Reidunn Aalen

• Shi, Chunlin; von Wangenheim, Daniel; Herrmann, Ullrich; Wildhagen, Mari; Kulik, Ivan; Kopf, Andreas; Ishida, Takashi; Olsson, Vilde; Anker, Mari Kristine; Albert, Markus; Butenko, Melinka Alonso; Felix, Georg; Sawa, Shinichiro; Claassen, Manfred; Friml, Jiří & Aalen, Reidunn B. (2018). The dynamics of root cap sloughing in Arabidopsis is regulated by peptide signalling. Nature Plants.  ISSN 2055-026X.  4(8), s 596- 604 . doi: 10.1038/s41477-018-0212-z
• Czyzewicz, Nathan; Wildhagen, Mari; Cattaneo, Pietro; Stahl, Yvonne; Pinto, Karine Gustavo; Aalen, Reidunn B.; Butenko, Melinka Alonso; Simon, Rüdiger; Hardtke, Christian S. & De Smet, Ive (2015). Antagonistic peptide technology for functional dissection of CLE peptides revisited. Journal of Experimental Botany.  ISSN 0022-0957.  66(17), s 5367- 5374 . doi: 10.1093/jxb/erv284
• Stø, Ida Myhrer; Orr, Russell; Fooyontphanich, Kim; Jin, Xu; Knutsen, Jonfinn Mordekai Blix; Fischer, Urs; Tranbarger, Timothy J.; Nordal, Inger & Aalen, Reidunn B. (2015). Conservation of the abscission signaling peptide IDA during Angiosperm evolution: Withstanding genome duplications and gain and loss of the receptors HAE/HSL2. Frontiers in Plant Science.  ISSN 1664-462X.  6(OCTOBER) . doi: 10.3389/fpls.2015.00931
• Vie, Ane Kjersti; Najafi, Javad; Liu, Bin; Winge, Per; Butenko, Melinka Alonso; Hornslien, Karina Stensland; Kumpf, Robert; Aalen, Reidunn B.; Bones, Atle M. & Brembu, Tore (2015). The IDA/IDA-LIKE and PIP/PIP-LIKE gene families in Arabidopsis: Phylogenetic relationship, expression patterns, and transcriptional effect of the PIPL3 peptide. Journal of Experimental Botany.  ISSN 0022-0957.  66(17), s 5351- 5365 . doi: 10.1093/jxb/erv285 Full text in Research Archive. Show summary

  Peptide ligands play crucial roles in the life cycle of plants by modulating the innate immunity against pathogens and regulating growth and developmental processes. One well-studied example is INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which controls floral organ abscission and lateral root emergence in Arabidopsis thaliana. IDA belongs to a family of five additional IDA-LIKE (IDL) members that have all been suggested to be involved in regulation of Arabidopsis development. Here we present three novel members of the IDL subfamily and show that two of them are strongly and rapidly induced by different biotic and abiotic stresses. Furthermore, we provide data that the recently identified PAMP-INDUCED SECRETED PEPTIDE (PIP) and PIP-LIKE (PIPL) peptides, which show similarity to the IDL and C-TERMINALLY ENCODED PEPTIDE (CEP) peptides, are not only involved in innate immune response in Arabidopsis but are also induced by abiotic stress. Expression patterns of the IDA/IDL and PIP/PIPL genes were analysed using in silico data, qRT-PCR and GUS promoter lines. Transcriptomic responses to PIPL3 peptide treatment suggested a role in regulation of biotic stress responses and cell wall modification.

• Butenko, Melinka Alonso; Wildhagen, Mari; Albert, Markus; Jehle, Anna; Kalbacher, Hubert; Aalen, Reidunn B. & Felix, Georg (2014). Tools and strategies to match peptide-ligand receptor pairs. The Plant Cell.  ISSN 1040-4651.  26(5), s 1838- 1847 . doi: 10.1105/tpc.113.120071
• Kumpf, Robert; Thorstensen, Tage; Rahman, Mohummad Aminur; Heyman, Jefri; Nenseth, Hatice Zeynep; Lammens, Tim; Herrmann, Ullrich; Swarup, Ranjan; Veiseth, Silje Veie; Emberland, Gitiga; Bennett, Malcolm J.; De Veylder, Lieven & Aalen, Reidunn B. (2014). The ASH1-RELATED3 SET-domain protein controls cell division competence of the meristem and the quiescent center of the arabidopsis primary root. Plant Physiology.  ISSN 0032-0889.  166(2), s 632- 643 . doi: 10.1104/pp.114.244798
• Rahman, Mohummad Aminur; Kristiansen, Per Eugen; Veiseth, Silje Veie; Andersen, Jan Terje; Yap, Kyoko L.; Zhou, Ming-Ming; Sandlie, Inger; Thorstensen, Tage & Aalen, Reidunn B. (2014). The arabidopsis histone methyltransferase SUVR4 binds ubiquitin via a domain with a four-helix bundle structure. Biochemistry.  ISSN 1520-4995.  53(13), s 2091- 2100 . doi: 10.1021/bi401436h
• Aalen, Reidunn B.; Wildhagen, Mari; Stø, Ida Myhrer & Butenko, Melinka Alonso (2013). IDA: a peptide ligand regulating cell separation processes in Arabidopsis. Journal of Experimental Botany.  ISSN 0022-0957.  64(17), s 5253- 5261 . doi: 10.1093/jxb/ert338
• Kumpf, Robert; Shi, Chunlin; Larrieu, Antoine; Stø, Ida Myhrer; Butenko, Melinka Alonso; Péret, Benjamin; Riiser, Even; Bennett, Malcolm & Aalen, Reidunn B. (2013). Floral organ abscission peptide IDA and its HAE/HSL2 receptors control cell separation during lateral root emergence. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  110(13), s 5235- 5240 . doi: 10.1073/pnas.1210835110
• Liu, Bin; Butenko, Melinka Alonso; Shi, Chunlin; Bolivar, Jenny; Winge, Per; Stenvik, Grethe-Elisabeth; Vie, Ane Kjersti; Leslie, Michelle; Brembu, Tore; Kristiansen, Wenche; Bones, Atle M.; Patterson, Sara E.; Liljegren, Sarah & Aalen, Reidunn B. (2013). NEVERSHED and INFLORESCENCE DEFICIENT IN ABSCISSION are differentially required for cell expansion and cell separation during floral organ abscission in Arabidopsis thaliana. Journal of Experimental Botany.  ISSN 0022-0957.  64(17), s 5345- 5357 . doi: 10.1093/jxb/ert232
• Marshall, Alex; Aalen, Reidunn B.; Audenaert, Dominique; Beeckman, Tom; Broadley, Martin R.; Butenko, Melinka Alonso; Caño-Delgado, Ana I.; de Vries, Sacco; Dresselhaus, Thomas; Felix, Georg; Graham, Neil S.; Foulkes, John; Granier, Christine; Greb, Thomas; Grossniklaus, Ueli; Hammond, John P.; Heidstra, Renze; Hodgman, Charlie; Hothorn, Michael; Inzé, Dirk; Østergaard, Lars; Russinova, Eugenia; Simon, Rüdiger; Skirycz, Aleksandra; Stahl, Yvonne; Zipfel, Cyril & De Smete, Ive (2012). Tackling Drought Stress: RECEPTOR-LIKE KINASES Present New Approaches. The Plant Cell.  ISSN 1040-4651.  24(6), s 2262- 2278 . doi: 10.1105/tpc.112.096677
• Hoppmann, Verena; Thorstensen, Tage; Kristiansen, Per Eugen; Veiseth, Silje Veie; Rahman, Mohummad Aminur; Finne, Kenneth; Aalen, Reidunn B. & Aasland, Rein (2011). The CW domain, a new histone recognition module in chromatin proteins. EMBO Journal.  ISSN 0261-4189.  30(10), s 1939- 1952 . doi: 10.1038/emboj.2011.108
• Shi, Chunlin; Stenvik, Grethe-Elisabeth; Vie, Ane Kjersti; Bones, Atle M.; Pautot, V; Proveniers, M; Aalen, Reidunn B. & Butenko, Melinka Alonso (2011). Arabidopsis Class I KNOTTED-Like Homeobox Proteins Act Downstream in the IDA-HAE/HSL2 Floral Abscission Signaling Pathway. The Plant Cell.  ISSN 1040-4651.  23(7), s 2553- 2567 . doi: 10.1105/tpc.111.084608
• Shirzadi, Reza; Andersen, Ellen Dehnes; Bjerkan, Katrine; Gloeckle, Barbara M; Heese, Maren; Ungru, Alexander; Winge, Per; Koncz, C; Aalen, Reidunn B.; Schnittger, Arp & Grini, Paul Eivind (2011). Genome-Wide Transcript Profiling of Endosperm without Paternal Contribution Identifies Parent-of-Origin-Dependent Regulation of AGAMOUS-LIKE36. PLoS Genetics.  ISSN 1553-7390.  7(2) . doi: 10.1371/journal.pgen.1001303
• Thorstensen, Tage; Grini, Paul Eivind & Aalen, Reidunn B. (2011). SET domain proteins in plant development. Biochimica et Biophysica Acta. Gene Regulatory Mechanisms.  ISSN 1874-9399.  1809(8), s 407- 420 . doi: 10.1016/j.bbagrm.2011.05.008
• Veiseth, Silje Veie; Rahman, Mohummad Aminur; Yap, Kyoko L.; Fischer, Andreas; Jacobsen, Wolfgang Mathias; Reuter, Gunter; Zhou, Ming-Ming; Aalen, Reidunn B. & Thorstensen, Tage (2011). The SUVR4 Histone Lysine Methyltransferase Binds Ubiquitin and Converts H3K9me1 to H3K9me3 on Transposon Chromatin in Arabidopsis. PLoS Genetics.  ISSN 1553-7390.  7(3) . doi: 10.1371/journal.pgen.1001325
• Butenko, M; Vie, Ane Kjersti; Brembu, Tore; Aalen, RB & Bones, Atle M. (2009). Plant peptides in signalling: looking for new partners. Trends in Plant Science.  ISSN 1360-1385.  14(5), s 255- 263 . doi: 10.1016/j.tplants.2009.02.002
• Grini, Paul Eivind; Alm, Vibeke; Thorstensen, Tage; Vizcay-Barrena, Gema; Windju, Susanne; Tommy S., Jørstad; Wilson, Zoe E. & Aalen, Reidunn B. (2009). The ASH1 HOMOLOG 2 (ASHH2) Histone H3 Methyltransferase Is Required for Ovule and Anther Development in Arabidopsis. PLoS ONE.  ISSN 1932-6203.  4(11), s e7817- e7817
• Stangeland, B; Rosenhave, EM; Winge, Per; Berg, Anita; Berg, A; Amundsen, SS; Karabeg, M; Mandal, A; Bones, Atle M.; Grini, P & Aalen, RB (2009). AtMBD8 is involved in control of flowering time in the C24 ecotype of Arabidopsis thaliana. Physiologia Plantarum : An International Journal for Plant Biology.  ISSN 0031-9317.  136(1), s 110- 126 . doi: 10.1111/j.1399-3054.2009.01218.x
• Mckim, SM; Stenvik, Grethe-Elisabeth; Butenko, Melinka Alonso; Kristiansen, Wenche; Cho, SK; Hepworth, SR; Aalen, Reidunn B. & Haughn, GW (2008). The BLADE-ON-PETIOLE genes are essential for abscission zone formation in Arabidopsis. Development.  ISSN 0950-1991.  135 . doi: 10.1242/dev.012807
• Stenvik, Grethe-Elisabeth; Butenko, Melinka Alonso & Aalen, Reidunn B. (2008). Identification of a putative receptor-ligand pair controlling cell separation in plants. Article addendum. Plant Signalling & Behavior.  ISSN 1559-2316.  3, s 1109- 1110
• Stenvik, Grethe-Elisabeth; Tandstad, Nora Martinussen; Guo, Y; Shi, Chunlin; Kristiansen, Wenche; Holmgren, Asbjørn; Clark, SE; Aalen, Reidunn B. & Butenko, Melinka Alonso (2008). The EPIP peptide of INFLORESCENCE DEFICIENT IN ABSCISSION is sufficient to induce abscission in Arabidopsis through the receptor-like kinases HAESA and HAESA-LIKE2. The Plant Cell.  ISSN 1040-4651.  20, s 1805- 1817 . doi: 10.1105/tpc.108.059139
• Thorstensen, Tage; Grini, Paul E.; Mercy, Inderjit S.; Alm, Vibeke; Erdal, Sigrid; Aasland, Rein & Aalen, Reidunn B. (2008). The Arabidopsis SET-domain protein ASHR3 is involved in stamen development and interacts with the bHLH transcription factor ABORTED MICROSPORES (AMS). Plant Molecular Biology.  ISSN 0167-4412.  66(1), s 47- 59 . doi: 10.1007/s11103-007-9251-y
• Stabell, Marianne; Larsson, Jan; Aalen, Reidunn B. & Lambertsson, Andrew (2007). Drosophila dSet2 functions in H3-K36 methylation and is required for development. Biochemical and Biophysical Research Communications - BBRC.  ISSN 0006-291X.  359(3), s 784- 789 . doi: 10.1016/j.bbrc.2007.05.189 Show summary

  Abstract Lysine methylation has important functions in biological processes that range from heterochromatin formation to transcription regulation. Here, we demonstrate that Drosophila dSet2 encodes a developmentally essential histone H3 lysine 36 (K36) methyltransferase. Larvae subjected to RNA interference-mediated (RNAi) suppression of dSet2 lack dSet2 expression and H3-K36 methylation, indicating that dSet2 is the sole enzyme responsible for this modification in Drosophila melanogaster. dSet2 RNAi blocks puparium formation and adult development, and causes partial (blister) separation of the dorsal and ventral wing epithelia, defects suggesting a failure of the ecdysone-controlled genetic program. A transheterozygous EcR null mutation/dSet2 RNAi combination produces a complete (balloon) separation of the wing surfaces, revealing a genetic interaction between EcR and dSet2. Using immunoprecipitation, we demonstrate that dSet2 associates with the hyperphosphorylated form of RNA polymerase II (RNAPII).

• Stabell, Marianne; Bjørkmo, Mona; Aalen, Reidunn B. & Lambertsson, Andrew (2006). The Drosophila SET domain encoding gene dEset is essential for proper development. Hereditas.  ISSN 0018-0661. . doi: Online
• Aalen, Reidunn B.; Butenko, Melinka Alonso; Stenvik, Grethe-Elisabeth; Tandstad, Nora Martinussen & Patterson, Sara E. (2006). Genetic control of floral abscission, In Jaime A. Teixeira da Silva (ed.),  Floriculture, Ornamental and Plant Biotechnology: Advances and Topical Issues.  Global Science Books Ltd..  ISBN 978-4-903313-00-9.  Vol. 1, Part I, Chapter 12.  s 101 - 108
• Butenko, Melinka Alonso; Stenvik, Grethe-Elisabeth; Alm, Vibeke; Sæther, Barbro Elisabet; Patterson, Sara E. & Aalen, Reidunn B. (2006). Ethylene dependent and independent pathways controlling floral abscission are revealed to converge using promoter::reporter gene constructs in the ida abscission mutant. Journal of Experimental Botany.  ISSN 0022-0957.  57(14), s 3627- 3637 . doi: 10.1093/jxb/erl130 Show summary

  The process of floral organ abscission in Arabidopsis thaliana can be modulated by ethylene and involves numerous genes contributing to cell separation. One gene that is absolutely required for abscission is INFLORESCENCE DEFICIENT IN ABSCISSION, IDA, as the ida mutant is completely blocked in abscission. To elucidate the genetic pathways regulating floral abscission, molecular markers expressed in the floral abscission zone have been studied in an ida mutant background. Using plants with promoter–reporter gene constructs including promoters of a novel FLORAL ABSCISSION ASSOCIATED gene (FAA) encoding a putative single-stranded binding protein (BASIL), chitinase (CHIT::GUS) and cellulase (BAC::GUS), it is shown that IDA acts in the last steps of the abscission process. These markers, as well as HAESA, encoding a receptor-like kinase, were unaffected in their temporal expression patterns in ida compared with wild-type plants; thus showing that different regulatory pathways are active in the abscission process. In contrast to BASIL, CHIT::GUS and BAC::GUS showed, however, much weaker induction of expression in an ida background, consistent with a reduction in pathogen-associated responses and a lack of total dissolution of cell walls in the mutant. IDA, encoding a putative secreted peptide ligand, and HAESA appeared to have identical patterns of expression in floral abscission zones. Lastly, to address the role of ethylene, IDA::GUS expression in the wild type and the ethylene-insensitive mutant etr1-1 was compared. Similar temporal patterns, yet restricted spatial expression patterns were observed in etr1-1, suggesting that the pathways regulated by IDA and by ethylene act in parallel, but are, to some degree, interdependent.

• Skårn, Magne; Eike, Morten Christoph; Meza, Trine Johansen; Mercy, Inderjit Singh; Jakobsen, Kjetill Sigurd & Aalen, Reidunn B. (2006). An inverted repeat transgene with a structure that cannot generate double-stranded RNA, suffers silencing independent of DNA methylation. Transgenic research.  ISSN 0962-8819.  15, s 489- 500
• Stabell, Marianne; Eskeland, R; Bjørkmo, Mona; Larsson, J; Aalen, Reidunn; Imhof, A & Lambertsson, Gøran Andrew (2006). The Drosophila G9a gene encodes a multi-catalytic histone methyltransferase required for normal development. Nucleic Acids Research.  ISSN 0305-1048.  34, s 4609- 4621
• Stenvik, Grethe-Elisabeth; Butenko, Melinka Alonso; Urbanowicz, BR; Rose, JKC & Aalen, Reidunn B. (2006). overexpression of inflorescence deficient in abscission activates cell separation in vestigial abscission zones in Arabidopsis. The Plant Cell.  ISSN 1040-4651.  18, s 1467- 1476
• Thorstensen, Tage; Fischer, Andreas; Sandvik, Silje; Johnsen, Sylvia; Grini, Paul Eivind; Reuter, Gunter & Aalen, Reidunn B. (2006). The Arabidopsis SUVR4 protein is a nucleolar histone methyltransferase with preference for monomethylated H3K9. Nucleic Acids Research.  ISSN 0305-1048.  34(19), s 5461- 5470 . doi: 10.1093/nar/gkl687
• Eike, Morten Christoph; Mercy, Inderjit Singh & Aalen, Reidunn B. (2005). Transgene silencing may be mediated by aberrant sense promoter sequence transcripts generated from cryptic promoters. Cellular and Molecular Life Sciences (CMLS).  ISSN 1420-682X.  62 . doi: 10.1007/s00018-005-5301-2
• Stangeland, Biljana; Nestestog, Ragnhild; Grini, Paul Eivind; Skrbo-Larssen, Nirma; Berg, Anita; Salehian, Zhian; Mandal, Abul & Aalen, Reidunn B. (2005). Molecular analysis of Arabidopsis endosperm and embryo promoter trap lines: reporter-gene expression can result from T-DNA insertions in antisense orientation, in introns and in intergenic regions, in addition to sense insertion at the 5' end of genes. Journal of Experimental Botany.  ISSN 0022-0957.  56(419), s 2495- 2505 . doi: 10.1093/jxb/eri242
• Stangeland, Biljana; Nestestog, Ragnhild; Grini, Paul; Skrbo, Nirma; Berg, Anita; Salehian, Zhian; Mandal, Abul & Aalen, Reidunn (2005). Molecular analysis of Arabidopsis endosperm and embryo promoter trap lines: reporter-gene expression can result from T-DNA insertions in antisense orientation, in introns and in intergenic regions, in addition to sense insertion at the 5' end of genes. Journal of Experimental Botany.  ISSN 0022-0957.  419(Sep;56), s 2495- 505 Show summary

  Random insertions of promoterless reporter genes in genomes are a common tool for identifying marker lines with tissue-specific expression patterns. Such lines are assumed to reflect the activity of endogenous promoters and should facilitate the cloning of genes expressed in the corresponding tissues. To identify genes active in seed organs, plant DNA flanking T-DNA insertions (T-DNAs) have been cloned in 16 Arabidopsis thaliana GUS-reporter lines. T-DNAs were found in proximal promoter regions, 5' UTR or intron with GUS in the same (sense) orientation as the tagged gene, but contrary to expectations also in inverted orientation in the 5' end of genes or in intergenic regions. RT-PCR, northern analysis, and data on expression patterns of tagged genes, compared with the expression pattern of the reporter lines, suggest that the expression pattern of a reporter gene will reflect the pattern of a tagged gene when inserted in sense orientation in the 5' UTR or intron. When inserted in the promoter region, the reporter-gene expression patterns may be restricted compared with the endogenous gene. Among the trapped genes, the previously described nitrate transporter gene AtNRT1.1, the cyclophilin gene ROC3, and the histone deacetylase gene AtHD2C were found. Reporter-gene expression when positioned in antisense orientation, for example, in the SLEEPY1 gene, is indicative of antisense expression of the tagged gene. For T-DNAs found in intergenic regions, it is suggested that the reporter gene is transcribed from cryptic promoters or promoters of as yet unannotated genes.

• Berg, Anita; Meza, Trine Johansen; Mahic, Mirela; Thorstensen, Tage; Kristiansen, Kjetil & Aalen, Reidunn (2003). Ten members of the Arabidopsis gene family encoding methyl-CpG-binding domain proteins are transcriptionally active and at least one, AtMBD11, is crucial for normal development. Nucleic Acids Research.  ISSN 0305-1048.  31(18), s 5291- 5304
• Butenko, Melinka Alonso; Patterson, Sara E.; Grini, Paul Eivind; Stenvik, Grethe-Elisabeth; Amundsen, Svanstrøm Silja; Mandal, Abul & Aalen, Reidunn (2003). INFLORESCENCE DEFICIENT IN ABSCISSION Controls Floral Organ Abscission in Arabidopsis and Identifies a Novel Family of Putative Ligands in Plants. The Plant Cell.  ISSN 1040-4651.  15, s 2296- 2307
• Haslekås, Camilla; Grini, Paul Eivind; Nordgard, Silje H.; Thorstensen, Tage; Viken, Marte K.; Nygaard, Vigdis & Aalen, Reidunn (2003). ABI3 mediates expression of the peroxiredoxin antioxidant AtPER1 gene and induction by oxidative stress. Plant Molecular Biology.  ISSN 0167-4412.  53, s 313- 326
• Haslekås, Camilla; Viken, Marte K.; Grini, Paul Eivind; Nygaard, Vigdis; Nordgard, Silje H.; Meza, Trine Johansen & Aalen, Reidunn (2003). Seed 1-Cys peroxiredoxin antioxidants are not involved in dormancy, but contribute to inhibition of germination during stress. Plant Physiology.  ISSN 0032-0889.  133, s 1148- 1157
• Stangeland, Biljana; Salehian, Zhian; Aalen, Reidunn; Mandal, Abul & Olsen, Odd-Arne (2003). Isolation of GUS marker lines for genes expressed in Arabidopsis endosperm, embryo and maternal tissues. Journal of Experimental Botany.  ISSN 0022-0957.  54(381), s 279- 290
• Stangeland, Biljana; Salehian, Zhian; Aalen, Reidunn; Mandal, Abul & Olsen, Odd-Arne (2003). Isoaltion of GUS marker lines for genes expressed in Arabidopsis endosperm, embryo and maternal tissues. Journal of Experimental Botany.  ISSN 0022-0957.  54, s 279- 290 Show summary

  In order to identify marker lines expressing GUS in various endosperm compartments and at different developmental stages, a collection of Arabidopsis thaliana (L.) Heynh. promoter trap lines were screened. The screen identified 16 lines displaying GUS-reporter gene expression in the endosperm, embryo and other seed organs. The distinctive patterns of GUS expression in these lines provide molecular markers for most cell compartments in the endosperm of Arabidopsis seeds at all developmental stages, and represent a valuable research tool for characterizing present and future Arabidopsis seed mutants. GUS expression patterns of these 16 lines are presented here. One line showed chalazal endosperm-specific GUS activity at the heart stage of embryo development. In six lines embryo-specific GUS activity was detected. Six lines exhibited GUS activity predominantly in the endosperm and embryo while two lines showed strong GUS activity in all seed organs. In one line GUS activity was detected in integuments and syncytial endosperm, while the GUS activity at the cotyledonary stage of the embryo was seed coat-specific. In addition, two funiculus markers and two silique markers expressed in the abscission zone and the guard cells are also presented.

• Meza, Trine Johansen; Enerly, Espen; Børud, Bente; Larsen, Frank; Mandal, Abul; Aalen, Reidunn & Jakobsen, Kjetill Sigurd (2002). A human CpG island randomly inserted into a plant genome is protected from methylation. Transgenic research.  ISSN 0962-8819.  11, s 133- 142
• Meza, Trine Johansen; Enerly, Espen; Børud, Bente; Larsen, Frank; Mandal, Abul; Aalen, Reidunn & Jakobsen, Kjetill Sigurd (2002). A human CpG island randomly inserted into a plant genome is protected from methylation. Plant Molecular Biology Reporter.  ISSN 0735-9640.  11, s 133- 142 Show summary

  In vertebrate genomes the dinucleotide CpG is heavily methylated, except in CpG islands, which are normally unmethylated. It is not clear why the CpG islands are such poor substrates for DNA methyltransferase. Plant genomes display methylation, but otherwise the genomes of plants and animals represent two very divergent evolutionary lines. To gain a further understanding of the resistance of CpG islands to methylation, we introduced a human CpG island from the proteasome-like subunit I gene into the genome of the plant Arabidopsis thaliana. Our results show that prevention of methylation is an intrinsic property of CpG islands, recognized even if a human CpG island is transferred to a plant genome. Two different parts of the human CpG island - the promoter region/ first exon and exon2-4 - both displayed resistance against methylation, but the promoter/ exon1 construct seemed to be most resistant. In contrast, certain sites in a plant CpG-rich region used as a control transgene were always methylated. The frequency of silencing of the adjacent nptII (KmR) gene in the human CpG constructs was lower than observed for the plant CpG-rich region. These results have implications for understanding DNA methylation, and for construction of vectors that will reduce transgene silencing.

• Meza, Trine Johansen; Stangeland, Biljana; Mercy, Inderjit Singh; Skårn, Magne; Nymoen, Dag A.; Berg, Anita; Butenko, Melinka Alonso; Håkelien, Anne-Mari; Haslekås, Camilla; Meza-Zepeda, Leonardo A. & Aalen, Reidunn (2002). Analyses of single-copy Arabidopsis T-DNA transformed lines show that the presence of vector backbone sequences, short inverted repeats and DNA methylation is not sufficient or necessary for the induction of transgene silencing. Nucleic Acids Research.  ISSN 0305-1048.  30(20), s 4556- 4566 Show summary

  In genetically transformed plants, transgene silencing has been correlated to multiple and complex insertions of foreign DNA, e.g. T-DNA and vector backbone sequences. Occasionally, single-copy transgenes also suffer transgene silencing. We have compared integration patterns and T-DNA/plant DNA junctions in a collection of 37 single-copy T-DNA transformed Arabidopsis lines, of which 13 displays silencing. Vector sequences were found integrated in five lines, but only one of these displays silencing. Truncated T-DNA copies, positioned in inverse orientation to an intact T-DNA copy, were discovered in three lines. The whole nptII gene with pnos promoter was present in the truncated copy of one such line in which heavy silencing has been observed. In the two other lines no silencing has been observed over five generations. Thus, vector sequences and short additional T-DNA sequences are not sufficient or necessary to induce transgene silencing. DNA methylation of selected restriction endonuclease sites could not be correlated to silencing. Our collection of T-DNA/plants DNA junctions has also been used to evaluate current models of T-DNA integration. Data for some of our lines are compatible with T-DNA integration in double-stranded breaks, while for others initial invasion of plant DNA by the left or by the right T-DNA end seem important.

• Meza, Trine; Stangeland, Biljana; Singh Mercy, Inderjit; Skarn, Magne; Nymoen, Dag Andre; Berg, Anita; Butenko, Melinka; Håkelien, Anne-Mari; Haslekås, Camilla; Meza-Zepeda, Leonardo A & Aalen, Reidunn (2002). Analyses of single-copy Arabidopsis T-DNA-transformed lines show that the presence of vector backbone sequences, short inverted repeats and DNA methylation is not sufficient or necessary for the induction of transgene silencing. ?.  30, s 4556- 4566 Show summary

  In genetically transformed plants, transgene silencing has been correlated with multiple and complex insertions of foreign DNA, e.g. T-DNA and vector backbone sequences. Occasionally, single-copy transgenes also suffer transgene silencing. We have compared integration patterns and T-DNA/plant DNA junctions in a collection of 37 single-copy T-DNA-transformed Arabidopsis lines, of which 13 displayed silencing. Vector sequences were found integrated in five lines, but only one of these displayed silencing. Truncated T-DNA copies, positioned in inverse orientation to an intact T-DNA copy, were discovered in three lines. The whole nptII gene with pnos promoter was present in the truncated copy of one such line in which heavy silencing has been observed. In the two other lines no silencing has been observed over five generations. Thus, vector sequences and short additional T-DNA sequences are not sufficient or necessary to induce transgene silencing. DNA methylation of selected restriction endonuclease sites could not be correlated with silencing. Our collection of T-DNA/plant DNA junctions has also been used to evaluate current models of T-DNA integration. Data for some of our lines are compatible with T-DNA integration in double-strand breaks, while for others initial invasion of plant DNA by the left or by the right T-DNA end seem important.

• Aalen, Reidunn; Salehian, Zhian & Steinum, Terje M. (2001). Stability of barley aleurone transcripts: Dependence on protein synthesis, influence of the starchy endosperm and destabilization by GA3. Physiologia Plantarum : An International Journal for Plant Biology.  ISSN 0031-9317.  112, s 403- 413 . doi: 10.1034/j.1399-3054.2001.1120314.x Show summary

  We have studied the stability of Barley aleurone and embryo expressed (Balem) transcripts in aleurone layers. The Per1, Ole1, and Ole2 transcripts are abundant during desiccation and in dry resting seeds, while B12D and B22E transcripts are expressed mainly during seed maturation and germination. From 21 to 40 days post anthesis (DPA) incubation of aleurone layers resulted in a substantial, but differential reduction in the levels of these transcripts. In contrast, Balem transcript levels in aleurone layers of incubated embryoless grains were (except for B22E) similar to those of freshly dissected layers. Cycloheximide lowered transcript levels significantly. This indicates that a protein-synthesis dependent, mRNA-stabilizing mechanism is active in the aleurone cells when attached to the starchy endosperm. At the onset of seed desiccation (40 DPA), half-lives of transcripts to be stored in the dry seed were up to several days longer than the half-life of B22E, which decreases during seed maturation. While the Per1, Ole1, and Ole2 transcript levels decline rapidly in the aleurone layers of mature, germinating seeds, the genes are actively transcribed, and their transcripts highly stable in the aleurone of incubated embryoless seeds. The expression of Ole1 and Ole2, as well as Per1, can be repressed 100- to 1000-fold by GA3 in a dose dependent manner. Abscisic acid can counteract the GA3-repression. Incubations with transcriptional and translational inhibitors indicate that GA3 inhibits the transcription of these genes and at the same time induces a protein-synthesis dependent mechanism destabilizing their mRNA molecules present.

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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..
• 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.
• Aalen, Reidunn B. (2013). Maturing peptides open for communication. Journal of Experimental Botany.  ISSN 0022-0957.  64(17), s 5231- 5235 . doi: 10.1093/jxb/ert378
• Vie, Ane Kjersti; Najafi, Javad; Liu, Bin; Winge, Per; Butenko, Melinka Alonso; Hornslien, K; Kumpf, Robert; Aalen, Reidunn B.; Bones, Atle M. & Brembu, Tore (2012). Expression of the extended IDA gene family in Arabidopsis thaliana: evidence for post-transcriptional regulation by mRNA decapping.
• 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.
• Aalen, Reidunn B. (2009). Cell-separation processes in Arabidopsis involve peptide ligands and leucine-rich-repeat receptor-like kinases. Show summary

  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.

• 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. Show summary

  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.

• Aalen, Reidunn B.; Grini, Paul Eivind; Thorstensen, Tage; Alm, Vibeke; Vizcay-Barrena, Gema; Windju, Susanne S. & Wilson, Zoe E. (2009). The ASH1 HOMOLOG 2 (ASHH2) histone H3 methyltransferase is required for ovule and anther development in Arabidopsis. Show summary

  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.

• Aalen, Reidunn B.; Grini, Paul Eivind; Thorstensen, Tage; Alm, Vibeke; Vizcay-Barrena, Gema; Windju, Susanne S. & Wilson, Zoe E. (2009). The ASH1 HOMOLOG 2 (ASHH2) histone H3 methyltransferase is required for ovule and anther development in Arabidopsis. Show summary

  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.

• 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. Show summary

  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.

• Aalen, Reidunn B.; Stenvik, Grethe-Elisabeth; Shi, Chunlin & Butenko, Melinka Alonso (2009). HAE and HSL receptors in cell separation events.
• 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. Show summary

  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.

• 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. Show summary

  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.

• 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.
• 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
• Aalen, Reidunn B. (2008). IDA/IDL peptides and HEASA/HAESA-LIKE kinases - putative ligand-receptor pairs controlling cell-separation processes in Arabidopsis.
• Aalen, Reidunn B. (2007). The 'conspiracy' between chromatin modification and transcription factors.
• 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.
• 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.
• 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.
• 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.
• Aalen, Reidunn B. (2004). Epigenetikk hos planter. Naturen.  ISSN 0028-0887.  128(4), s 228- 235
• Alm, Vibeke & Aalen, Reidunn B. (2004). Identification of new gene families and their function using bioinformatics tools and reverse genetics.
• 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.
• 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. Show summary

  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.

• Flobakk, Morten; Løset, Geir Åge; Rosenhave, Ellen Maryann; Sandlie, Inger; Aalen, Reidunn B.; Blomhoff, Heidi Kiil & Havnes, Jarle (2004). PBL på grunnkurset i cellebiologi og genetikk på Institutt for molekylær Biovitenskap. NBS-nytt.  ISSN 0801-3535.  (4), s 20- 26
• Helgesen, Carsten; Tufteland, Katharina; Puntervoll, Pål; Wibrand, Karin; Aalen, Reidunn & Aasland, Rein (2004). CHRAB - a knowledge base for chromatin associated proteins and protein domains.
• Lee, YeonKyeong; Derbyshire, Paul; Wilson, Reginald H.; Aalen, Reidunn & Hvoslef-Eide, Anne Kathrine (2004). Cell wall alteration in abscission. Show summary

  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

• Aalen, Reidunn (2003). Arabidopsis research at the University of Oslo.
• Aalen, Reidunn (2003). Sinnets verktøykasse � uten Umbraco-nøkkel? Anmeldelse av Iver Mysteruds bok �Mennesket og moderne evolusjonsteori�. Forskerforum.  ISSN 0800-1715.  (10)
• Aalen, Reidunn (2003). The biology of GM plants: in the present and in the future.
• Alm, Vibeke & Aalen, Reidunn B. (2003). Functional analyses of six members of the SET domain proteins in Arabidopsis thaliana. Show summary

  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.

• 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.
• Butenko, Melinka Alonso; Patterson, Sara E.; Grini, Paul Eivind; Stenvik, Grethe-Elisabeth; Amundsen, Svanstrøm Silja; Mandal, Abul & Aalen, Reidunn (2003). IDA controls floral organ abscission in Arabidopsis, and identifies a novel family of putative ligands in plants.
• Butenko, Melinka Alonso; Patterson, Sara E.; Stenvik, Grethe-Elisabeth; Grini, Paul Eivind; Thorstensen, Tage; Mandal, Abul & Aalen, Reidunn (2003). The IDA gene, controlling floral organ abscission in Arabidopsis, identifies a novel family of putative ligands in plants.
• 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.
• Eike, Morten C.; Mercy, Inderjit Singh & Aalen, Reidunn (2003). Mechanisms of transgene silencing in Arabidopsis thaliana.
• Grini, Paul Eivind; Skrbo, Nirma; Stangeland, Biljana & Aalen, Reidunn (2003). Genetic and molecular analysis of gametophytic maternal effect mutants in Arabidopsis.
• 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.
• Haslekås, Camilla; Viken, Marte K.; Nordgard, Silje H.; Grini, Paul Eivind; Thorstensen, Tage; Nygaard, Vigdis; Meza, Trine Johansen & Aalen, Reidunn (2003). Study of thte potential function and regulation of the peroxiredoxin AtPER1.
• 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.
• Rosenhave, Ellen Maryann; Berg, Anita; Meza, Trine Johansen; Mahic, Mirela; Thorstensen, Tage; Kristiansen, Kjetil & Aalen, Reidunn (2003). Arabidopsis thaliania Methyl-CpG-binding (MBD) proteins � the missing link?.
• Skrbo, Nirma; Grini, Paul Eivind & Aalen, Reidunn (2003). Towards molecular cloning of the capulet2 gametophyte maternal-effect mutant in Arabidopsis thaliana.
• 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.
• Stabell, Marianne; Aalen, Reidunn & Lambertsson, Andrew (2003). Molecular cloning and characterization of three putative SET domain containing genes in Drosophila.
• Sæther, Barbro Elisabet & Aalen, Reidunn (2003). NARC � Norwegian Arabidopsis Research Centre � University of Oslo.
• 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.
• Thorstensen, Tage; Grini, Paul Eivind; Mercy, Inderjit Singh & Aalen, Reidunn (2003). A SET-domain encoding gene possibly involved in embryo development in Arabidopsis thaliana.
• 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.
• Stangeland, Biljana; Salehian, Zhian; Aalen, Reidunn; Mandal, Abul & Olsen, Odd-Arne (2001). Promoter trapping of seven genes expressed in Arabidopsis endosperm.
• Stangeland, Biljana; Salehian, Zhian; Aalen, Reidunn; Mandal, Abul & Olsen, Odd-Arne (2001). Promoter trapping of three genes expressed in Arabidopsis siliques.
• Stangeland, Biljana; Salehian, Zhian; Mandal, Abul; Aalen, Reidunn; Ferstad, Hilde-Gunn Opsahl & Olsen, Odd-Arne (2001). Promoter trapping of two unknown genes involved in arabidopsis endosperm development.
• Aalen, Reidunn (2001). Identification and characterization of SET-domain genes in Arabidopsis.
• Aalen, Reidunn (2001). Oxidative stress tolerance mechanisms. Show summary

  When dry, mature seeds take up water (phase I of germination) respiration is resumed (phase II) and reactive oxygen species (ROS) are produced as metabolic by-products. The phases I and II are similar for both in dormant and non-dormant seeds, but dormant seeds do not enter the third phase of germination, i.e. radicle elongation and a second burst of respiration. Most antioxidants are first induced to high levels during phase III. However, protection against ROS is clearly needed during imbibition to prevent crucial damage to membranes, DNA and proteins. The peroxiredoxin genes Per1 in barley and AtPer1 in Arabidopsis are likely to function as protectors against ROS during imbibition. Peroxiredoxins are thiol-requiring antioxidants found in organisms ranging from bacteria to humans. Per1 and AtPer1 belong to a subgroup with one conserved cysteine residue (1-Cys), and their in vitro antioxidant function has been demonstrated. They are seed specific, and expressed only in the parts of the seed surviving desiccation - the embryo and the aleurone layers (Stacy et al., 1996; Haslekås et al., 1998). The PER1 protein is present in the nucleus of embryo and aleurone cells, indicating a role in protection of DNA (Stacy et al., 1999, Aalen 2000). The transcripts are expressed in a dormancy-related manner, and disappear rapidly during germination. In barley aleurone layers Per1 is down-regulated by GA3 in a dose-dependent manner that can be counteracted by ABA (Aalen et al., 2001). Experiments with translational and transcriptional inhibitors indicate that GA3 inhibits transcription and also induces mRNA-destabilization. Both the Per1 and the AtPer1 promoters contain a putative Antioxidant Response Element and an Abscisic Acid Response Element. Our most recent results demonstrate that the AtPer1 gene can be induced by oxidative stress in the presence of the transcription factor ABI3.

• Baumbusch, Lars Oliver; Assalkhou, Reza; Thorstensen, Tage & Aalen, Reidunn (2001). Identification of functional SET-domain genes in Arabidopsis thaliana. Show summary

  SET-domain proteins are multifunctional chromatin regulators with a highly conserved sequence motif. Their role in epigenetic control of gene expression has been discovered in Drosophila, where three classes of SET-domain proteins exist: Supressor of variegation 3-9, Su(var)3-9; Enhancer of zeste, E(z)} and trithorax, (trx). In Arabidopsis only a few genes with SET-domain have been studied: CURLY LEAF (CLF) regulates expression of floral homeotic genes and MEDEA (MEA), (similar to FERTILIZATION INDEPENDENT SEED DEVELOPMENT 1, FIS1) which is involved in the repression of endosperm development in the absence of fertilisation. Both genes are most similar to E(z). The aim of this project is to determine further SET-domain genes in Arabidopsis through comparative and functional genomics. We have identified several new potential SET-domain genes and located their genomic positions. Our results indicate, that the SET-domain sequences in Arabidopsis have a tendency to cluster in at least 4 regions. We have confirmed, that two of the potenional genes are active. Parts of the hypothesised genes were sequenced and their RNA expression studied. For further investigations we will utilise the reverse genetic approach, like double-stranded RNA interference (RNAi). In addition, we have planned functional complementation studies in Drosophila mutants.

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