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Publications (10 of 34) Show all publications
Yang, Q., Blanco, N. E., Hermida-Carrera, C., Lehotai, N., Hurry, V. & Strand, Å. (2020). Two dominant boreal conifers use contrasting mechanisms to reactivate photosynthesis in the spring. Nature Communications, 11(1), Article ID 128.
Open this publication in new window or tab >>Two dominant boreal conifers use contrasting mechanisms to reactivate photosynthesis in the spring
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2020 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 11, no 1, article id 128Article in journal (Refereed) Published
Abstract [en]

Boreal forests are dominated by evergreen conifers that show strongly regulated seasonal photosynthetic activity. Understanding the mechanisms behind seasonal modulation of photosynthesis is crucial for predicting how these forests will respond to changes in seasonal patterns and how this will affect their role in the terrestrial carbon cycle. We demonstrate that the two co-occurring dominant boreal conifers, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), use contrasting mechanisms to reactivate photosynthesis in the spring. Scots pine downregulates its capacity for CO2 assimilation during winter and activates alternative electron sinks through accumulation of PGR5 and PGRL1 during early spring until the capacity for COassimilation is recovered. In contrast, Norway spruce lacks this ability to actively switch between different electron sinks over the year and as a consequence suffers severe photooxidative damage during the critical spring period.

Place, publisher, year, edition, pages
Nature Publishing Group, 2020
National Category
Forest Science Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-168976 (URN)10.1038/s41467-019-13954-0 (DOI)000512536000018 ()31913273 (PubMedID)
Available from: 2020-04-01 Created: 2020-04-01 Last updated: 2020-04-03Bibliographically approved
Blanco, N. E., Liebsch, D., Guinea Diaz, M., Strand, Å. & Whelan, J. (2019). Dual and dynamic intracellular localization of Arabidopsis thaliana SnRK1.1. Journal of Experimental Botany, 70(8), 2325-2338
Open this publication in new window or tab >>Dual and dynamic intracellular localization of Arabidopsis thaliana SnRK1.1
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2019 (English)In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, no 8, p. 2325-2338Article in journal (Refereed) Published
Abstract [en]

Sucrose non-fermenting 1 (SNF1)-related protein kinase 1.1 (SnRK1.1; also known as KIN10 or SnRK1 alpha) has been identified as the catalytic subunit of the complex SnRK1, the Arabidopsis thaliana homologue of a central integrator of energy and stress signalling in eukaryotes dubbed AMPK/Snf1/SnRK1. A nuclear localization of SnRK1.1 has been previously described and is in line with its function as an integrator of energy and stress signals. Here, using two biological models (Nicotiana benthamiana and Arabidopsis thaliana), native regulatory sequences, different microscopy techniques, and manipulations of cellular energy status, it was found that SnRK1.1 is localized dynamically between the nucleus and endoplasmic reticulum (ER). This distribution was confirmed at a spatial and temporal level by co-localization studies with two different fluorescent ER markers, one of them being the SnRK1.1 phosphorylation target HMGR. The ER and nuclear localization displayed a dynamic behaviour in response to perturbations of the plastidic electron transport chain. These results suggest that an ER-associated SnRK1.1 fraction might be sensing the cellular energy status, being a point of crosstalk with other ER stress regulatory pathways.

Place, publisher, year, edition, pages
Oxford University Press, 2019
Keywords
Arabidopsis, chloroplast, dual localization, endoplasmic reticulum (ER), ER localization, energy atus, Nicotiana benthamiana, nuclear localization, retrograde signalling, SnRK1.1
National Category
Cell Biology
Identifiers
urn:nbn:se:umu:diva-163707 (URN)10.1093/jxb/erz023 (DOI)000483170800010 ()30753728 (PubMedID)
Available from: 2019-10-16 Created: 2019-10-16 Last updated: 2019-10-16Bibliographically approved
Dubreuil, C., Jin, X., Barajas-López, J. d., Hewitt, T. C., Tanz, S. K., Dobrenel, T., . . . Strand, Å. (2018). Establishment of Photosynthesis through Chloroplast Development Is Controlled by Two Distinct Regulatory Phases. Plant Physiology, 176(2), 1199-1214
Open this publication in new window or tab >>Establishment of Photosynthesis through Chloroplast Development Is Controlled by Two Distinct Regulatory Phases
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2018 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, no 2, p. 1199-1214Article in journal (Refereed) Published
Abstract [en]

Chloroplasts develop from undifferentiated proplastids present in meristematic tissue. Thus, chloroplast biogenesis is closely connected to leaf development, which restricts our ability to study the process of chloroplast biogenesis per se. As a consequence, we know relatively little about the regulatory mechanisms behind the establishment of the photosynthetic reactions and how the activities of the two genomes involved are coordinated during chloroplast development. We developed a single cell-based experimental system from Arabidopsis (Arabidopsis thaliana) with high temporal resolution allowing for investigations of the transition from proplastids to functional chloroplasts. Using this unique cell line, we could show that the establishment of photosynthesis is dependent on a regulatory mechanism involving two distinct phases. The first phase is triggered by rapid light-induced changes in gene expression and the metabolome. The second phase is dependent on the activation of the chloroplast and generates massive changes in the nuclear gene expression required for the transition to photosynthetically functional chloroplasts. The second phase also is associated with a spatial transition of the chloroplasts from clusters around the nucleus to the final position at the cell cortex. Thus, the establishment of photosynthesis is a two-phase process with a clear checkpoint associated with the second regulatory phase allowing coordination of the activities of the nuclear and plastid genomes.

Place, publisher, year, edition, pages
American Society of Plant Biologists, 2018
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-140157 (URN)10.1104/pp.17.00435 (DOI)000424285500021 ()28626007 (PubMedID)
Projects
Bio4Energy
Available from: 2017-10-02 Created: 2017-10-02 Last updated: 2019-08-30Bibliographically approved
Guinea Diaz, M., Hernandez-Verdeja, T., Kremnev, D., Crawford, T., Dubreuil, C. & Strand, Å. (2018). Redox regulation of PEP activity during seedling establishment in Arabidopsis thaliana. Nature Communications, 9, Article ID 50.
Open this publication in new window or tab >>Redox regulation of PEP activity during seedling establishment in Arabidopsis thaliana
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2018 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 50Article in journal (Refereed) Published
Abstract [en]

Activation of the plastid-encoded RNA polymerase is tightly controlled and involves a network of phosphorylation and, as yet unidentified, thiol-mediated events. Here, we characterize PLASTID REDOX INSENSITIVE2, a redox-regulated protein required for full PEP-driven transcription. PRIN2 dimers can be reduced into the active monomeric form by thioredoxins through reduction of a disulfide bond. Exposure to light increases the ratio between the monomeric and dimeric forms of PRIN2. Complementation of prin2-2 with different PRIN2 protein variants demonstrates that the monomer is required for light-activated PEP-dependent transcription and that expression of the nuclear-encoded photosynthesis genes is linked to the activity of PEP. Activation of PEP during chloroplast development likely is the source of a retrograde signal that promotes nuclear LHCB expression. Thus, regulation of PRIN2 is the thiol-mediated mechanism required for full PEP activity, with PRIN2 monomerization via reduction by TRXs providing a mechanistic link between photosynthetic electron transport and activation of photosynthetic gene expression.

National Category
Other Biological Topics
Identifiers
urn:nbn:se:umu:diva-144086 (URN)10.1038/s41467-017-02468-2 (DOI)000419308300001 ()29298981 (PubMedID)
Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2018-06-09Bibliographically approved
Hernandez-Verdeja, T. & Strand, Å. (2018). Retrograde Signals Navigate the Path to Chloroplast Development. Plant Physiology, 176(2), 967-976
Open this publication in new window or tab >>Retrograde Signals Navigate the Path to Chloroplast Development
2018 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, no 2, p. 967-976Article in journal (Refereed) Published
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-145152 (URN)10.1104/pp.17.01299 (DOI)000424285500002 ()29254985 (PubMedID)
Available from: 2018-03-02 Created: 2018-03-02 Last updated: 2018-06-09Bibliographically approved
Dubreuil, C., Ji, Y., Strand, Å. & Grönlund, A. (2017). A quantitative model of the phytochrome-PIF light signalling initiating chloroplast development. Scientific Reports, 7, Article ID 13884.
Open this publication in new window or tab >>A quantitative model of the phytochrome-PIF light signalling initiating chloroplast development
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 13884Article in journal (Refereed) Published
Abstract [en]

The components required for photosynthesis are encoded in two separate genomes, the nuclear and the plastid. To address how synchronization of the two genomes involved can be attained in early light-signalling during chloroplast development we have formulated and experimentally tested a mathematical model simulating light sensing and the following signalling response. The model includes phytochrome B (PhyB), the phytochrome interacting factor 3 (PIF3) and putative regulatory targets of PIF3. Closed expressions of the phyB and PIF3 concentrations after light exposure are derived, which capture the relevant timescales in the response of genes regulated by PIF3. Sequence analysis demonstrated that the promoters of the nuclear genes encoding sigma factors (SIGs) and polymerase-associated proteins (PAPs) required for expression of plastid encoded genes, contain the cis-elements for binding of PIF3. The model suggests a direct link between light inputs via PhyB-PIF3 to the plastid transcription machinery and control over the expression of photosynthesis components both in the nucleus and in the plastids. Using a pluripotent Arabidopsis cell culture in which chloroplasts develop from undifferentiated proplastids following exposure to light, we could experimentally verify that the expression of SIGs and PAPs in response to light follow the calculated expression of a PhyB-PIF3 regulated gene.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Botany Developmental Biology
Identifiers
urn:nbn:se:umu:diva-141809 (URN)10.1038/s41598-017-13473-2 (DOI)000413597800001 ()29066729 (PubMedID)
Available from: 2017-11-27 Created: 2017-11-27 Last updated: 2018-06-09Bibliographically approved
Razzak, A., Ranade, S. S., Strand, Å. & Garcia-Gil, M. R. (2017). Differential response of Scots pine seedlings to variable intensity and ratio of red and far-red light. Plant, Cell and Environment, 40(8), 1332-1340
Open this publication in new window or tab >>Differential response of Scots pine seedlings to variable intensity and ratio of red and far-red light
2017 (English)In: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 40, no 8, p. 1332-1340Article in journal (Refereed) Published
Abstract [en]

We investigated the response to increasing intensity of red (R) and far-R (FR) light and to a decrease in R: FR ratio in Pinus sylvestris L. (Scots pine) seedling. The results showed that FR high-irradiance response for hypocotyl elongation may be present in Scots pine and that this response is enhanced by increasing light intensity. However, both hypocotyl inhibition and pigment accumulation were more strongly affected by the R light compared with FR light. This is in contrast to previous reports in Arabidopsis thaliana (L.) Heynh. In the angio-sperm, A. thaliana R light shows an overall milder effect on inhibition of hypocotyl elongation and on pigment biosynthesis compared with FR suggesting conifers and angiosperms respond very differently to the different light regimes. Scots pine shade avoidance syndrome with longer hypocotyls, shorter cotyledons and lower chlorophyll content in response to shade conditions resembles the response observed in A. thaliana. However, anthocyanin accumulation increased with shade in Scots pine, which again differs from what is known in angiosperms. Overall, the response of seedling development and physiology to R and FR light in Scots pine indicates that the regulatory mechanism for light response may differ between gymnosperms and angiosperms.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
light intensity, light quality, R:FR ratio, shade avoidance syndrome, seedling morphology, pigment synthesis
National Category
Zoology Botany
Identifiers
urn:nbn:se:umu:diva-137934 (URN)10.1111/pce.12921 (DOI)000405275300008 ()
Available from: 2017-08-02 Created: 2017-08-02 Last updated: 2018-06-09Bibliographically approved
Norén, L., Kindgren, P., Stachula, P., Rühl, M., Eriksson, M. E., Hurry, V. & Strand, Å. (2016). Circadian and Plastid Signaling Pathways Are Integrated to Ensure Correct Expression of the CBF and COR Genes during Photoperiodic Growth. Plant Physiology, 171(2), 1392-1406
Open this publication in new window or tab >>Circadian and Plastid Signaling Pathways Are Integrated to Ensure Correct Expression of the CBF and COR Genes during Photoperiodic Growth
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2016 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 171, no 2, p. 1392-1406Article in journal (Refereed) Published
Abstract [en]

The circadian clock synchronizes a wide range of biological processes with the day/night cycle, and correct circadian regulation is essential for photosynthetic activity and plant growth. We describe here a mechanism where a plastid signal converges with the circadian clock to fine-tune the regulation of nuclear gene expression in Arabidopsis (Arabidopsis thaliana). Diurnal oscillations of tetrapyrrole levels in the chloroplasts contribute to the regulation of the nucleus-encoded transcription factors C-REPEAT BINDING FACTORS (CBFs). The plastid signal triggered by tetrapyrrole accumulation inhibits the activity of cytosolic HEAT SHOCK PROTEIN90 and, as a consequence, the maturation and stability of the clock component ZEITLUPE (ZTL). ZTL negatively regulates the transcription factor LONG HYPOCOTYL5 (HY5) and PSEUDO-RESPONSE REGULATOR5 (PRR5). Thus, low levels of ZTL result in a HY5- and PRR5-mediated repression of CBF3 and PRR5-mediated repression of CBF1 and CBF2 expression. The plastid signal thereby contributes to the rhythm of CBF expression and the downstream COLD RESPONSIVE expression during day/night cycles. These findings provide insight into how plastid signals converge with, and impact upon, the activity of well-defined clock components involved in circadian regulation.

National Category
Botany
Identifiers
urn:nbn:se:umu:diva-125464 (URN)10.1104/pp.16.00374 (DOI)000380699200048 ()27208227 (PubMedID)
Available from: 2016-09-12 Created: 2016-09-12 Last updated: 2018-06-07Bibliographically approved
Kindgren, P. & Strand, Å. (2015). Chloroplast transcription, untangling the Gordian Knot. New Phytologist, 206(3), 889-891
Open this publication in new window or tab >>Chloroplast transcription, untangling the Gordian Knot
2015 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 206, no 3, p. 889-891Article in journal, Editorial material (Other academic) Published
Keywords
chloroplast, development, plastid encoded RNA polymerase (PEP), polymerase-associated protein AP), pTAC, plastome
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-103196 (URN)10.1111/nph.13388 (DOI)000352802800003 ()25865165 (PubMedID)
Available from: 2015-05-29 Created: 2015-05-18 Last updated: 2018-06-07Bibliographically approved
Kindgren, P., Dubreuil, C. & Strand, Å. (2015). The Recovery of Plastid Function Is Required for Optimal Response to Low Temperatures in Arabidopsis. PLoS ONE, 10(9), Article ID e0138010.
Open this publication in new window or tab >>The Recovery of Plastid Function Is Required for Optimal Response to Low Temperatures in Arabidopsis
2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 9, article id e0138010Article in journal (Refereed) Published
Abstract [en]

Cold acclimation is an essential response in higher plants to survive freezing temperatures. Here, we report that two independent mutant alleles of the H-subunit of Mg-chelatase, CHLH, gun5-1 and cch in Arabidopsis are sensitive to low temperatures. Plants were grown in photoperiodic conditions and exposed to low temperatures for short-and long-term periods. Tetrapyrrole biosynthesis was initially significantly inhibited in response to low temperature but recovered in wild type (Col-0), although the tetrapyrrole levels were lower in cold compared to control conditions. The gun5-1 and cch alleles showed an inability to recover chlorophyll biosynthesis in addition to a significant decrease in freezing tolerance. We found that the impaired plastid function in the CHLH mutant plants resulted in compromised de novo protein synthesis at low temperatures. The expression of the transcription factors CBF1-3 was super-induced in gun5-1 and cch mutant alleles but expression levels of their target genes, COR15a, COR47 and COR78 were similar or even lower compared to Col-0. In addition, the protein levels of COR15a were lower in gun5-1 and cch and a general defect in protein synthesis could be seen in the gun5-1 mutant following a 35S labelling experiment performed at low temperature. Taken together, our results demonstrate the importance of a functional chloroplast for the cold acclimation process and further suggest that impaired plastid function could result in inhibition of protein synthesis at low temperature.

National Category
Genetics
Identifiers
urn:nbn:se:umu:diva-110200 (URN)10.1371/journal.pone.0138010 (DOI)000361601100202 ()
Available from: 2015-10-20 Created: 2015-10-16 Last updated: 2018-06-07Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6664-0471

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