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Herrmann, Ullrich; WILDHAGEN, Mari; Stø, Ida Myhrer; Butenko, Melinka Alonso & Aalen, Reidunn B.
(2014).
Secreted IDA-LIKE peptide ligands and their receptors regulate crucial aspects of root development – root cap sloughing, gravitropism and meristem length.
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Herrmann, Ullrich; WILDHAGEN, Mari; Butenko, Melinka Alonso & Aalen, Reidunn B.
(2014).
Small peptides are involved in cell separation processes in the root.
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Vie, Ane Kjersti; Najafi, Javad; Liu, Bin; Winge, Per; Butenko, Melinka Alonso & Hornslien, K
[Vis alle 10 forfattere av denne artikkelen]
(2012).
Expression of the extended IDA gene family in Arabidopsis thaliana: evidence for post-transcriptional regulation by mRNA decapping.
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Butenko, Melinka Alonso; Shi, Chunlin & Aalen, Reidunn B.
(2010).
Class I KNOX proteins involved in floral abscission downstream in the IDA-HAE/HSL2 signaling pathway.
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Aalen, Reidunn B.; Grini, Paul Eivind; Thorstensen, Tage; Alm, Vibeke; Vizcay-Barrena, Gema & Windju, Susanne S.
[Vis alle 7 forfattere av denne artikkelen]
(2009).
The ASH1 HOMOLOG 2 (ASHH2) histone H3 methyltransferase is required for ovule and anther development in Arabidopsis.
Vis sammendrag
SET-domain proteins add methyl groups to lysine (K) residues of histone tails, which may function as marks activating or repressing transcription. The ASH1 HOMOLOG 2 (ASHH2) protein of Arabidopsis thaliana groups with Drosophila ASH1, a positive maintainer of gene expression, and yeast Set2, a histone H3K36 methyltransferase, and has been implicated as a histone H3K4 or H3K36 methyltransferase. ashh2 mutants display pleiotropic developmental defects, including early flowering. Here we focus on the role of ASHH2 in plant reproduction, of homeotic changes in floral organ identity and specific effects on the development of the reproductive organs. On the female side, close to 80% of the mature ovules lack embryo sac. On the male side, anthers frequently develop without pollen sacs and where present show specific defects in the tapetum layer. As a result, the number of functional pollen per anther was reduced by up to ~90%. Transcriptional profiling identified more than 600 down-regulated genes in ashh2 mutant inflorescences, including genes involved in determination of floral organ identity, embryo sac development and anther/pollen development. Currently, there is a discrepancy in the literature on the primary substrate of ASHH2 methylation. We observed a reduction of H3K36 trimethylation (me3) but not H3K4me3 or H3K36me2 in chromatin from selected down-regulated genes. Thus, our analysis strongly suggests that ASHH2 works via H3K36 trimethylation in the regulation of genes essential in reproductive development.
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Aalen, Reidunn B.; Stenvik, Grethe-Elisabeth; Shi, Chunlin & Butenko, Melinka Alonso
(2009).
Identification of putative peptide ligands and receptors involved in control of cell-separation processes in plants.
Vis sammendrag
The novel ligand/receptor pair, IDA and the closely related receptor-like kinases (RLKs) HAESA (HAE) and HAESA-LIKE 2 (HSL2), controls floral organ abscission in Arabidopsis. The IDA gene encodes a protein of 77 amino acids (aa), with a N-terminal signal sequence exporting the protein. Genes encoding IDA-LIKE proteins, that share a common C-terminal 12aa motif (PIP), are present both in Arabidopsis and other plant species. The active IDA peptide resided within an extended PIP motif (EPIP). IDA-LIKE (IDL) proteins can in part substitute for IDA function. The IDL expression patterns indicate involvement in regulation of various cell separation events, e.g. root cap sloughing and seed dispersal. Plants constitutively overexpressing IDA exhibit earlier abscission of floral organs and ectopic abscission of flowers, branches and cauline leaves and overexpression of the IDL proteins mimic this phenotype. The over-expression phenotype is dependent on functional HAE and HSL2 RLKs. We suggest that the IDL peptides interact with HEASA-LIKE receptors to control cell-separation processes, and that new peptide-ligand/receptor pairs may be identified by a hypothesis-driven approach with the aid of genetics and new methods to identify active peptides and direct peptide-RLK interactions.
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Aalen, Reidunn B.; Grini, Paul Eivind; Thorstensen, Tage & Alm, Vibeke
(2009).
The ASHH2 histone 3 lysine methyltransferase is required for ovule and anther development in Arabidopsis thaliana.
Vis sammendrag
SET-domain proteins are methyltransferases that add methyl groups to lysine (K) residues of histone tails, which function as marks activating or repressing transcription. SET-domain proteins can be divided into evolutionarily conserved classes in animals and plants. Mutation of the ASH1 HOMOLOG 2 (ASHH2) gene of the model plant Arabidopsis has severe pleiotropic effects on growth, development and fertility, in that it results in homoetic changes of floral organ identity, affects male and female gametogenesis, and especially the development of the reproductive organs. On the female side, close to 80 percent of the mature ovules lack embryo sac. On the male side, anthers in part develop without pollen sacs (locules) and in developed locules the tapetum layer, which provides material to the pollen wall, is distorted. Together this results in a more that 75 percent reduction in mature functional pollen grains. Transcriptional profiling was used to identify changes in gene expression in ashh2 mutant inflorescences. Genes involved in determination of floral organ identity, embryo sac development and anther/pollen development were found down-regulated. On such genes ChIP detected reduction of H3K36me3 but not H3K4me3 or H3K36me2. Our study indicates that ASHH2 is a major global H3K36 trimethyltransferase in Arabidopsis.
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Aalen, Reidunn B.; Stenvik, Grethe-Elisabeth; Butenko, Melinka Alonso & Shi, Chunlin
(2009).
Identification of putative peptide ligands and receptors involved in control of cell-separation processes in plants.
Vis sammendrag
Recently a novel ligand/receptor pair, IDA and the closely related receptor-like kinases (RLKs) HAESA (HAE) and HAESA-LIKE 2 (HSL2), was revealed to control floral organ abscission in Arabidopsis (Stenvik et al., 2008, Plant Cell, 20: 1805-1817). The IDA gene encodes a protein of only 77 amino acids (aa), with a N-terminal signal sequence that exports the protein out of the cell. There is evidence suggesting that the protein is processed to release a small peptide from the C-terminal end. Genes encoding IDA-LIKE proteins have been identified both in Arabidopsis and other plant species. They are all less than 100 aa, with a N-terminal signal peptide and a common C-terminal motif called PIP (Butenko et al., 2003, Plant Cell, 15: 2296-2307). The active IDA peptide resided within an extended PIP motif (EPIP) of 20 aa (Stenvik et al., 2008). In Arabidopsis IDA-LIKE (IDL) proteins can in part substitute for IDA function. Promoter:GUS expression studies of the IDL genes indicate that these genes may be involved in regulating various cell separation events such as root cap sloughing, stomata development and formation of hydathodes. A 35S:IDA line constitutively overexpressing IDA exhibit earlier abscission of floral organs and ectopic abscission at the bases of the pedicel, branches of the inflorescence, and cauline leaves (Stenvik et al. 2006, Plant Cell 18: 1467-1476) and overexpression of the IDL proteins mimic this phenotype (Stenvik et al., 2008). The over-expression phenotype is dependent on functional HAE and HSL2 RLKs. We suggest that the IDL peptides interact with HEASA-LIKE receptors to control cell-separation processes. Interestingly, The IDA/IDL-HAE/HSL2 signalling system shows similarities to that of CLV3/CLE-CLV1/CLV2 involved in meristem maintenance. We propose that new peptide-ligand/receptor pairs may be identified by a hypothesis-driven approach, and the aid of genetics, as well as new methods to identify active peptides and direct peptide-RLK interactions.
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Aalen, Reidunn B.; Stenvik, Grethe-Elisabeth; Shi, Chunlin & Butenko, Melinka Alonso
(2009).
HAE and HSL receptors in cell separation events.
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Aalen, Reidunn B.
(2009).
Cell-separation processes in Arabidopsis involve peptide ligands and leucine-rich-repeat receptor-like kinases.
Vis sammendrag
Cell separation events take place throughout the life cycle of plants, and facilitate organ loss, root cap sloughing, dehiscence, fruit and seed shedding. After pollination has taken place in Arabidopsis, floral organs abscise. INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) that encodes a protein of 77 amino acids (aa) including an N-terminal export signal, is absolutely required for this process. Genetic evidence suggests that IDA is a small peptide ligand interacting with the receptor-like kinases (RLKs) HEASA and HEASA-LIKE2. Thus this is one of the few plant ligand/receptor pairs identified to date [3]. Genes encoding IDA-LIKE proteins, that share a common C-terminal 12aa motif (PIP), are present both in Arabidopsis and other plant species. The active IDA peptide resided within an extended PIP motif (EPIP). IDA-LIKE (IDL) proteins can in part substitute for IDA function, however, the IDL expression patterns indicate involvement in regulation of various other cell separation events, e.g. root cap sloughing and seed dispersal. Plants constitutively overexpressing IDA exhibit earlier abscission of floral organs and ectopic abscission of flowers, branches and cauline leaves and overexpression of the IDL proteins mimic this phenotype. The over-expression phenotype is dependent on functional HAE and HSL2 RLKs. We suggest that the IDL peptides interact with HEASA-LIKE receptors to control cell-separation processes, and that new peptide-ligand/receptor pairs may be identified by a hypothesis-driven approach with the aid of genetics and new methods to identify active peptides and direct peptide-RLK interactions.
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Aalen, Reidunn B.; Stenvik, Grethe-Elisabeth; Shi, Chunlin & Butenko, Melinka Alonso
(2009).
Peptide ligands and receptors involved in control of cell-separation processes in Arabidopsis.
Vis sammendrag
Cell separation events take place throughout the life cycle of plants, and facilitate organ loss, root cap sloughing, dehiscence, fruit and seed shedding. After pollination has taken place in Arabidopsis, floral organs abscise. INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) that encodes a protein of 77 amino acids (aa) including an N-terminal export signal, is absolutely required for this process. Genetic evidence suggests that IDA is a small peptide ligand interacting with the receptor-like kinases (RLKs) HEASA and HEASA-LIKE2. Thus this is one of the few plant ligand/receptor pairs identified to date [3]. Genes encoding IDA-LIKE proteins, that share a common C-terminal 12aa motif (PIP), are present both in Arabidopsis and other plant species. The active IDA peptide resided within an extended PIP motif (EPIP). IDA-LIKE (IDL) proteins can in part substitute for IDA function, however, the IDL expression patterns indicate involvement in regulation of various other cell separation events, e.g. root cap sloughing and seed dispersal. Plants constitutively overexpressing IDA exhibit earlier abscission of floral organs and ectopic abscission of flowers, branches and cauline leaves and overexpression of the IDL proteins mimic this phenotype. The over-expression phenotype is dependent on functional HAE and HSL2 RLKs. We suggest that the IDL peptides interact with HEASA-LIKE receptors to control cell-separation processes, and that new peptide-ligand/receptor pairs may be identified by a hypothesis-driven approach with the aid of genetics and new methods to identify active peptides and direct peptide-RLK interactions.
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Aalen, Reidunn B.; Grini, Paul Eivind; Thorstensen, Tage; Alm, Vibeke; Vizcay-Barrena, Gema & Windju, Susanne S.
[Vis alle 7 forfattere av denne artikkelen]
(2009).
The ASH1 HOMOLOG 2 (ASHH2) histone H3 methyltransferase is required for ovule and anther development in Arabidopsis.
Vis sammendrag
The more than 30 SET-domain proteins of Arabidopsis can be classified in evolutionarily conserved subgroups that methylate different lysine residues on histone tails (1).The ASH1 HOMOLOG 2 (ASHH2) protein is similar to the Drosophila transcriptional activator ASH1, and the histone H3K36 methyltransferase Set2 from yeast. ashh2 mutants display pleiotropic developmental defects, including early flowering (2,3). We have focused on the role of ASHH2 in plant reproduction, of homeotic changes in floral organ identity and specific effects on the development of the reproductive organs. On the female side, close to 80% of the mature ovules lack embryo sac. On the male side, anthers frequently develop without pollen sacs and where present show specific defects in the tapetum layer, reducing the number of functional pollen per anther by up to ~90%. Transcriptional profiling identified more than 600 down-regulated genes in ashh2 mutant inflorescences, including genes involved in determination of floral organ identity, embryo sac development and anther/pollen development. We observed a reduction of H3K36 trimethylation (me3) but not H3K4me3 or H3K36me2 in chromatin of such genes. Thus, our analysis strongly suggests that ASHH2 works via H3K36 trimethylation in the regulation of genes essential in reproductive development.
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Aalen, Reidunn B.
(2008).
BOOK REVIEW: Plant Cell Separation and Adhesion, Annual Plant Reviews, J.A. Roberts, Z. Gonzalez-Carranza (Eds.). Blackwell Publishing, Oxford, UK (2007).
Journal of plant physiology.
ISSN 0176-1617.
165,
s. 469–470.
doi:
10.1016/j.jplph.2007.12.004.
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Aalen, Reidunn B.
(2008).
IDA/IDL peptides and HEASA/HAESA-LIKE kinases - putative ligand-receptor pairs controlling cell-separation processes in Arabidopsis.
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Aalen, Reidunn B.
(2007).
The 'conspiracy' between chromatin modification and transcription factors.
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Aalen, Reidunn B.; Thorstensen, Tage; Alm, Vibeke & Grini, Paul Eivind
(2007).
Chromatin modification in Arabidopsis: SET-domain proteins with localization in euchromatin or the nucleolus and identification of a novel histone methyltransferase specificity.
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Stenvik, Grethe-Elisabeth; Tandstad, Nora Martinussen; Butenko, Melinka Alonso & Aalen, Reidunn B.
(2007).
INFLORESCENCE DEFICIENT IN ABSCISSION (IDA)AND IDA-LIKE (IDL) PEPTIDES AND THEIR ROLES IN CELL SEPARATION PROCESSES.
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Stenvik, Grethe-Elisabeth; Tandstad, Nora Martinussen; Holmgren, Asbjørn; Kristiansen, Wenche; Butenko, Melinka Alonso & Aalen, Reidunn B.
(2007).
INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) AND IDA-LIKE (IDL) PEPTIDES AND THEIR ROLES IN PLANT DEVELOPMENT.
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Lee, YeonKyeong; Derbyshire, Paul; Wilson, Reginald H.; Aalen, Reidunn & Hvoslef-Eide, Anne Kathrine
(2004).
Cell wall alteration in abscission.
Vis sammendrag
Abscission is the process of natural separation of organs from plant. This is well-programmed process during development of the plants or in response to environmental stress. Plant parts such as pollen, fruits, seeds, and leaflets may be shed in response to developmental cues for efficient dispersal or propagation of the plant. Unwanted organs such floral organ may be shed when they no longer serve a functional role to the plants. Damaged or infected organs may be rapidly shed as a mechanism of defence. Abscission can result in loss of quality in agricultural and horticultural crops. The abscission process can be assumed to be based on inter- and intracellular signalling events that remain to be identified in detail. The goals of the recent NFR-project is to identify the cell wall modifications taking place during abscission and factors involved in this process in the model plant Arabidopsis and the economically important plant poinsettia (Christmas star), which is also used as a model plant in another NFR project. To identify which genes and enzymes are involved in abscission, the Arabidopsis thaliana floral abscission mutant inflorescence deficient in abscission (ida) mutant would be used as a valuable tool alongside with poinsettia.We have established a way of inducing abscission in poinsettia; by decapitating the buds abscission will take place in 7-10 days, depending on season and growing conditions. It is difficult to analyse the abscission zone (AZ) biochemically, because theseparation zone is only a few cell layers thick. Fourier Transform Infrared Microspectroscopy (FT-IR) has been established as a powerful tool for analysis of plant cell walls (Carpita & McCann, 2002; McCann et al., 2001). It is an extremely rapid, non-destructive spectroscopic method that can quantitatively detect a range of functional groups. FT-IR is therefore a useful method to identify a broad range of the alteration in this limited area of the cell and reveal biochemical information to elucidatethe function of these hydrolytic enzymes and cell wall modification during abscission. The preliminary studies using FT-IR in poinsettia shows that pectins decrease and lignins/lignans increase in the abscission zone at day seven, just before the buds abscise. References: Carpita NC & McCann MC, 2002. The functions of cell wall polysaccharides in composition and architecture revealed through mutations. Plant & Soil 247 (1): 71-80 McCann, MC, Bush, M, Milioni, M, Sado, P, Stacey, NJ, Catchpole, G, Defernez, M, Carpita, NC, Hofte, H, Ulvskov, P, Wilson, RH & Roberts, K, 2001. Approaches to understanding the functional architecture of the plant cell wall. Phytochemistry, 57(6): 811-821
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Helgesen, Carsten; Tufteland, Katharina; Puntervoll, Pål; Wibrand, Karin; Aalen, Reidunn & Aasland, Rein
(2004).
CHRAB - a knowledge base for chromatin associated proteins and protein domains.
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Aalen, Reidunn B.
(2004).
Epigenetikk hos planter.
Naturen.
ISSN 0028-0887.
128(4),
s. 228–235.
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Flobakk, Morten; Løset, Geir Åge; Rosenhave, Ellen Maryann; Sandlie, Inger; Aalen, Reidunn B. & Blomhoff, Heidi Kiil
[Vis alle 7 forfattere av denne artikkelen]
(2004).
PBL på grunnkurset i cellebiologi og genetikk på Institutt for molekylær Biovitenskap.
NBS-nytt.
ISSN 0801-3535.
s. 20–26.
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Alm, Vibeke & Aalen, Reidunn B.
(2004).
Identification of new gene families and their function using bioinformatics tools and reverse genetics.
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Thorstensen, Tage; Grini, Paul Eivind; Alm, Vibeke; Butenko, Melinka Alonso; Rosenhave, E. Maryann & Aalen, Reidunn
(2004).
Identification of new gene families and their function using bioinformatics tools and reverse genetics.
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Aalen, Reidunn
(2003).
Sinnets verktøykasse � uten Umbraco-nøkkel? Anmeldelse av Iver Mysteruds bok �Mennesket og moderne evolusjonsteori�.
Forskerforum.
ISSN 0800-1715.
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Sæther, Barbro Elisabet & Aalen, Reidunn
(2003).
NARC � Norwegian Arabidopsis Research Centre � University of Oslo.
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Butenko, Melinka Alonso; Patterson, Sara E.; Grini, Paul Eivind; Stenvik, Grethe-Elisabeth; Amundsen, Svanstrøm Silja & Mandal, Abul
[Vis alle 7 forfattere av denne artikkelen]
(2003).
IDA controls floral organ abscission in Arabidopsis, and identifies a novel family of putative ligands in plants.
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Aalen, Reidunn
(2003).
Arabidopsis research at the University of Oslo.
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Thorstensen, Tage; Grini, Paul Eivind; Mercy, Inderjit Singh & Aalen, Reidunn
(2003).
A SET-domain encoding gene possibly involved in embryo development in Arabidopsis thaliana.
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Grini, Paul Eivind; Skrbo, Nirma; Stangeland, Biljana & Aalen, Reidunn
(2003).
Genetic and molecular analysis of gametophytic maternal effect mutants in Arabidopsis.
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Aalen, Reidunn
(2003).
The biology of GM plants: in the present and in the future.
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Butenko, Melinka Alonso; Patterson, Sara E.; Stenvik, Grethe-Elisabeth; Grini, Paul Eivind; Thorstensen, Tage & Mandal, Abul
[Vis alle 7 forfattere av denne artikkelen]
(2003).
The IDA gene, controlling floral organ abscission in Arabidopsis, identifies a novel family of putative ligands in plants.
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Haslekås, Camilla; Viken, Marte K.; Nordgard, Silje H.; Grini, Paul Eivind; Thorstensen, Tage & Nygaard, Vigdis
[Vis alle 8 forfattere av denne artikkelen]
(2003).
Study of thte potential function and regulation of the peroxiredoxin AtPER1.
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Grini, Paul Eivind; Skrbo, Nirma; Stangeland, Biljana; Hülskamp, Martin; Jürgens, Gerd & Aalen, Reidunn
(2003).
Genetic and molecular analysis of gametophytic maternal effect mutants in Arabidopsis.
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Berg, Anita; Meza, Trine Johansen; Mahic, Mirela; Kristiansen, Kjetil & Aalen, Reidunn
(2003).
RNA interference with expression of Arabidopsis genes encoding putative methyl-CpG-binding proteins induces pleiotropic effects on plant development.
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Alm, Vibeke & Aalen, Reidunn B.
(2003).
Functional analyses of six members of the SET domain proteins in Arabidopsis thaliana.
Vis sammendrag
Higher-order chromatin structure has roles in the epigenetic control of development-dependent gene expression (Pirrotta, Trends Genet, 1997, 13: 314-318). Several proteins have been identified which play an important role in the maintenance of active or inactive states of chromatin in a cell-heritable manner. Some of these proteins enhance or suppress position effect variegation (PEV), which is heterochromatin-induced gene silencing (Reuter and Spierer, BioEssays, 1992, 14: 605?612). These enhancers and suppressors, and other chromatin modulating proteins, are involved in multimeric protein?protein interactions and share distinctive amino acid motifs like chromo domain, CXC domain, PHD finger or SET domain (Tschiersch et al., EMBO J, 1994, 13: 3822?383; Pirrota, 1998, Cell, 93: 333?336; Van Lohuizen et al, Mol Cell Biol, 1998, 18: 3572?3579). SET domains are 130?160 amino acid long and were named after three proteins in which they were originally identified in Drosophila; supressor of variegation (SU(VAR)3?9), enhancer of zeste (E(Z)) and trithorax (TRX). SU(VAR)3?9 is a suppressor of PEV, E(Z) belongs to the polycomb group (PcG) proteins, whereas TRX is a member of trithorax group (TrG) proteins. PcG proteins are involved in stable repression of homeotic genes, whereas TrG proteins are needed for the stable expression of homeotic genes, in appropriate segments, throughout the development of Drosophila. The presence of SET domain in these proteins suggests that they are important in the formation of expressable active or repressable silent chromatin states (Jenuwein et al., Cell Mol Life Sci, 1998, 54: 80?93).
The epigenetic control of gene expression is equally important in plants (Li et al. 2002, Goodrich and Tweedie 2002). By bioinformatics approach, (Baumbusch, Thorstensen et al., Nucleic Acids Research, 2001, 29: 4319-4333) have identified at least 27 SET domain-containing genes in Arabidopsis. Based on sequences of SET domains and cysteine-rich regions and other associated domains, these genes have also been classified into four distinct groups; E(Z), SU(VAR)3-9, TRX and ASH. E(Z) proteins are part of plant PcG complexes and show developmental roles during the plant life cycle, more specifically in control of plant reproduction and the vegetative?flowering transition (Hsieh T-F et al, Trends Plant Sci, 2003, 8: 439-445). So does the SU(VAR)3-9 protein KRYPTONITE/SUVH4 which represses transcription of flower homeotic and flowering time genes via its methyl transferase activity and subsequent reduction in histone H3 lysine 9 methylation (Jackson et al., Nature, 2002, vol. 416, 556-560; Malagnac et al, EMBO J, 2002, 16: 6842-52). Both the plant TRX and ASH proteins are homologs of TrG proteins, and similar to their function in the animal system, the Arabidopsis ATX1 has shown to function as an activator of homeotic genes (Alvarez-Venegas et al. Current Biology).
Six members of the SET domain proteins in Arabidopsis thaliana belonging to the SU(VAR)3-9, TRX and ASH proteins are under study to reveal their function. SALK T-DNA lines are genotypically and phenotypically screened, and expression studies are performed.
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Stabell, Marianne; Aalen, Reidunn & Lambertsson, Andrew
(2003).
Molecular cloning and characterization of three putative SET domain containing genes in Drosophila.
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Skrbo, Nirma; Grini, Paul Eivind & Aalen, Reidunn
(2003).
Towards molecular cloning of the capulet2 gametophyte maternal-effect mutant in Arabidopsis thaliana.
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Rosenhave, Ellen Maryann; Berg, Anita; Meza, Trine Johansen; Mahic, Mirela; Thorstensen, Tage & Kristiansen, Kjetil
[Vis alle 7 forfattere av denne artikkelen]
(2003).
Arabidopsis thaliania Methyl-CpG-binding (MBD) proteins � the missing link?
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Eike, Morten C.; Mercy, Inderjit Singh & Aalen, Reidunn
(2003).
Aberrant promoter transcripts and heavy methylation are inversely related in two Arabidopsis thaliana transgenic lines displaying variegated silencing of an nptII gene.
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Thorstensen, Tage; Alm, Vibeke; Johnsen, Sylvia & Aalen, Reidunn
(2003).
Chromatin modulating role for the members of the SU(VAR)3-9 subgroup of SET domain proteins in Arabidopsis thaliana.
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Thorstensen, Tage; Johnsen, Sylvia & Aalen, Reidunn
(2003).
Chromatin modulating role for the members of the SU(VAR)3-9 subgroup of SET domain proteins in Arabidopsis thaliana.
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Mahic, Mirela; Berg, Anita; Meza, Trine Johansen & Aalen, Reidunn
(2003).
A study of function and expression of three genes encoding putative methyl-CpG-binding proteins in Arabidopsis thaliana.
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Skrbo, Nirma; Grini, Paul Eivind; Jürgens, Gerd; Hülskamp, Martin & Aalen, Reidunn
(2003).
Towards molecular cloning of the capulet2 gametophytic maternal-efect mutant in Arabidopsis thaliana.
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Eike, Morten C.; Mercy, Inderjit Singh & Aalen, Reidunn
(2003).
Mechanisms of transgene silencing in Arabidopsis thaliana.
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Stangeland, Biljana; Salehian, Zhian; Nestestog, Ragnhild; Mandal, Abul; Aalen, Reidunn & Olsen, Odd-Arne
(2001).
Endosperm development in Arabidopsis.
Vis sammendrag
Kortmelding publisert i NBS-nytt 2001
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Stangeland, Biljana; Salehian, Zhian; Mandal, Abul; Aalen, Reidunn & Olsen, Odd-Arne
(2001).
Promoter trapping of three genes expressed in arabidopsis siliques.
Vis sammendrag
In a screen of Arabidopsis promoter trap lines (Vector pMHA2- promoterless gusA at the right T-DNA border; Abul Mandal, University of Skövde, Sweden) for endosperm genes (poster by B. Stangeland et al.), we detected three lines displaying GUS staining in 1) stomata, 2) embryo and hydatodes and 3) seed coat. Among the first 309 lines examined, 50 lines (16%) showed GUS expression in siliques. Of these, 22 lines (44%) displayed GUS expression only in seeds, 9 lines (18%) in silique tissue only and 4 lines (8%) exclusively in the siliques abscission zone. Twelve lines (24%) showed GUS staining both in siliques and seeds and 3 lines (6%) exhibited GUS activity in both seeds and in the abscission zone. Based on Southern blot analysis, approximately 50% of the lines posses single T-DNA copy insertions. Stomata -One of the transgenic lines shows GUS activity in guard cells on siliques and stem but not (or very weakly) on leaves. GUS staining is visible also in roots and auxillary meristems. Using Long Range Inverse PCR we isolated T-DNA flanking regions from this line. Sequence data revealed the integration of a promoterless GUS expression cassette in a gene with an unknown function. Hydatodes (leaves) and embryos -We also analyzed a line with the GUS activity in the hydatodes and embryos. Sequence analysis of the isolated plant flanking region revealed integration in the gene coding for a nitrate chlorate transporter protein with an unknown expression pattern. Seed coat -Two of our lines showed GUS activity only in the seed coat. We sequenced isolated plant promoter sequences from one of these lines and confirmed integration in a gene with an unknown function. We are currently working on several lines showing GUS activity in embryos andtransport system of the seed (maternal tissue, funiculus and embryo suspensor).
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Riiser, Even Sannes; Aalen, Reidunn B. & Butenko, Melinka Alonso
(2009).
Ligand-receptor matchmaking: The IDA-HAE/HSL2 signaling system and the IDL and HSL relatives.
Universitetet i Oslo.
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Butenko, Melinka Alonso & Aalen, Reidunn B.
(2006).
A genetic and molecular study of floral organ abscission in Arabidopsis thaliana using the mutant inflorescence deficient in abscission.
Unipub forlag.
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Eike, Morten Christoph; Mercy, Inderjit Singh & Aalen, Reidunn B.
(2004).
Characterising transgene silencing in single-copy Arabidopsis thaliana lines: DNA methylation in view of genomic and transcriptional context.
Universitetet i Oslo.
Vis sammendrag
A total of nine single-copy transgenic Arabidopsis thaliana lines displaying varying degrees of silencing of a nos promoter-nptII marker gene (encoding kanamycin-resistance) have been studied, with emphasis on two of these, line P4 and P10. Both of these lines show a very high frequency of nptII-silencing in one subline, but little or no silencing in other sublines, indicating epigenetic mechanisms.
One candidate is DNA methylation, which has been associated both with silencing on a transcriptional level (TGS) and with post-transcriptional gene silencing (PTGS). Using the bisulphite-mediated genomic DNA sequencing method, the methylation status of all cytosine positions in a sequence consisting of the nos promoter and the 5’-end of the nptII gene were investigated for both lines. The results show a very high degree of methylation for the silenced sublines, also in asymmetric cytosines, and a significantly lower degree of methylation in the sublines with little or no silencing. When comparing the promoter and transcribed regions, a preference for methylation of the former is observed, indicating that the nptII gene is subject to TGS.
Many models of silencing have evoked the presence of aberrant transcripts. Using RT-PCR, sense transcripts covering the promoter were detected for both of the investigated lines. Counter to what was expected, however, these RNAs were detected in sublines showing little or no silencing, whereas none or very low levels were detected in silenced plants. Promoter analyses and characterisation of the sequences flanking the nptII construct indicate that these transcripts may originate in cryptic promoter elements or as an extension of a recently reported endogenous transcript.
Based on these results and recent models of RNA-directed DNA methylation, a scenario is presented where the detected promoter transcripts are targeted and processed in the silenced sublines by components involved in silencing, resulting in sequence-specific methylation of the corresponding DNA.
