Phytochrome<scp>B</scp>dynamics departs from photoequilibrium in the field

Sellaro, Romina; Smith, Robert W.; Legris, Martina; Fleck, Christian; Casal, Jorge J.

doi:10.1111/pce.13445

Cited by 31 publications

(33 citation statements)

References 44 publications

(95 reference statements)

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“…Several phosphatases were shown to interact with phytochromes (Kim et al, 2002;Ryu et al, 2005;Phee et al, 2008) and furthermore phytochromes have been shown to act as autophosphorylating serine/threonine kinases. Whereas photochemical reactions are dominant under strong light, the thermal reversion rate k r1 becomes increasingly important for phyB Pfr steady-state concentrations as irradiance decreases, for example, under canopy shade, in cloudy days and/or at the extremes of the natural photoperiod (Klose et al, 2015;Sellaro et al, 2019). Our data show that these findings obtained for oat phyA are not directly conferrable to phyB.…”

Section: Researchmentioning

confidence: 51%

Differential phosphorylation of the N‐terminal extension regulates phytochrome B signaling

et al. 2019

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Summary Phytochrome B (phyB) is an excellent light quality and quantity sensor that can detect subtle changes in the light environment. The relative amounts of the biologically active photoreceptor (phyB Pfr) are determined by the light conditions and light independent thermal relaxation of Pfr into the inactive phyB Pr, termed thermal reversion. Little is known about the regulation of thermal reversion and how it affects plants’ light sensitivity. In this study we identified several serine/threonine residues on the N‐terminal extension (NTE) of Arabidopsis thaliana phyB that are differentially phosphorylated in response to light and temperature, and examined transgenic plants expressing nonphosphorylatable and phosphomimic phyB mutants. The NTE of phyB is essential for thermal stability of the Pfr form, and phosphorylation of S86 particularly enhances the thermal reversion rate of the phyB Pfr–Pr heterodimer in vivo. We demonstrate that S86 phosphorylation is especially critical for phyB signaling compared with phosphorylation of the more N‐terminal residues. Interestingly, S86 phosphorylation is reduced in light, paralleled by a progressive Pfr stabilization under prolonged irradiation. By investigating other phytochromes (phyD and phyE) we provide evidence that acceleration of thermal reversion by phosphorylation represents a general mechanism for attenuating phytochrome signaling.

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Section: Researchmentioning

confidence: 51%

Differential phosphorylation of the N‐terminal extension regulates phytochrome B signaling

et al. 2019

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“…Indeed, 2 h high-irradiance periods in the field, during which irradiance increased 10-to 30-fold and R/FR increased 10-fold, reduced the shade avoidance reactions (hypocotyl elongation) in Arabidopsis WT, but not in phyAphyB double mutants (Sellaro et al, 2011). A subsequent study (Sellaro et al, 2019) modeled the kinetics of phytochrome B conversion between its active and inactive forms, and predicted responses in hypocotyl growth to R/FR experiments, suggesting that the concentrations of active and inactive forms of phytochrome B are affected by fluctuations in irradiance. Interestingly, their experimental data ( Figure 3A in Sellaro et al, 2019) suggested that nuclear phytochrome B abundance increases with irradiance.…”

Section: Light Signaling Under Fluctuating Irradiance: a Role For Phomentioning

confidence: 88%

“…A subsequent study (Sellaro et al, 2019) modeled the kinetics of phytochrome B conversion between its active and inactive forms, and predicted responses in hypocotyl growth to R/FR experiments, suggesting that the concentrations of active and inactive forms of phytochrome B are affected by fluctuations in irradiance. Interestingly, their experimental data ( Figure 3A in Sellaro et al, 2019) suggested that nuclear phytochrome B abundance increases with irradiance. Additionally, Franklin et al (2007) showed synergistic regulation of hypocotyl elongation in response to different red irradiances by phytochromes A and B, suggesting that these photoreceptors do not only respond to changes in light quality, but also quantity.…”

Section: Light Signaling Under Fluctuating Irradiance: a Role For Phomentioning

confidence: 99%

Photosynthetic Acclimation to Fluctuating Irradiance in Plants

Morales

Kaiser

2020

Front. Plant Sci.

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Unlike the short-term responses of photosynthesis to fluctuating irradiance, the longterm response (i.e., acclimation) at the chloroplast, leaf, and plant level has received less attention so far. The ability of plants to acclimate to irradiance fluctuations and the speed at which this acclimation occurs are potential limitations to plant growth under field conditions, and therefore this process deserves closer study. In the first section of this review, we look at the sources of natural irradiance fluctuations, their effects on shortterm photosynthesis, and the interaction of these effects with circadian rhythms. This is followed by an overview of the mechanisms that are involved in acclimation to fluctuating (or changes of) irradiance. We highlight the chain of events leading to acclimation: retrograde signaling, systemic acquired acclimation (SAA), gene transcription, and changes in protein abundance. We also review how fluctuating irradiance is applied in experiments and highlight the fact that they are significantly slower than natural fluctuations in the field, although the technology to achieve realistic fluctuations exists. Finally, we review published data on the effects of growing plants under fluctuating irradiance on different plant traits, across studies, spatial scales, and species. We show that, when plants are grown under fluctuating irradiance, the chlorophyll a/b ratio and plant biomass decrease, specific leaf area increases, and photosynthetic capacity as well as root/shoot ratio are, on average, unaffected.

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“…While high, compared to low, red / far-red ratios increase the proportion of phyB in its active conformation warm temperatures have the opposite effect via thermal reversion from the active to the inactive phyB conformer. When irradiance is not high, phyB is in a steady state that depends strongly on temperature (Sellaro, Smith, Legris, Fleck & Casal 2019). The blue-light receptor phototropin (Fujii et al 2017) has also been shown to sense temperature but this photo-receptor only has a transient effect on straight stem growth (Folta & Spalding 2001).…”

Section: Introductionmentioning

confidence: 99%

Shade-avoidance responses become more aggressive in warm environments

Romero-Montepaone

Poodts

Fischbach

et al. 2019

Preprint

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AbstractWhen exposed to neighbour signals, competitive plants increase the growth of the stem to reduce the degree of current or future shade. Plants can experience similar neighbour cues under different weather conditions and the aim of this work is to investigate the impact of daily average temperature and irradiance and thermal amplitude on the magnitude of shade-avoidance responses in Arabidopsis thaliana. For this purpose, we first generated a growth database and elaborated under controlled conditions a model that predicts hypocotyl growth during the photoperiod as a function of the light-modulated activity of the main photo-sensory receptors (phytochromes A and B, cryptochromes 1 and 2), temperature-modulated activity of phytochrome B and an independent temperature input. Thermal amplitude (lower temperatures during the morning and afternoon that at midday) reduced growth of genotypes with normally fast morning growth, and this effect was incorporated to the model. Thermal amplitude also decreased the abundance of the growth-promoting transcription factor PHYTOCHROME-INTERACTING FACTOR 4. The model predicted growth in the field through different seasons with reasonable accuracy. Then, we used the model in combination with a worldwide dataset of current and future whether conditions. The analysis predicted enhanced shade-avoidance responses as a result of higher temperatures due to the geographical location or global warming. Irradiance and thermal amplitude had no effects. These trends were also observed for our local growth measurements. We conclude that, if water and nutrients do not become limiting, warm environments enhance the shade avoidance response.

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PhytochromeBdynamics departs from photoequilibrium in the field

Cited by 31 publications

References 44 publications

Differential phosphorylation of the N‐terminal extension regulates phytochrome B signaling

Differential phosphorylation of the N‐terminal extension regulates phytochrome B signaling

Photosynthetic Acclimation to Fluctuating Irradiance in Plants

Shade-avoidance responses become more aggressive in warm environments

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