Abstract
Ribosomal RNA genes originating from one parent are often suppressed in interspecific hybrids. We show that treatments during germination with the cytosine analogue 5-azacytidine stably reactivate the expression of the suppressed rRNA genes of rye origin in the wheat x rye amphiploid, triticale, by preventing methylation of sites in the rye rDNA. When 5-azacytidine is applied to embryos of triticale and wheat x rye F1 hybrids nine, or more, days after fertilization, rye rRNA gene expression is stably reactivated in the resulting seedling. Earlier treatments have no effect on rye rRNA gene expression, indicating that undermethylation of DNA early in embryo development is reversible. After 9 days, the methylation status of rRNA genes in maintained throughout development. Since the change in expression follows a methylation change at particular restriction-enzyme sites, the data establish a clear correlation between gene activity and methylation in plants.
Similar content being viewed by others
References
Anamthawat-Jónsson K, Schwarzacher T, Leitch AR, Bennett MD, Heslop-Harrison JS (1990) Discrimination between closely related Triticeae species using genomic DNA as a probe. Theor Appl Genet 79:721–718
Appels R, Moran LB, Gustafson JP (1986) The structure of DNA from the rye (Secale cereale) NOR R1 locus and its behaviour in wheat backgrounds. Can J Genet Cytol 28:673–685
Barker RF, Harberd NP, Jarvis MG, Flavell RB (1988) Structure and evolution of the intergenic region in a ribosomal DNA repeat unit of wheat. J Mol Biol 201:1–17
Barlow DP (1993) Methylation and imprinting —from host defence to gene regulation. Science 260:309–310
Ferguson-Smith AC, Sasaki H, Cattanach BM, Surani MA (1993) Parental origin-specific epigenetic modification of the mouse H19 gene. Nature 362:751–755
Gerlach WL, Bedbrook JR (1979) Cloning and characterization of ribosomal RNA genes from wheat and barley. Nucleic Acids Res 7:1869–1885
Hayashibara KC, Verdine GL (1992) Template-directed interference footprinting of cytosine contacts in a protein-DNA complex: potent interference by 5-aza-2′deoxycytidine. Biochemistry 31:11265–11273
Heslop-Harrison JS (1990) Gene expression and parental dominance in hybrid plants. Development 1105:21–28
Heslop-Harrison JS, Leitch AR, Schwarzacher T, Anamthawat-Jóns- son K (1990) Detection and characterization of 1B/1R translocations in hexaploid wheat. Heredity 65:285–294
Hubbell HR (1985) Silver staining as an indicator of active ribosomal genes. Stain Technol 60:285–294
Jimenez M, Jimenez R, Burgos M, Diaz de la Espina R (1988) A study of the Ag-staining significance in mitotic NORs. Heredity 60:125–127
Jones PA (1985) Altering gene expression with 5-azacytidine. Cell 40:485–486
Lacadena JR, Cermeño MC, Orellana J (1984) Evidence for wheat-rye nucleolar competition (amphiplasty) in triticale by the silver-staining procedure. Theor Appl Genet 67:207–213
Lacadena JR, Cermeno MC, Orellana J, Santos JL (1988) Nucleolar competition in Triticeae. Kew Chrom Conf III:151–165
Navashin M (1934) Chromosomal alterations caused by hybridization and their bearing upon certain general genetic problems. Cytologia 5:169–203
Ottaviani M-P, Smits T, Hänische ten Cate C (1993) Differential methylation and expression of the beta-glucuronidase and neomysin phosphotransferase genes in transgenic plants of potato cv Bintje. Plant Sci 88:73–81
Reeder H (1985) Mechanisms of nucelolar dominance in animals and plants. J Cell Biol 101:2013–2016
Sardana R, O'Dell M, Flavell RB (1993) Correlation between the size of the intergenic regulatory region, the status of cytosine methylation of rRNA genes and nucleolar expression in wheat. Mol Gen Genet 236:155–162
Vieira R, Queiroz A, Morais L, Barao A, Mello-Sampayo T, Viegas WS (1990) 1R chromosome nucleolus organizer region activation by 5-azacytidine in wheat x rye hybrids. Genome 33:707–712
Author information
Authors and Affiliations
Additional information
Communicated by G. S. Kush
Rights and permissions
About this article
Cite this article
Neves, N., Heslop-Harrison, J.S. & Viegas, W. rRNA gene activity and control of expression mediated by methylation and imprinting during embryo development in wheat x rye hybrids. Theoret. Appl. Genetics 91, 529–533 (1995). https://doi.org/10.1007/BF00222984
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00222984