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Dubreuil, Carole
Publications (6 of 6) Show all publications
Dubreuil, C., Jin, X., Grönlund, A. & Fischer, U. (2018). A local auxin gradient regulates root cap self-renewal and size homeostasis. Current Biology, 28(16), 2581-+
Open this publication in new window or tab >>A local auxin gradient regulates root cap self-renewal and size homeostasis
2018 (English)In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 28, no 16, p. 2581-+Article in journal (Refereed) Published
Abstract [en]

Organ size homeostasis, compensatory growth to replace lost tissue, requires constant measurement of size and adjustment of growth rates. Morphogen gradients control organ and tissue sizes by regulating stem cell activity, cell differentiation, and removal in animals [1-3]. In plants, control of tissue size is of specific importance in root caps to protect the growing root tip from mechanical damage [4]. New root cap tissue is formed by the columella and lateral root-cap-epidermal stem cells, whose activity is regulated through non-dividing niche-like cells, the quiescent center (QC) [4, 5]. Columella daughter cells in contact with the QC retain the potency to divide, while derivatives oriented toward the mature cap undergo differentiation. The outermost columella layers are sequentially separated from the root body, involving remodeling of cell walls [6]. Factors regulating the balance between cell division, elongation, and separation to keep root cap size constant are currently unknown [4]. Here, we report that stem cell proliferation induced cell separation at the periphery of the root cap, resulting in tissue size homeostasis. An auxin response gradient with a maximum in the QC and a minimum in the detaching layer was established prior to the onset of cell separation. In agreement with a mathematical model, tissue size was positively regulated by the amount of auxin released from the source. Auxin transporters localized non-polarly to plasma membranes of the inner cap, partly isolating separating layers from the auxin source. Together, these results are in support of an auxin gradient measuring and regulating tissue size.

Place, publisher, year, edition, pages
Cell Press, 2018
National Category
Developmental Biology
urn:nbn:se:umu:diva-151556 (URN)10.1016/j.cub.2018.05.090 (DOI)000442111300027 ()30078563 (PubMedID)
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-09-10Bibliographically 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
urn:nbn:se:umu:diva-140157 (URN)10.1104/pp.17.00435 (DOI)000424285500021 ()28626007 (PubMedID)
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
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
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
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
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
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
Kremnev, D., Guinea Diaz, M., Dubreuil, C. & Strand, Å. Redox regulation of PEP activity during seedling development in Arabidopsis.
Open this publication in new window or tab >>Redox regulation of PEP activity during seedling development in Arabidopsis
(English)Manuscript (preprint) (Other academic)
National Category
Biochemistry and Molecular Biology
urn:nbn:se:umu:diva-96176 (URN)
Available from: 2014-11-11 Created: 2014-11-11 Last updated: 2018-06-07Bibliographically approved

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