| 1. |
- Bai, Bing, et al.
(author)
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Seed-Stored mRNAs that Are Specifically Associated to Monosomes Are Translationally Regulated during Germination
- 2020
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In: Plant Physiology. - Rockville : American Society for Plant Biologists. - 0032-0889 .- 1532-2548. ; 182:1, s. 378-392
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Journal article (peer-reviewed)abstract
- The life cycle of many organisms includes a quiescent stage, such as bacterial or fungal spores, insect larvae, or plant seeds. Common to these stages is their low water content and high survivability during harsh conditions. Upon rehydration, organisms need to reactivate metabolism and protein synthesis. Plant seeds contain many mRNAs that are transcribed during seed development. Translation of these mRNAs occurs during early seed germination, even before the requirement of transcription. Therefore, stored mRNAs are postulated to be important for germination. How these mRNAs are stored and protected during long-term storage is unknown. The aim of this study was to investigate how mRNAs are stored in dry seeds and whether they are indeed translated during seed germination. We investigated seed polysome profiles and the mRNAs and protein complexes that are associated with these ribosomes in seeds of the model organism Arabidopsis (Arabidopsis thaliana). We showed that most stored mRNAs are associated with monosomes in dry seeds; therefore, we focus on monosomes in this study. Seed ribosome complexes are associated with mRNA-binding proteins, stress granule, and P-body proteins, which suggests regulated packing of seed mRNAs. Interestingly, similar to 17% of the mRNAs that are specifically associated with monosomes are translationally up-regulated during seed germination. These mRNAs are transcribed during seed maturation, suggesting a role for this developmental stage in determining the translational fate of mRNAs during early germination.
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| 2. |
- Bai, Bing, et al.
(author)
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SeedTransNet : a directional translational network revealing regulatory patterns during seed maturation and germination
- 2023
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In: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 74:7, s. 2416-2432
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Journal article (peer-reviewed)abstract
- Seed maturation is the developmental process that prepares the embryo for the desiccated waiting period before germination. It is associated with a series of physiological changes leading to the establishment of seed dormancy, seed longevity, and desiccation tolerance. We studied translational changes during seed maturation and observed a gradual reduction in global translation during seed maturation. Transcriptome and translatome profiling revealed specific reduction in the translation of thousands of genes. By including previously published data on germination and seedling establishment, a regulatory network based on polysome occupancy data was constructed: SeedTransNet. Network analysis predicted translational regulatory pathways involving hundreds of genes with distinct functions. The network identified specific transcript sequence features suggesting separate translational regulatory circuits. The network revealed several seed maturation-associated genes as central nodes, and this was confirmed by specific seed phenotypes of the respective mutants. One of the regulators identified, an AWPM19 family protein, PM19-Like1 (PM19L1), was shown to regulate seed dormancy and longevity. This putative RNA-binding protein also affects the translational regulation of its target mRNA, as identified by SeedTransNet. Our data show the usefulness of SeedTransNet in identifying regulatory pathways during seed phase transitions.
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| 3. |
- Bentsink, Leónie, et al.
(author)
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Natural variation for seed dormancy in Arabidopsis is regulated by additive genetic and molecular pathways
- 2010
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In: Proceedings of the National Academy of Sciences of the United States of America. - : PNAS. - 0027-8424 .- 1091-6490. ; 107:9, s. 4264-4269
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Journal article (peer-reviewed)abstract
- Timing of germination is presumably under strong natural selection as it determines the environmental conditions in which a plant germinates and initiates its postembryonic life cycle. To investigate how seed dormancy is controlled, quantitative trait loci (QTL) analyses has been performed in six Arabidopsis thaliana recombinant inbred line populations by analyzing them simultaneously using a mixed model QTL approach. The recombinant inbred line populations were derived from crosses between the reference accession Landsberg erecta (Ler) and accessions from different world regions. In total, 11 delay of germination (DOG) QTL have been identified, and nine of them have been confirmed by near isogenic lines (NILs). The absence of strong epistatic interactions between the different DOG loci suggests that they affect dormancy mainly by distinct genetic pathways. This was confirmed by analyzing the transcriptome of freshly harvested dry seeds of five different DOG NILs. All five DOG NILs showed discernible and different expression patterns compared with the expression of their genetic background Ler. The genes identified in the different DOG NILs represent largely different gene ontology profiles. It is proposed that natural variation for seed dormancy in Arabidopsis is mainly controlled by different additive genetic and molecular pathways rather than epistatic interactions, indicating the involvement of several independent pathways.
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| 4. |
- Hanson, Johannes, 1969-, et al.
(author)
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Sugar-dependent alterations in cotyledon and leaf development in transgenic plants expressing the HDZhdip gene ATHB13
- 2001
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In: Plant Molecular Biology. - : Kluwer Academic Publishers. - 0167-4412 .- 1573-5028. ; 45:3, s. 247-262
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Journal article (peer-reviewed)abstract
- ATHB13 is a new member of the homeodomain leucine zipper (HDZip) transcription factor family of Arabidopsis thaliana. Constitutive high-level expression of the ATHB13 cDNA in transgenic plants results in altered development of cotyledons and leaves, specifically in plants grown on media containing metabolizable sugars. Cotyledons and leaves of sugar-grown transgenic plants are more narrow and the junction between the petiole and the leaf blade less distinct, as compared to the wild type. High-level expression of ATHB13 affects cotyledon shape by inhibiting lateral expansion of epidermal cells in sugar-treated seedlings. Experiments with non-metabolizable sugars indicate that the alteration in leaf shape in the ATHB13 transgenics is mediated by sucrose sensing. ATHB13 further affects a subset of the gene expression responses of the wild-type plant to sugars. The expression of genes encoding beta-amylase and vegetative storage protein is induced to higher levels in response to sucrose in the transgenic plants as compared to the wild type. The expression of other sugar-regulated genes examined is unaffected by ATHB13. These data suggest that ATHB13 may be a component of the sucrose-signalling pathway, active close to the targets of the signal transduction.
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| 5. |
- Hanson, Johannes, 1969-, et al.
(author)
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Sugar perception and signaling : an update
- 2009
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In: Current opinion in plant biology. - : Elsevier. - 1369-5266 .- 1879-0356. ; 12:5, s. 562-567
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Journal article (peer-reviewed)abstract
- Sugars act as potent signaling molecules in plants. Several sugar sensors, including the highly studied glucose sensor HEXOKINASE1 (HXK1), have been identified or proposed. Many additional sensors likely exist, as plants respond to other sugars and sugar metabolites, such as sucrose and trehalose 6-phosphate. Sugar sensing and signaling is a highly complex process resulting in many changes in physiology and development and is integrated with other signaling pathways in plants such as those for inorganic nutrients, hormones, and different stress factors. Importantly, KIN10 and KIN11 protein kinases are central in coordinating several of the responses to sugars and stress. bZIP transcription factors were found to mediate effects of sugar signaling on gene expression and metabolite content.
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| 6. |
- Hanson, Johannes, 1969-, et al.
(author)
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The sucrose regulated transcription factor bZIP11 affects amino acid metabolism by regulating the expression of ASPARAGINE SYNTHETASE1 and PROLINE DEHYDROGENASE2
- 2008
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In: The Plant Journal. - : John Wiley & Sons. - 0960-7412 .- 1365-313X. ; 53:6, s. 935-949
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Journal article (peer-reviewed)abstract
- Translation of the transcription factor bZIP11 is repressed by sucrose in a process that involves a highly conserved peptide encoded by the 5' leaders of bZIP11 and other plant basic region leucine zipper (bZip) genes. It is likely that a specific signaling pathway operating at physiological sucrose concentrations controls metabolism via a feedback mechanism. In this paper bZIP11 target processes are identified using transiently increased nuclear bZIP11 levels and genome-wide expression analysis. bZIP11 affects the expression of hundreds of genes with proposed functions in biochemical pathways and signal transduction. The expression levels of approximately 80% of the genes tested are not affected by bZIP11 promoter-mediated overexpression of bZIP11. This suggests that <20% of the identified genes appear to be physiologically relevant targets of bZIP11. ASPARAGINE SYNTHETASE1 and PROLINE DEHYDROGENASE2 are among the rapidly activated bZIP11 targets, whose induction is independent of protein translation. Transient expression experiments in Arabidopsis protoplasts show that the bZIP11-dependent activation of the ASPARAGINE SYNTHETASE1 gene is dependent on a G-box element present in the promoter. Increased bZIP11 expression leads to decreased proline and increased phenylalanine levels. A model is proposed in which sugar signals control amino acid levels via the bZIP11 transcription factor.
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| 7. |
- He, Hanzi, et al.
(author)
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Effects of Parental Temperature and Nitrate on Seed Performance are Reflected by Partly Overlapping Genetic and Metabolic Pathways
- 2016
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In: Plant and Cell Physiology. - : Oxford University Press. - 0032-0781 .- 1471-9053. ; 57:3, s. 473-487
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Journal article (peer-reviewed)abstract
- Seed performance is affected by the seed maturation environment and previously, we have shown that temperature, nitrate and light intensity were the most influential environmental factors affecting seed performance. Seeds developed in these environments were selected to assess the underlying metabolic pathways, using a combination of transcriptomics and metabolomics. These analyses revealed that the effects of the temperature and nitrate parental environments were reflected by partly overlapping genetic and metabolic networks, as indicated by similar changes in metabolites and transcripts expression levels. Nitrogen-metabolism related metabolites (asparagine, GABA and allantoin) were significantly decreased in both low temperature (15°C) and low nitrate (N0) maturation environments. Correspondingly, nitrogen-metabolism genes (ALLANTOINASE, NITRATE REDUCTASE 1, NITRITE REDUCTASE 1 and NITRILASE 4) were differentially regulated in the low temperature and nitrate maturation environments, as compared with control conditions. High light intensity during seed maturation increased galactinol content, and displayed a high correlation with seed longevity. Low light had a genotype-specific effect on cell surface encoding genes in the DELAY OF GERMINATION 6-Near Isogenic Line (NILDOG6). Overall, the integration of phenotypes, metabolites and transcripts led to new insights in the regulation of seed performance.
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| 8. |
- Henriksson, Eva, et al.
(author)
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Homeodomain leucine zipper class I genes in Arabidopsis. Expression patterns and phylogenetic relationships
- 2005
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In: Plant Physiology. - : American Society of Plant Biologists. - 0032-0889 .- 1532-2548. ; 139:1, s. 509-518
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Journal article (pop. science, debate, etc.)abstract
- Members of the homeodomain leucine zipper (HDZip) family of transcription factors are present in a wide range of plants, from mosses to higher plants, but not in other eukaryotes. The HDZip genes act in developmental processes, including vascular tissue and trichome development, and several of them have been suggested to be involved in the mediation of external signals to regulate plant growth. The Arabidopsis ( Arabidopsis thaliana) genome contains 47 HDZip genes, which, based on sequence criteria, have been grouped into four different classes: HDZip I to IV. In this article, we present an overview of the class I HDZip genes in Arabidopsis. We describe their expression patterns, transcriptional regulation properties, duplication history, and phylogeny. The phylogeny of HDZip class I genes is supported by data on the duplication history of the genes, as well as the intron/exon patterning of the HDZip-encoding motifs. The HDZip class I genes were found to be widely expressed and partly to have overlapping expression patterns at the organ level. Further, abscisic acid or water deficit treatments and different light conditions affected the transcript levels of a majority of the HDZip I genes. Within the gene family, our data show examples of closely related HDZip genes with similarities in the function of the gene product, but a divergence in expression pattern. In addition, six HDZip class I proteins tested were found to be activators of gene expression. In conclusion, several HDZip I genes appear to regulate similar cellular processes, although in different organs or tissues and in response to different environmental signals.
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| 9. |
- Hoffmann, Gesa, et al.
(author)
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Arabidopsis RNA processing body components LSM1 and DCP5 aid in the evasion of translational repression during Cauliflower mosaic virus infection
- 2022
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In: The Plant Cell. - : Oxford University Press. - 1040-4651 .- 1532-298X. ; 34:8, s. 3128-3147
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Journal article (peer-reviewed)abstract
- Viral infections impose extraordinary RNA stress, triggering cellular RNA surveillance pathways such as RNA decapping, nonsense-mediated decay, and RNA silencing. Viruses need to maneuver among these pathways to establish infection and succeed in producing high amounts of viral proteins. Processing bodies (PBs) are integral to RNA triage in eukaryotic cells, with several distinct RNA quality control pathways converging for selective RNA regulation. In this study, we investigated the role of Arabidopsis thaliana PBs during Cauliflower mosaic virus (CaMV) infection. We found that several PB components are co-opted into viral factories that support virus multiplication. This pro-viral role was not associated with RNA decay pathways but instead, we established that PB components are helpers in viral RNA translation. While CaMV is normally resilient to RNA silencing, dysfunctions in PB components expose the virus to this pathway, which is similar to previous observations for transgenes. Transgenes, however, undergo RNA quality control-dependent RNA degradation and transcriptional silencing, whereas CaMV RNA remains stable but becomes translationally repressed through decreased ribosome association, revealing a unique dependence among PBs, RNA silencing, and translational repression. Together, our study shows that PB components are co-opted by the virus to maintain efficient translation, a mechanism not associated with canonical PB functions.
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| 10. |
- Hoffmann, Gesa, et al.
(author)
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Cauliflower mosaic virus protein P6 is a multivalent node for RNA granule proteins and interferes with stress granule responses during plant infection
- 2023
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In: The Plant Cell. - : Oxford University Press. - 1040-4651 .- 1532-298X. ; 35:9, s. 3363-3382
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Journal article (peer-reviewed)abstract
- Biomolecular condensation is a multipurpose cellular process that viruses use ubiquitously during their multiplication. Cauliflower mosaic virus replication complexes are condensates that differ from those of most viruses, as they are nonmembranous assemblies that consist of RNA and protein, mainly the viral protein P6. Although these viral factories (VFs) were described half a century ago, with many observations that followed since, functional details of the condensation process and the properties and relevance of VFs have remained enigmatic. Here, we studied these issues in Arabidopsis thaliana and Nicotiana benthamiana. We observed a large dynamic mobility range of host proteins within VFs, while the viral matrix protein P6 is immobile, as it represents the central node of these condensates. We identified the stress granule (SG) nucleating factors G3BP7 and UBP1 family members as components of VFs. Similarly, as SG components localize to VFs during infection, ectopic P6 localizes to SGs and reduces their assembly after stress. Intriguingly, it appears that soluble rather than condensed P6 suppresses SG formation and mediates other essential P6 functions, suggesting that the increased condensation over the infection time-course may accompany a progressive shift in selected P6 functions. Together, this study highlights VFs as dynamic condensates and P6 as a complex modulator of SG responses.
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