55 research outputs found

    The ring between ring fingers (RBR) protein family

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    An overview of the large and functionally diverse RBR protein family that mediates protein-protein interactions of various kinds in development and disease

    Transcriptional repression by MYB3R proteins regulates plant organ growth

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    In multicellular organisms, temporal and spatial regulation of cell proliferation is central for generating organs with defined sizes and morphologies. For establishing and maintaining the post-mitotic quiescent state during cell differentiation, it is important to repress genes with mitotic functions. We found that three of the Arabidopsis MYB3R transcription factors synergistically maintain G2/M-specific genes repressed in post-mitotic cells and restrict the time window of mitotic gene expression in proliferating cells. The combined mutants of the three repressor-type MYB3R genes displayed long roots, enlarged leaves, embryos, and seeds. Genome-wide chromatin immunoprecipitation revealed that MYB3R3 binds to the promoters of G2/M-specific genes and to E2F target genes. MYB3R3 associates with the repressor-type E2F, E2FC, and the RETINOBLASTOMA RELATED proteins. In contrast, the activator MYB3R4 was in complex with E2FB in proliferating cells. With mass spectrometry and pairwise interaction assays, we identified some of the other conserved components of the multiprotein complexes, known as DREAM/dREAM in human and flies. In plants, these repressor complexes are important for periodic expression during cell cycle and to establish a post-mitotic quiescent state determining organ size

    The importance and direction of current and future plant-UV research : break-out session discussions at the UV4Plants Network Meeting in Bled (April 15th -18th , 2018)

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    During the 2nd Network Meeting of UV4Plants at Bled (14th–18th April, 2018) the delegates engaged in a group discussion of prescient questions concerning the future of in plant-UV research. The discussion group was tasked to identify the most valuable directions for plant UV research to take, and to create a coherent framework for how to move the field forward. Here, the outcome of these discussions is summarised in sections that follow the composition of discussion groups as ideas taken from a molecular, biochemical and physiological perspective followed by those from an ecological and plant production perspective. In each case, first basic research questions are considered and then applications and methodological considerations are put forward. Finally, some common ground bringing the two perspectives together is discussed, with the aim of solving scaling problems and ways in which the UV4Plants network might be put to good use.Peer reviewe

    Induction of ARI12

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    Identification and Characterization of the ARIADNE Gene Family in Arabidopsis. A Group of Putative E3 Ligases

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    ARIADNE (ARI) proteins were recently identified in fruitfly (Drosophila melanogaster), mouse, and man because of their specific interaction with the ubiquitin-conjugating (E2) enzymes UbcD10, UbcM4, UbcH7, and UbcH8. They are characterized by specific motifs and protein structures that they share with PARKIN, and there is increasing evidence that ARI/PARKIN proteins function as E2-dependent ubiquitin-protein ligases. On the basis of homology and motif searches, 16 AtARI genes were identified in Arabidopsis. Analysis of the position of exons/introns and their chromosomal localization indicates that the AtARI gene family expanded via larger and smaller genome duplications. We present evidence that retroposition of processed mRNA may have also contributed to enlarging this gene family. Phylogenetic analyses divides the AtARI proteins into three subgroups. Two groups are absent in yeast, invertebrates, and vertebrates and may therefore represent new plant-specific subfamilies. Examination of the predicted protein sequences revealed that the ARI proteins share an additional leucine-rich region at the N terminus that is highly conserved in all phyla analyzed. Furthermore, conserved consensus signals for casein kinase II-dependent phosphorylation and for nuclear localization were identified. The in silico-based analyses were complemented with experimental data to quantify expression levels. Using real-time polymerase chain reaction, we show that the ARI genes are differentially transcribed. AtARI1 is highly expressed in all organs, whereas no transcripts could be detected for AtARI11, AtARI13, and AtARI14. AtARI12 and AtARI16 are expressed in an organ-specific manner in the roots and siliques, respectively

    Role of CrRLK1L Cell Wall Sensors HERCULES1 and 2, THESEUS1, and FERONIA in Growth Adaptation Triggered by Heavy Metals and Trace Elements

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    Cell walls are not only a protective barrier surrounding protoplasts but serve as signaling platform between the extracellular environment and the intracellular physiology. Ions of heavy metals and trace elements, summarized to metal ions, bind to cell wall components, trigger their modification and provoke growth responses. To examine if metal ions trigger cell wall sensing receptor like kinases (RLKs) of the Catharanthus roseus RLK1-like (CrRLK1L) family we employed a molecular genetic approach. Quantitative transcription analyses show that HERCULES1 (HERK1), THESEUS1 (THE1), and FERONIA (FER) were differently regulated by cadmium (Cd), nickel (Ni), and lead (Pb). Growth responses were quantified for roots and etiolated hypocotyls of related mutants and overexpressors on Cd, copper (Cu), Ni, Pb, and zinc (Zn) and revealed a complex pattern of gene specific, overlapping and antagonistic responses. Root growth was often inversely affected to hypocotyl elongation. For example, both HERK genes seem to negatively regulate hypocotyl elongation upon Cd, Ni, Zn, and Pb while they support root growth on Cd, Cu, and Ni. The different THE1 alleles exhibited a similar effect between roots and hypocotyls on Ni, where the loss-of-function mutant was more tolerant while the gain of function mutants were hypersensitive indicating that THE1 is mediating Ni specific inhibition of hypocotyl elongation in the dark. In contrast hypocotyl elongation of the knock-out mutant, fer-4, was hypersensitive to Ni but exhibited a higher tolerance to Cd, Cu, Pb, and Zn. These data indicate an antagonistic action between THE1 and FER in relation to hypocotyl elongation upon excess of Ni. FERs function as receptor for rapid alkalinization factors (RALFs) was tested with the indicator bromocresol purple. While fer-4 roots strongly acidified control and metal ion containing media, the etiolated hypocotyls alkalized the media which is consistent with the already shorter hypocotyl of fer-4. No other CrRLK1L mutant exhibited this phenotype except of the THE1:GFP overexpressor on Ni suggesting that THE1 might be involved in Ni induced and hypocotyl specific RALF signaling and growth regulating pathway. Overall, our findings establish a molecular link between metal ion stress, growth and the cell wall integrity sensors of the CrRLK1L family
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