Fine tuning chloroplast movements through physical interactions between phototropins

Sztatelman, Olga; Łabuz, Justyna; Hermanowicz, Paweł; Banaś, Agnieszka Katarzyna; Bażant, Aneta; Zgłobicki, Piotr; Aggarwal, Chhavi; Nadzieja, Marcin; Krzeszowiec, Weronika; Strzałka, Wojciech; Gabryś, Halina

doi:10.1093/jxb/erw265

Cited by 26 publications

(45 citation statements)

References 52 publications

(105 reference statements)

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“…7). Partial defect in the avoidance response in the phot1 mutant was reported also in other studies (Luesse et al, 2010;Sztatelman et al, 2016). No detectable light-induced changes in leaf transmittance were observed in the phot1phot2 mutants ( Fig.…”

Section: Chloroplast Outer Membrane-associated Phot2 Induced the Chlosupporting

confidence: 86%

Phototropin2 Contributes to the Chloroplast Avoidance Response at the Chloroplast-Plasma Membrane Interface

et al. 2020

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Blue-light-induced chloroplasts movements play an important role in maximizing light utilization for photosynthesis in plants. Under a weak light condition, chloroplasts accumulate to the cell surface to capture light efficiently (chloroplast accumulation response). Conversely, chloroplasts escape from strong light and move to the side wall to reduce photodamage (chloroplast avoidance response). The blue light receptor phototropin (phot) regulates these chloroplast movements and optimizes leaf photosynthesis by controlling other responses as well as chloroplast movements. Seed plants such as Arabidopsis thaliana have the phototropins phot1 and phot2. They redundantly mediate phototropism, stomatal opening, leaf flattening, and the chloroplast accumulation response. However, the chloroplast avoidance response is induced by strong blue light and regulated primarily by phot2. Phototropins are localized mainly on the plasma membrane. However, a substantial amount of phot2 resides on the chloroplast outer envelope. Therefore, differentially localized phot2 might have different functions. To determine the functions of plasma membrane-and chloroplast envelope-localized phot2, we tethered it to these structures with their respective targeting signals. Plasma membrane-localized phot2 regulated phototropism, leaf flattening, stomatal opening, and chloroplast movements. Chloroplast envelope-localized phot2 failed to mediate phototropism, leaf flattening, and the chloroplast accumulation response but partially regulated the chloroplast avoidance response and stomatal opening. Based on the present and previous findings, we propose that phot2 localized at the interface between the plasma membrane and the chloroplasts is required for the chloroplast avoidance response and possibly for stomatal opening as well.

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Section: Chloroplast Outer Membrane-associated Phot2 Induced the Chlosupporting

confidence: 86%

Phototropin2 Contributes to the Chloroplast Avoidance Response at the Chloroplast-Plasma Membrane Interface

et al. 2020

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“…Previous studies revealed that the transitional light intensity in the Atphot1 mutant is similar to that in WT plants, suggesting that Atphot2 mainly controls the transitional light intensity in A. thaliana [31,32]. In addition, the transitional light intensity between the accumulation and avoidance responses is lowered by an engineered Atphot2 with a long-lifetime of the photoactivated state [33].…”

Section: Plos Onementioning

confidence: 89%

“…Notably, cold treatment had a more significant effect on the decrease of Atphot1 levels than the increase of Atphot2 levels [16], implying that the expression of Atphot1 might be more sensitive to cold than that of Atphot2. Previous studies indicated that Atphot1 and Atphot2 have the high and low activities, respectively, to induce the accumulation response in A. thaliana [31,32]. In this context, the cold-induced decrease of Atphot1 levels may contribute rapid physiological change from the accumulation response to cold-avoidance response in A. thaliana.…”

Section: Alteration Of Phot Expression Is Not Required For Induction mentioning

confidence: 95%

The cold-induced switch in direction of chloroplast relocation occurs independently of changes in endogenous phototropin levels

et al. 2020

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When exposed to fluctuating light intensity, chloroplasts move towards weak light (accumulation response), and away from strong light (avoidance response). In addition, cold treatment (5˚C) induces the avoidance response even under weak-light conditions (coldavoidance response). These three responses are mediated by the phototropin (phot), which is a blue-light photoreceptor and has also been reported to act as a thermosensory protein that perceives temperature variation. Our previous report indicated that cold-induced changes in phot biochemical activity initiate the cold-avoidance response. In this study, we further explored the induction mechanism of the cold-avoidance response in the liverwort Marchantia polymorpha and examined the relationship between changes in the amount of phot and the induction of the cold-avoidance response. The switch between the accumulation and avoidance responses occurs at a so-called 'transitional' light intensity. Our physiological experiments revealed that a cold-mediated decrease in the transitional light intensity leads to the induction of the cold-avoidance response. While artificial overexpression of phot decreased the transitional light intensity as much as cold treatment did, the amount of endogenous phot was not increased by cold treatment in wild-type M. polymorpha. Taken together, these findings show that the cold-avoidance response is initiated by a cold-mediated reduction of the transitional light intensity, independent of the amount of endogenous phot. This study provides a clue to understanding the mechanism underlying the switch in direction of chloroplast relocation in response to light and temperature.

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“…An attempt was made to compare the BrachPHOT1 and BrachPHOT2 mRNA levels with the protein levels evaluated by western blot. We used antibodies for Arabidopsis Anti-PHOT1 (AS10 720) and anti-PHOT2 (AS10 721) purchased from (Agrisera), detailed information in Łabuz et al ( 2015 ) and Sztatelman et al ( 2016 ). The experiment was repeated several times.…”

Section: Methodsmentioning

confidence: 99%

Chloroplasts in C3 grasses move in response to blue-light

2020

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Key message Brachypodium distachyonis a good model for studying chloropla st movements in the crop plants, wheat, rye and barley. The movements are activated only by blue light, similar to Arabidopsis. Abstract Chloroplast translocations are ubiquitous in photosynthetic organisms. On the one hand, they serve to optimize energy capture under limiting light, on the other hand, they minimize potential photodamage to the photosynthetic apparatus in excess light. In higher plants chloroplast movements are mediated by phototropins (phots), blue light receptors that also control other light acclimation responses. So far, Arabidopsis thaliana has been the main model for studying the mechanism of blue light signaling to chloroplast translocations in terrestrial plants. Here, we propose Brachypodium distachyon as a model in research into chloroplast movements in C3 cereals. Brachypodium chloroplasts respond to light in a similar way to those in Arabidopsis. The amino acid sequence of Brachypodium PHOT1 is 79.3% identical, and that of PHOT2 is 73.6% identical to the sequence of the corresponding phototropin in Arabidopsis. Both phototropin1 and 2 are expressed in Brachypodium, as shown using quantitative real-time PCR. Intriguingly, the light-expression pattern of BradiPHOT1 and BradiPHOT2 is the opposite of that for Arabidopsis phototropins, suggesting potential unique light signaling in C3 grasses. To investigate if Brachypodium is a good model for studying grass chloroplast movements we analyzed these movements in the leaves of three C3 crop grasses, namely wheat, rye and barley. Similarly to Brachypodium, chloroplasts only respond to blue light in all these species.

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Fine tuning chloroplast movements through physical interactions between phototropins

Abstract: HighlightPhysical interactions between phototropin molecules can alter their signaling outcomes, providing the means for the plant to fine-tune its blue light responses.

Cited by 26 publications

References 52 publications

Phototropin2 Contributes to the Chloroplast Avoidance Response at the Chloroplast-Plasma Membrane Interface

Phototropin2 Contributes to the Chloroplast Avoidance Response at the Chloroplast-Plasma Membrane Interface

The cold-induced switch in direction of chloroplast relocation occurs independently of changes in endogenous phototropin levels

Chloroplasts in C3 grasses move in response to blue-light

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