Chromatin, DNA Methylation, RNAi and Epigenetic Regulation

  • Shawn Kaeppler

Transcriptional and post-transcriptional control of maize gene expression is proving to be important in many aspects of maize biology. The dramatic growth of research in this area has yielded exciting new discoveries which have enhanced our understanding of gene regulation in maize, and have linked previously diverse phenomena to central underlying mechanisms. In this review, I provide a summary of genes considered to function in chromatin-based transcriptional control of gene expression, in post-transcriptional gene silencing, and which link RNA molecules to heritable states of expression. Information from maize, or most relevant to maize, is cataloged according to gene families and groups. The topic area is too broad to provide a thorough synthesis for any gene family or pathway, but the review should allow the reader an entry point to access most maize information on this topic.


Histone Acetylation Histone Methylation Chromatin State Transcriptional Gene Silence Histone Chaperone 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alleman, M., and Doctor, J. (2000) Genomic imprinting in plants: observations and evolutionary implications. Plant Mol. Biol. 43,147–161.PubMedCrossRefGoogle Scholar
  2. Alleman, M., Sidorenko, L., McGinnis, K., Seshadri, V., Dorweiler, J.E., White, J., Sikkink, K., and Chandler, V.L. (2006) An RNA-dependent RNA polymerase is required for paramutation in maize. Nature 442,295–298.PubMedCrossRefGoogle Scholar
  3. Amedeo, P., Habu, Y., Afsar, K., Mittelsten Scheid, O., and Paszkowski, J. (2000) Disruption of the plant gene MOM releases transcriptional silencing of methylated genes. Nature 405,203–206.PubMedCrossRefGoogle Scholar
  4. Banks, J.A., Masson, P., and Federoff, N. (1988) Molecular mechanisms in the developmental regulation of the Suppressor-mutator maize transposable element system. Genes Devel. 2,1364–1380.PubMedCrossRefGoogle Scholar
  5. Bhat, R.A., Borst, J.W., Riehl, M., and Thompson, R.D. (2004) Interaction of maize Opaque-2 and the transcriptional co-activators GCN5 and ADA2, in the modulation of transcriptional activity. Plant Molec. Biol. 55,239–252.CrossRefGoogle Scholar
  6. Bhat, R.A., Riehl, M., Santandrea, G., Velasco, R., Slocombe, S., Donn, G., Steinbiss, H-H., Thompson, R.D., and Becker, H-A. (2003) Alteration of GCN5 levels in maize reveals dynamic responses to manipulating histone acetylation. Plant J. 33,455–469.PubMedCrossRefGoogle Scholar
  7. Brosch, G., Lusser, A., Goralik-Schramel, M., and Loidl, P. (1996) Purification and characterization of a high molecular weight histone deacetylase complex (HD2) of maize embryos. Biochem. 35,15907–15914.CrossRefGoogle Scholar
  8. Cao, X., Springer, N.M., Muszynski, M.G., Phillips, R.L., Kaeppler, S.M., and Jacobsen, S.E. (2000) Conserved plant genes with similarity to mammalian de novo DNA methyltransferases. Proc. Nat'l. Acad. Sci. USA 97,4979–4984.CrossRefGoogle Scholar
  9. Casati, P., Stapleton, A.E., Blum, J.E., Walbot, V. (2006) Genome wide analysis of high-altitude maize and gene knock-down stocks implicates chromatin remodeling proteins in response to UV-B. Plant J. 46,613–627.PubMedCrossRefGoogle Scholar
  10. Chuck, G., Cigan, A.M., Saeteum, K., and Hake, S. (2007) The heterochronic maize mutant Corngrass1 results from overexpression of a tandem microRNA. Nature Genet. 39,544–549.PubMedCrossRefGoogle Scholar
  11. Chadhuri, S., and Messing, J. (1994) Allele-specific imprinting of dzr1, a post-transcriptional regulator of zein accumulation. Proc. Nat'l. Acad. Sci. USA. 91,4867–4871.CrossRefGoogle Scholar
  12. Chuck, G., Cigan, A.M., Saeteurn, K., and Hake, S. (2007) The heterochronic maize mutant Corngrass1 results from overexpression of a tandem repeat microRNA. Nature Genet. 39,544–549.PubMedCrossRefGoogle Scholar
  13. Cigan, A.M., Unger-Wallace, E., and Haug-Collet, K. (2005) Transcriptional gene silencing as a tool for uncovering gene function in maize. Plant J. 43,929–940.PubMedCrossRefGoogle Scholar
  14. Cocciolone, S.M., and Cone, K.C. (1993) Pl-Bh, an anthocyanin regulatory gene of maize that leads to variegated pigmentation. Genetics 135,575–588.PubMedGoogle Scholar
  15. Danilevskaya, O.N., Hermon, P., Hantke, S., Muszynski, M.G., Kollipara, K., Ananiev, E.V. (2003) Duplicated fie genes in maize: expression pattern and imprinting suggest distinct functions. Plant Cell 15,425–438.PubMedCrossRefGoogle Scholar
  16. Das, P. and Messing, J. (1994) Variegated phenotype and developmental methylation changes of a maize allele originating from epimutation. Genetics 136,1121–1141.PubMedGoogle Scholar
  17. Dorweiler, J.E., Carey, C.C., Kubo, K.M., Hollick, J.B., Kermicle, J.L., and Chandler, V.L. (2000) mediator of paramutation1 is required for establishment and maintenance of paramutation at multiple loci. Plant Cell 12,2101–2118.PubMedCrossRefGoogle Scholar
  18. Earley, K.W., Shook, M.S., Brower-Toland, B., Hicks, L., Pikaard, C. (2007) In vitro specificities of Arabidopsis co-activator histone acetyltransferases: implications for histone hyperacetylation in gene activation. Plant J. 52:615–626.PubMedCrossRefGoogle Scholar
  19. Emberton, J., J. Ma, Y. Yuan and J.L. Bennetzen (2005) Gene enrichment in maize with hypomethylated partial restriction (HMPR) libraries. Genome Res. 15:1441–1446.PubMedCrossRefGoogle Scholar
  20. Fuchs, J., Demidov, D., Houben, A., and Schubert, I. (2006) Chromosomal histone modification patterns — from conservation to diversity. Trends Plant Sci. 11,199–208.PubMedCrossRefGoogle Scholar
  21. Grasser, K.D. (2003) Chromatin-associated HMGA and HMGB proteins: versatile co-regulators of DNA-dependent processes. Plant Molec. Biol. 53,281–295.CrossRefGoogle Scholar
  22. Grasser, K.D., Launholt, D., and Grasser, M. (2007) High mobility group proteins of the plant HMGB family: dynamic modulators of chromatin. Biochim. Biophys. Acta 1769,346–357.PubMedGoogle Scholar
  23. Gutierrez-Marcos, J.F., Costa, L.M., Pra, M.D., Scholten, S., Kranz, E., Perez, P., and Dickinson, H.G. (2007) Epigenetic asymmetry of imprinted genes in plant gametes. Nat. Genet. 38,876–878.CrossRefGoogle Scholar
  24. Hale, C.J., Stonaker, J.L., Gross, S.M., and Hollick, J.B. (2007) A novel SNF2 protein maintains transgenerational regulatory states established by paramutation in maize. PLoS Biology (In Press)Google Scholar
  25. Haun, W.J., Laoueille-Duprat, S., O'Connell, M.J., Spillane, C., Grossniklaus, U., Phillips, A.R., Kaeppler, S.M., and Springer, N.M. (2007) Genomic imprinting, methylation and molecular evolution of maize Enhancer of Zeste (Mez) homologs. Plant J. 49, 325–337.PubMedCrossRefGoogle Scholar
  26. Henderson, I.R. and Jobsen, S.E. (2007) Epigenetic inheritance in plants. Nature 447, 418–424.PubMedCrossRefGoogle Scholar
  27. Hermon, P., Srilunchang, K.O., Zou, J., Dresselhaus, T., Danilevskaya, O.N. (2007) Activation of the imprinted Polycomb Group Fie1 gene in maize endosperm requires demethylation of the maternal allele. Plant Mol. Biol. 64, 387–395.PubMedCrossRefGoogle Scholar
  28. Hoekenga, O.A., Muszynski, M.G., and Cone, K.C. (2000) Developmental patterns of chromatin structure and DNA methylation responsible for epigenetic expression of a maize regulatory gene. Genetics 155,1889–1902.PubMedGoogle Scholar
  29. Hollick, J.B., and Chandler, V.L. (2001) Genetic factors required to maintain repression of a paramutagenic maize pl1 allele. Genetics 157,369–378.PubMedGoogle Scholar
  30. Hollick, J.B., Patterson, G.K., Coe, Jr. E.H., Cone, K.C., and Chandler, V.L. (1995) Allelic interactions heritably influence the activity of a metastable maize pl allele. Genetics 141,709–719.PubMedGoogle Scholar
  31. Huettel, B. Kanno, T., Daxinger, L., Bucher, E., van der Winden, J., Matzke, A.J.M., and Matzke, M. (2007) RNA-directed DNA methylation mediated by DRD1 and PolIVb: A versatile pathway for transcriptional gene silencing in plants. Bioch. Bioph. Acta 1769, 358–374.Google Scholar
  32. Ito, T., Bulger, M., Kobayashi, R., and Kadonaga, J.T. (1996) Drosophila NAP-1 is a core histone chaperone that functions in ATP-facilitated assembly of regularly spaced nucleosomal arrays. Mol. Cell. Biol. 16,3112–3124.PubMedGoogle Scholar
  33. Johnson, L.M., Bostick, M., Zhang, X., Kraft, E., Henderson, I., Callis, J., and Jacobsen, S.E. (2007) The SRA methyl-cytosine-binding domain links DNA and histone methylation. Current Biol. 17,379–384.CrossRefGoogle Scholar
  34. Juarez M.T., Kui, J.S., Thomas, J., Heller, B.A., Timmermans, M.C. (2004) microRNA repression of rolled leaf1 specifies maize leaf polarity. Nature 428,84–88.PubMedCrossRefGoogle Scholar
  35. Kaeppler, S.M., Kaeppler, H.F., and Rhee. Y. (2000) Epigenetic aspects of somaclonal variation in plants. Plant Molec. Biol. 43,179–188.CrossRefGoogle Scholar
  36. Kanno, T., Mette, M.F., Kreil, D.P., Aufsatz, W., Matzke, M., and Matzke, A.J.M. (2004) Involvement of putative SNF2 chromatin remodeling protein DRD1 in RNA-directed DNA methylation. Current Biology 14,801–805.PubMedCrossRefGoogle Scholar
  37. Kanno, T., Aufsatz, W., Jaligot, E., Mette, M.F., Matzke, M., and Matzke, A.J.M. (2005) A SNF2-like protein facilitates dynamic control of DNA methylation. EMBO 6,649–655.CrossRefGoogle Scholar
  38. Kermicle, J.L., Eggelston, W.B., and Alleman, M. (1995) Organization of paramutagenecity in R-stippled maize. Genetics 141,361–372.PubMedGoogle Scholar
  39. Kidner, C.A, and Martienssen, R.A. (2005) The developmental role of microRNA in plants. Curr. Opin. Plant Biol. 8, 38–44.PubMedCrossRefGoogle Scholar
  40. Kolle, D., Brosch, G., Lechner, T., Pipal, A., Helliger, W., Taplick, J., and Loidl, P. (1999) Different types of maize histone deacetylases are distinguished by a highly complex substrate and site specificity. Biochem. 38,6769–6773.CrossRefGoogle Scholar
  41. Lauria, M., Rupe, M., Guo, M., Kranz, E., Pirona, R., Viotti, A., and Lund, G. (2004) Extensive DNA hypomethylation in the endosperm of Zea mays. Plant Cell 16,510–522.PubMedCrossRefGoogle Scholar
  42. Lauter, M., Kampani, A., Carlson, S., Goebel, M., and Moose, S.P. (2005) microRNA 172 down-regulates glossy15 to promote vegetative phase change in maize. Proc. Nat'l. Acad. Sci. 102,9412–9417.CrossRefGoogle Scholar
  43. Lechner, T., Lusser, A., Pipal, A., Brosch, G., Loidl, A., Goralik-Schramel, M., Sendra, R., Wegener, S., Walton, J.D., and Loidl, P. (2000) RPD3-type histone deacetylases in maize embryos. Biochem. 39,1683–1692.CrossRefGoogle Scholar
  44. Lopez-Rodas, G., Georgieva, E.K., Sendra, R., and Loidl, P. (1991) Histone acetylation in Zea mays I: activities of histone acetyltransferases and histone deacetylases. J. Biol. Chem. 266,18745–18750.Google Scholar
  45. Lusser, A., Brosch, G., Loidl, A., Haas, H., and Loidl, P. (1997) Identification of maize histone deacetylase HD2 as an acidic nucleolar phosphoprotein. Science 277,88–91.PubMedCrossRefGoogle Scholar
  46. Makarevitch, I., Stupar, R.M., Iniguez, A.L., Haun, W.J., Barbazuk, W.B., Kaeppler, S.M., and Spinger, N.M. (2007) Natural variation for alleles under epigenetic control by the maize chro-momethylase zmet 2. Genetics 177,1–12.CrossRefGoogle Scholar
  47. Mallory, C.A., and Vaucheret, H. (2006) Functions of microRNAs and related small RNAs in plants. Nat. Genet. 38,S31–S36.PubMedCrossRefGoogle Scholar
  48. Marian, C.O., Bordoli, S.J., Goltz, M., Santarella, R.A., Jackson, L.P., Danilevskaya, O., Beckstette, M., Meeley, R., and Bass, H.W. (2003) The maize Single myb histone 1 gene, Smh1, belongs to a novel gene family and encodes a protein that binds telomere DNA repeats in vitro. Plant Physiol. 133,1336–1350.PubMedCrossRefGoogle Scholar
  49. Martienssen, R. and Baron, A. (1994) Coordinate suppression of mutations caused by Robertson's mutator transposons in maize. Genetics 136,1157–1170.PubMedGoogle Scholar
  50. McGinnis, K.M., Chandler, V., Cone, K., Kaeppler, H., Kaeppler, S., Kerschen, A., Pikaard, C., Richards, E., Sidorenko, L., Smith, T., Springer, N., and Wulan, T. (2006a) Transgene-induced RNA interference as a tool for plant functional genomics. Meth. Enzymol. 392,1–24.CrossRefGoogle Scholar
  51. McGinnis, K.M., Springer, C., Lin, Y., Carey, C.C., and Chandler, V. (2006b) Transcriptionally silenced transgenes in maize are activated by three mutations defective in paramutation. Genetics 173,1627–1647.CrossRefGoogle Scholar
  52. McGinnis, K.M., Murphy, N., Carlson, A.R., Akula, A., Akula, C., Basinger, H., Carlson, M., Hermanson, P., Kovacevic, N., McGill, M.A., Seshadri, V., Yoyokie, J., Cone, K., Kaeppler, H.F., Kaeppler, S.M., and Springer, N.M. (2007) Assessing the efficiency of RNA interference for maize functional genomics. Plant Physiol. 143,1441–1451.PubMedCrossRefGoogle Scholar
  53. Ng, D.W-K., Want, T., Chandrasekharan, M.B., Aramayo, R., Kertbundit, S., and Hall, T.C. (2007) Plant SET domain-containing proteins: structure, function, and regulation. Biochim. Biophys. Acta 1769,316–329.PubMedGoogle Scholar
  54. Nogueira, F.T., Madi, S., Chitwood, D.H., Juarez M.T., and Timmermans, M.C. (2007) Two small regulatory RNAs establish opposing fates of a developmental axis. Genes Devel. 21,750–755.PubMedCrossRefGoogle Scholar
  55. Ohad, N., Yadegari, R., Margossian, L., Hannon, M., Michaeli, D., Harada, J.J., Goldberg, R.B., Fischer, R.L. (1999) Mutations in RIE, a WD polycomb group gene, allow endosperm development without fertilization. Plant Cell 11,407–416.PubMedCrossRefGoogle Scholar
  56. Papa, C.M., Springer, N.M., Muszynski, M.G., Meeley, R., and Kaeppler, S.M. (2001) Maize chromomethylase Zea methyltransferase2 is required for CpNpG methylation. Plant Cell 13,1919–1928.PubMedCrossRefGoogle Scholar
  57. Pandey, R., Muller, A., Napoli, C.A., Selinger, D.A., Pikaard, C.S., Richards, E.J., Bender, J., Mount, D.W., and Jorgenson, R.A. (2002) Analysis of histone acetyltransferase and histone deacetylase families in Arabidopsis thaliana suggests functional diversification of chromatin modification among multicellular eukaryotes. Nucl. Acids Res. 30,5036–5055.PubMedCrossRefGoogle Scholar
  58. Parkinson, W.C., Gross, S.M., and Hollick, J.B. (2007) Maize sex determination and abaxial leaf fates are canalized by a factor that maintains repressed epigenetic states. Dev. Biol. 308,462–473.PubMedCrossRefGoogle Scholar
  59. Pavlopoulou, A. and Kossida, S. (2007) Plant cytosine-5 DNA methyltransferases: Structure, function, and molecular evolution. Genomics 90,530–541.PubMedCrossRefGoogle Scholar
  60. Phelps-Durr, T.L., Thomas, J., Vahab, P., and Timmermans, M.C.P. (2005) Maize rough sheath 2 and its Arabidopsis ortholog ASYMMETRIC LEAVES 1 interact with HIRA, a predicted histone chaperone, to maintain knox, gene silencing and determinacy during organogenesis. Plant Cell 17,2886–2898.CrossRefGoogle Scholar
  61. Pikaard, C.S. (2006) Cell biology of the Arabidopsis nuclear siRNA pathway for RNA-directed chromatin modification. Cold Spring Harbor Symp. Quant. Biol. 71:473–480.PubMedCrossRefGoogle Scholar
  62. Pipal, A., Goralik-Schramel, M., Lusser, A., Lanzanova, C., Sarg, B., Loidl, A., Lindner, H., Rossi, V., Loidl, P. (2003) Regulation and processing of maize histone deacetylase Hda1 by limited proteolysis. Plant Cell 15,1904–1917.PubMedCrossRefGoogle Scholar
  63. Pressman, S., Bei, Y., and Carthew, R. (2007). Snapshot: Posttranscriptional gene silencing. Cell 130:570.PubMedCrossRefGoogle Scholar
  64. Rabinowicz, P.D., Citek, R., Budiman, M.A., Nunberg, A., Bedell, J.A., Lakey, N., O'Shaughnessy, A.L., Nascimento, L.U., McCombie, W.R., and Martienssen, R.A. (2005) Differential methylation of genes and repeats in land plants. Genome Res. 15,1431–1440.PubMedCrossRefGoogle Scholar
  65. Rossi, V., Locatelli, S., Lanzanova, C., Boniotti, M.B., Varotto, S., Pipal, A., Goralik-Schramel, M., Lusser, A., Gatz, C., Guttierrez, C., and Motto, M. (2003) A maize histone deacetylase and retinoblastoma-related protein physically interact and cooperate in repressing gene function. Plant Molec. Biol. 51,401–413.CrossRefGoogle Scholar
  66. Rossi, V., Locatelli, S., Varotto, S., Donn, G., Pirona, R., Henderson, D.A., Hartings, H., and Motto, M. (2007) Maize histone deacetylase hda101 is involved in plant development, gene transcription, and sequence-specific modulation of histone modification of genes and repeats. Plant Cell 19,1145–1162.PubMedCrossRefGoogle Scholar
  67. Rossi, V., Varotto, S., Locatelli, S., Lanzanova, C., Lauria, M., Zanotti, E., Hartings, H., and Motto, M. (2001) The maize WD-repeat gene ZmRbAp1 encodes a member of the MSI/RbAp sub-family and is differentially expressed during endosperm development. Mol. Genet. Genomics 265,576–584.PubMedCrossRefGoogle Scholar
  68. Rudenko, G.N., Ono, A., and Walbot, V. (2003) Initiation of silencing of maize MuDR/Mu transposable elements. Plant J. 33,1013–1025.PubMedCrossRefGoogle Scholar
  69. Schwartz, D. (1989) Gene-controlled cytosine demethylation in the promoter region of the Ac element of maize. Proc. Nat'l. Acad. Sci. USA 86,2789–2793.CrossRefGoogle Scholar
  70. Segal, G., Song, R., and Messing, J. (2003) A new opaque variant of maize by a single dominant RNA-interference-inducing transgene. Genetics 165,387–397.PubMedGoogle Scholar
  71. Sekhon, R.S., Peterson, T., and Chopra, S. (2007) Epigenetic modifications of distinct sequences of the pl regulatory gene specify tissue-specific expression patterns in maize. Genetics 175,1059–1070.PubMedCrossRefGoogle Scholar
  72. Shi, J. and Dawe, R.K. (2006) Partitioning of the maize epigenome by the number of methyl groups on histone H3 lysines 9 and 27. Genetics 173,1571–1583.PubMedCrossRefGoogle Scholar
  73. Sidorenko, L.V. and Peterson, T. (2001) Transgene-induced silencing identifies sequences involved in the establishment of paramutation of the maize p1 gene. Plant Cell 13,319–335.PubMedCrossRefGoogle Scholar
  74. Slotkin, R.K., Freeling, M., and Lisch, D. (2003) Mu killer causes the heritable inactivation of the Mutator family of elements in Zea mays. Genetics 165,781–797.PubMedGoogle Scholar
  75. Smith, L.M., Pontes, O., Searle, I., Yelina, N., Yousafzai, F.K., Herr, A.J., Pikaard, C.S., and Baulcombe, D.C. (2007) An SNF2 protein associated with nuclear RNA silencing and the spread of a silencing signal between cells in Arabidopsis. Plant Cell 19:1507–1521.PubMedCrossRefGoogle Scholar
  76. Spector, M.S., Raff, A., DeSilva, H., Lee, K., and Osley, M.A. (1997) Hir1p and Hir2p function as transcriptional corepressors to regulate histone gene transcription in the Saccharomyces cereviseae cell cycle. Mol. Cell. Biol. 17,545–552.PubMedGoogle Scholar
  77. Springer, N.M., Danilevskaya, O.N., Hermon, P., Helentjaris, T.G., Phillips, R.L., Kaeppler, H.F., and Kaeppler, S.M. (2002) Sequence relationships, conserved domains, and expression patterns for maize homologs of the polycomb group genes E(z), esc, and E(Pc). Plant Physiol. 128,1332–1345.PubMedCrossRefGoogle Scholar
  78. Springer, N.M., and Kaeppler, S.M. (2005) Evolutionary divergence of monocot and dicot methyl- CpG-binding domain proteins. Plant Physiol. 138,92–104.PubMedCrossRefGoogle Scholar
  79. Springer, N.M., Napoli, C.A., Selinger, D.A., Pandey, R., Cone, K.C., Chandler, V.L., Kaeppler, H.F., and Kaeppler, S.M. (2003) Comparative analysis of SET domain proteins in maize and Arabidopsis reveals multiple duplications preceding the divergence of monocots and dicots. Plant Physiol. 132,907–925.PubMedCrossRefGoogle Scholar
  80. Stam, M., Belele, C., Dorweiler, J.E., and Chandler, V.L. (2002) Differential chromatin structure within a tandem array 100 kb upstream of the maize b1 locus is associated with paramutation. Genes Develop. 16,1906–1912.PubMedCrossRefGoogle Scholar
  81. Steward, N., Ito, M., Yamaguchi, Y., Koizumi, N., and Sano, H. (2002) Periodic DNA methylation in maize nucleosomes and demethylation by environmental stress. J. Biol. Chem. 277, 37741–37746.PubMedCrossRefGoogle Scholar
  82. Steward, N., Kusano, T., and Sano, H. (2000) Expression of ZmMet1, a gene encoding a DNA methyltransferase from maize, is associated not only with DNA replication in actively proliferating cells, but also with altered DNA methylation status in cold-stressed quiescent cells. Nucl. Acids Res. 28,3250–3259.PubMedCrossRefGoogle Scholar
  83. Sunkar, R., Viswanathan, C., Zhu, J., and Zhu, J-K. (2007) Small RNAs as big players in plant abiotic stress responses and nutrient deprivation. Trends in Plant Science 12, 301–309.PubMedCrossRefGoogle Scholar
  84. Varotto, S., Locatelli, S., Canova, S., Pipal, A., Motto, M., and Rossi, V. (2003) Expression profile and cellular localization of maize Rpd3-type histone deacetylases during plant development. Plant Physiol. 133,606–617.PubMedCrossRefGoogle Scholar
  85. Vongs, A., Kakutani, T., Martienssen, R.A., and Richards, E.J. (1993) Arabidopsis thaliana DNA methylation mutants. Science 260, 1926–1928.PubMedCrossRefGoogle Scholar
  86. Walker, E.L. (1998) Paramutation of the r1 locus of maize is associated with increased cytosine methylation. Genetics 148,1973–1981.PubMedGoogle Scholar
  87. Walker, E.L. and Panavas, T. (2001) Structural features and methylation patterns associated with paramutation at the r1 locus of Zea mays. Genetics 159,1201–1215.PubMedGoogle Scholar
  88. Woo, H.R., Pontes, O., Pikaard, C.S., and Richards, E.J. (2007) VIM1, a methylcytosine-binding protein required for centromeric heterochromatinization. Genes Develop. 21,267–277.PubMedCrossRefGoogle Scholar
  89. Woodhouse, M.R., Freeling, M., and Lisch, D. (2006a) Initiation, establishment, and maintenance of heritable MuDR transposon silencing in maize are mediated by distinct factors. PLoS Biol. 4,e339.CrossRefGoogle Scholar
  90. Woodhouse, M.R., Freeling, M., and Lisch, D. (2006b) The mop1 (mediator of paramutation1) mutant progressively reactivates one of the two genes encoded by the MuDR transposon in maize. Genetics 172,579–592.CrossRefGoogle Scholar
  91. Zemach, A. and Grafi, G. (2007) Methyl-CpG-binding domain proteins in plants: interpreters of DNA methylation. Trends Plant Sci. 12,80–85.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science + Business Media, LLC 2009

Authors and Affiliations

  • Shawn Kaeppler

There are no affiliations available

Personalised recommendations