dependent relationships were observed between measured spectra across all wavelengths (F , 670-850 nm) and PAM fluorescence parameters under a range of actinic light intensities (steady-state fluorescence yields, F ) and saturation pulses (maximal fluorescence yields, F ). Our results suggest that this method can accurately reproduce the full Chl emission spectra - capturing the spectral dynamics associated with changes in the yields of fluorescence, photochemical (ΦPSII), and nonphotochemical quenching (NPQ). We discuss how this method may establish a link between photosynthetic capacity and the mechanistic drivers of wavelength-specific fluorescence emission during changes in environmental conditions (light, temperature, humidity). Our emphasis is on future research directions linking spectral fluorescence to photosynthesis, ΦPSII, and NPQ.

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Xanthophyll Cycle Activity in Two Prominent Arctic Shrub Species

Cited by 11 publications

References 72 publications

Disentangling Changes in the Spectral Shape of Chlorophyll Fluorescence: Implications for Remote Sensing of Photosynthesis

Disentangling Changes in the Spectral Shape of Chlorophyll Fluorescence: Implications for Remote Sensing of Photosynthesis

Exposure to simulated heatwave scenarios causes long-term reductions in performance in Saccharina latissima

Connecting active to passive fluorescence with photosynthesis: a method for evaluating remote sensing measurements of Chl fluorescence

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