| 1. |
- Kralemann, Lejon, et al.
(författare)
-
North European invasion by common ragweed is associated with early flowering and dominant changes in FT/TFL1 expression
- 2018
-
Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 69, s. 2647-2658
-
Tidskriftsartikel (refereegranskat)abstract
- During the last two centuries, the North American common ragweed (Ambrosia artemisiifolia L.) invaded a large part of the globe. Local adaptation of this species was revealed by a common garden experiment, demonstrating that the distribution of the species in Europe could extend considerably to the North. Our study compares two populations of common ragweed (one from the native range and one from the invaded range) that differ in flowering time in the wild: the invasive population flowers earlier than the native population under non-inductive long-day photoperiods. Experiments conducted in controlled environments established that the two populations differ in their flowering time even under inductive short-day photoperiods, suggesting a change in autonomous flowering control. Genetic analysis revealed that early flowering is dominantly inherited and accompanied by the increased expression of the floral activator AaFTL1 and decreased expression of the floral repressor AaFTL2. Early flowering is also accompanied by reduced reproductive output, which is evolutionarily disadvantageous under long vegetation periods. In contrast, under short vegetation periods, only early-flowering plants can produce any viable seeds, making the higher seed set of late-flowering plants irrelevant. Thus, earlier flowering appears to be a specific adaptation to the higher latitudes of northern Europe.
|
|
| 2. |
- de Jonge, Jennifer, et al.
(författare)
-
Salicylic acid interferes with GFP fluorescence in vivo
- 2017
-
Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 68, s. 1689-1696
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescent proteins have become essential tools for cell biologists. They are routinely used by plant biologists for protein and promoter fusions to infer protein localization, tissue-specific expression and protein abundance. When studying the effects of biotic stress on chromatin, we unexpectedly observed a decrease in GFP signal intensity upon salicylic acid (SA) treatment in Arabidopsis lines expressing histone H1-GFP fusions. This GFP signal decrease was dependent on SA concentration. The effect was not specific to the linker histone H1-GFP fusion but was also observed for the nucleosomal histone H2A-GFP fusion. This result prompted us to investigate a collection of fusion proteins, which included different promoters, subcellular localizations and fluorophores. In all cases, fluorescence signals declined strongly or disappeared after SA application. No changes were detected in GFP-fusion protein abundance when fluorescence signals were lost indicating that SA does not interfere with protein stability but GFP fluorescence. In vitro experiments showed that SA caused GFP fluorescence reduction only in vivo but not in vitro, suggesting that SA requires cellular components to cause fluorescence reduction. Together, we conclude that SA can interfere with the fluorescence of various GFP-derived reporter constructs in vivo. Assays that measure relocation or turnover of GFP-tagged proteins upon SA treatment should therefore be evaluated with caution.
|
|
| 3. |
- Derkacheva, Maria, et al.
(författare)
-
Arabidopsis MSI1 connects LHP1 to PRC2 complexes
- 2013
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 32, s. 2073-2085
-
Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form essential epigenetic memory systems for controlling gene expression during development in plants and animals. However, the mechanism of plant PcG protein functions remains poorly understood. Here, we probed the composition and function of plant Polycomb repressive complex 2 (PRC2). This work established the fact that all known plant PRC2 complexes contain MSI1, a homologue of Drosophila p55. While p55 is not essential for the in vitro enzymatic activity of PRC2, plant MSI1 was required for the functions of the EMBRYONIC FLOWER and the VERNALIZATION PRC2 complexes including trimethylation of histone H3 Lys27 (H3K27) at the target chromatin, as well as gene repression and establishment of competence to flower. We found that MSI1 serves to link PRC2 to LIKE HETEROCHROMATIN PROTEIN 1 (LHP1), a protein that binds H3K27me3 in vitro and in vivo and is required for a functional plant PcG system. The LHP1-MSI1 interaction forms a positive feedback loop to recruit PRC2 to chromatin that carries H3K27me3. Consequently, this can provide a mechanism for the faithful inheritance of local epigenetic information through replication.
|
|
| 4. |
- Derkacheva, Maria, et al.
(författare)
-
H2A deubiquitinases UBP12/13 are part of the Arabidopsis polycomb group protein system
- 2016
-
Ingår i: Nature Plants. - : Springer Science and Business Media LLC. - 2055-026X .- 2055-0278. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form an epigenetic memory system in plants and animals, but interacting proteins are poorly known in plants. Here, we have identified Arabidopsis UBIQUITIN SPECIFIC PROTEASES (USP; UBP in plant and yeasts) 12 and 13 as partners of the plant-specific PcG protein LIKE HETEROCHROMATIN PROTEIN 1 (LHP1). UBP12 binds to chromatin of PcG target genes and is required for histone H3 lysine 27 trimethylation and repression of a subset of PcG target genes. Plants lacking UBP12 and UBP13 developed autonomous endosperm in the absence of fertilization. We have identified UBP12 and UBP13 as new proteins in the plant PcG regulatory network. UBP12 and UBP13 belong to an ancient gene family and represent plant homologues of metazoan USP7. We have found that Drosophila USP7 shares a function in heterochromatic gene repression with UBP12/13 and their homologue UBP26. In summary, we demonstrate that USP7-like proteins are essential for gene silencing in diverse genomic contexts.
|
|
| 5. |
- Derkacheva, Maria, et al.
(författare)
-
Variations on a theme: Polycomb group proteins in plants
- 2014
-
Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 65, s. 2769-2784
-
Forskningsöversikt (refereegranskat)abstract
- Polycomb group (PcG) proteins evolved early in evolution, probably in the common ancestor of animals and plants. In some unicellular organisms, such as Chlamydomonas and Tetrahymena, PcG proteins silence genes in heterochromatin, suggesting an ancestral function in genome defence. In angiosperms, the PcG system controls many developmental transitions. A PcG function in the vernalization response evolved especially in Brassicaceaea. Thus, the role of PcG proteins has changed during evolution to match novel needs. Recent studies identified many proteins associated with plant PcG protein complexes. Possible functions of these interactions are discussed here. We highlight recent findings about recruitment of PcG proteins in plants in comparison with animal system. Through the new data, a picture emerges in which PcG protein complexes do not function in sequential linear pathways but as dynamically interacting networks allowing stabilizing feedback loops. We discuss how the interplay between different PcG protein complexes can enable establishment, maintenance, and epigenetic inheritance of H3K27me3.
|
|
| 6. |
- Dvorák Tomastíková, Eva, et al.
(författare)
-
Polycomb Repressive Complex 2 and KRYPTONITE regulate pathogen-induced programmed cell death in Arabidopsis
- 2021
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 185, s. 2003-2021
-
Tidskriftsartikel (refereegranskat)abstract
- The Polycomb Repressive Complex 2 (PRC2) is well-known for its role in controlling developmental transitions by suppressing the premature expression of key developmental regulators. Previous work revealed that PRC2 also controls the onset of senescence, a form of developmental programmed cell death (PCD) in plants. Whether the induction of PCD in response to stress is similarly suppressed by the PRC2 remained largely unknown. In this study, we explored whether PCD triggered in response to immunity- and disease-promoting pathogen effectors is associated with changes in the distribution of the PRC2-mediated histone H3 lysine 27 trimethylation (H3K27me3) modification in Arabidopsis thaliana. We furthermore tested the distribution of the heterochromatic histone mark H3K9me2, which is established, to a large extent, by the H3K9 methyltransferase KRYPTONITE, and occupies chromatin regions generally not targeted by PRC2. We report that effector-induced PCD caused major changes in the distribution of both repressive epigenetic modifications and that both modifications have a regulatory role and impact on the onset of PCD during pathogen infection. Our work highlights that the transition to pathogen-induced PCD is epigenetically controlled, revealing striking similarities to developmental PCD.
|
|
| 7. |
- Figueiredo, Duarte, et al.
(författare)
-
Auxin production in the endosperm drives seed coat development in Arabidopsis
- 2016
-
Ingår i: eLife. - 2050-084X. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- In flowering plants, seed development is initiated by the fusion of the maternal egg and central cells with two paternal sperm cells, leading to the formation of embryo and endosperm, respectively. The fertilization products are surrounded by the maternally derived seed coat, whose development prior to fertilization is blocked by epigenetic regulators belonging to the Polycomb Group (PcG) protein family. Here we show that fertilization of the central cell results in the production of auxin and most likely its export to the maternal tissues, which drives seed coat development by removing PcG function. We furthermore show that mutants for the MADS-box transcription factor AGL62 have an impaired transport of auxin from the endosperm to the integuments, which results in seed abortion. We propose that AGL62 regulates auxin transport from the endosperm to the integuments, leading to the removal of the PcG block on seed coat development.
|
|
| 8. |
- Gentry, Matthew, et al.
(författare)
-
A Structural Bisulfite Assay to Identify DNA Cruciforms
- 2016
-
Ingår i: Molecular Plant. - : Elsevier BV. - 1674-2052 .- 1752-9867. ; 9, s. 1328-1336
-
Tidskriftsartikel (refereegranskat)abstract
- In the half century since the discovery of the double-helix structure of DNA, it has become increasingly clear that DNA functionality is based on much more than its sequence in a double-helical structure. Further advances have highlighted the importance of additional aspects of DNA structure: its packaging in the higher order chromatin structure, positioning of nucleosomes along the DNA, and the occurrence of non-helical DNA structures. Of these, the latter has been problematic to prove empirically. Here, we describe a method that uses non-denaturing bisulfite sequencing on isolated Arabidopsis thaliana nuclei to determine the location of cytosines positioned outside the double helix as a result of non-B-form DNA structures. We couple this with computational methods and S1 nuclease digest to reliably identify stable, non-B-form, cruciform structures. This enables us to identify a palindrome in the promoter of FLOWERING LOCUS T that forms a stable non-B-form structure. The stronger conservation of the ability to form a non-helical secondary structure than of the sequence suggests that this structure is biologically relevant.
|
|
| 9. |
- Gentry, Matthew, et al.
(författare)
-
Remodelling chromatin to shape development of plants
- 2014
-
Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 321, s. 40-46
-
Forskningsöversikt (refereegranskat)abstract
- Establishment and dynamic regulation of a higher order chromatin structure is an essential component of development. Chromatin remodelling complexes such as the SWI2/SNF2 family of ATP-dependent chromatin remodellers can alter chromatin architecture by changing nucleosome positioning or substituting histones with histone variants. These remodellers often act in concert with chromatin modifiers such as the polycomb group proteins which confer repressive states through modification of histone tails. These mechanisms are highly conserved across the eukaryotic kingdom although in plants, owing to the maintenance of dedifferentiated cell states that allow for post-embytonic changes in development, strict control of chromatin remodelling is even more paramount. Recent and ongoing studies in the model plant Arabidopsis thaliana have found that while the major families of the SWI2/SNF2 ATPase chromatin remodellers are represented, a number of redundancies and divergent functions have emerged that show a break from the roles of their metazoan counterparts. This review focusses on the SNF2 and CHD families of ATP-dependent remodellers and their roles in plant development. (C) 2013 Elsevier Inc. All rights reserved.
|
|
| 10. |
|
|
