, Volume 256, Issue 1, pp 227–235 | Cite as

45S rDNA sites in meiosis of Lolium multiflorum Lam.: variability, non-homologous associations and lack of fragility

  • Laiane Corsini Rocha
  • Marco Túlio Mendes Ferreira
  • Isabela Martinez Fontes Cunha
  • Andréa Mittelmann
  • Vânia Helena TechioEmail author
Original Article


In this study, we evaluated the behavior of 45S ribosomal DNA (rDNA) sites during the meiosis of Lolium multiflorum. The reason to study it in this species is that 45S rDNA sites are usually visualized as gaps in mitotic metaphase chromosomes and were initially denominated fragile sites (FSs). In different species, FSs were related to rearrangements that alter the karyotype and affect the chromosome pairing in meiosis. However, our findings show that the chromosome pairing in L. multiflorum is regular and, as in mitosis, the number of sites is variable. In diakinesis with five sites, one of the bivalents was in hemizygous state while, in diakinesis with seven sites, one of the bivalents had three conspicuous signals, two in syntheny in one of the homologous. Only four cells had gaps in the region of the 45S rDNA. Owing to the lower number of signals observed at the initial stages of meiosis, it is assumed that they are involved both in homologous and non-homologous associations and that they might assist the chromosome pairing. Regarding segregation, only meiocytes with five and six 45S rDNA signals were observed, and they were characterized by the segregation of 2/3 signals in the poles of anaphases I up to metaphases II; 2/2 and 3/3 in anaphases II and telophases II; and also 2/2 and 4/4 in the nuclei of tetrads, unlike the number of 45S signals expected. The numerical non-equivalence of sites among nuclei at later stages of meiosis is explained by the presence of chromosomes with hemizygous sites.


Fragile sites Hemizygosis Syntheny of rDNA genes Forage grasses Chromosome segregation 



The authors are thankful to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the financial support to the research and the scholarship provided and PhD Luiz Carlos de Almeida Rodrigues for his contribution in image processing.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. Armstrong SJ, Franklin FCH, Jones GH (2001) Nucleolus-associated telomere clustering and pairing precede meiotic chromosome synapsis in Arabidopsis thaliana. J Cell Sci 114:4207–4217Google Scholar
  2. Bustamante FO, Rocha LC, Torres GA, Davide LC, Mittelmann A, Techio VH (2014) Distribution of rDNA in diploid and polyploid Lolium multiflorum Lam. and fragile sites in 45S rDNA regions. Crop Sci 54:1–9. CrossRefGoogle Scholar
  3. Bustamante FO, Rocha LC, Santos NS, Silveira RAD, Nunes RC, Mittelmann A, Techio VH (2015) Analysis of nuclear DNA content and chromosome number for screening genotypes and crosses in annual ryegrass (‘Lolium multiflorum’ Lam.). Aust J Crop Sci 9(7):666Google Scholar
  4. Carvalho A, Delgado M, Barão A, Frescatada M, Ribeiro E, Pikaard CS, Viegas W, Neves N (2010) Chromosome and DNA methylation dynamics during meiosis in the autotetraploid Arabidopsis arenosa. Sex Plant Reprod 23(1):29–37. CrossRefGoogle Scholar
  5. Dong F, Song J, Naess SK, Helgeson JP, Gebhardt C, Jiang J (2000) Development and applications of a set of chromosome-specific cytogenetic DNA markers in potato. Theor Appl Genet 101:1001–1007. CrossRefGoogle Scholar
  6. Dvořáčková M, Fojtová M, Fajkus J (2015) Chromatin dynamics of plant telomeres and ribosomal genes. Plant J 83(1):18–37. CrossRefGoogle Scholar
  7. Glover TW (2006) Common fragile sites. Cancer Lett 232:4–12CrossRefGoogle Scholar
  8. Grabowska-Joachimiak A, Kula A, Gernand-Kliefoth D, Joachimiak AJ (2015) Karyotype structure and chromosome fragility in the grass Phleum echinatum host. Protoplasma 252:301–306. CrossRefGoogle Scholar
  9. Guerra M, Souza MJ (2002) Como Observar Cromossomos: um guia de técnica em citogenética vegetal, animal e humana. Funpec, São PauloGoogle Scholar
  10. Huang J, Ma L, Yang F, S-z F, Li L (2008) 45S rDNA regions are chromosome fragile sites expressed as gaps in vitro on metaphase chromosomes of root-tip meristematic cells in Lolium spp. PLoS One 3:e2167. CrossRefGoogle Scholar
  11. Huang J, Ma L, Sundararajan S, Fei S-Z, Li L (2009) Visualization by atomic force microscopy and FISH of the 45S rDNA gaps in mitotic chromosomes of Lolium perenne. Protoplasma 236:59–65. CrossRefGoogle Scholar
  12. Jiang L, Xia M, Strittmatter LI, Makaroff CA (2007) The Arabidopsis cohesin protein SYN3 localizes to the nucleolus and is essential for gametogenesis. Plant J 50(6):1020–1034. CrossRefGoogle Scholar
  13. Kobayashi T (2006) Strategies to maintain the stability of the ribosomal RNA genes repeats—collaboration of recombination, cohesion and condensation. Genes Genet Syst 81:155–161. CrossRefGoogle Scholar
  14. Ksiazczyk T, Taciak M, Zwierzykowski Z (2010) Variability of ribosomal DNA sites in Festuca pratensis, Lolium perenne, and their intergeneric hybrids, revealed by FISH and GISH. J Appl Genet 51:449–460CrossRefGoogle Scholar
  15. Lan H, Chen CL, Miao Y, Yu CX, Guo WW, Xu Q, Deng XX (2016) Fragile sites of ‘Valencia’ sweet Orange (Citrus sinensis) chromosomes are related with active 45S rDNA. PLOS One e0151512.
  16. Lideikytë L, Pašakinskienė I, Lemežienė N, Nekrošas S, Kanapeckas J (2008) FISHassessment of ribosomal DNA sites in the chromosome sets of Lolium, Festuca and Festulolium. Agriculture 265:116–124Google Scholar
  17. Mainiero S, Pawlowski WP (2014) Meiotic chromosome and structure and functions in plants. Cytogenet and Genome Res 143(1–3):6–17. CrossRefGoogle Scholar
  18. Pecinka A, Schubert V, Meister A, Kreth G, Klatte M, Lysak MA, Fuchs J, Schubert I (2004) Chromosome territory arrangement and homologous pairing in nuclei of Arabidopsis thaliana are predominantly random except for NOR-bearing chromosomes. Chromosoma 113:258–269. CrossRefGoogle Scholar
  19. Rabitsch KP, Petronczki M, Javerzat JP, Genier S, Chwalla B, Schleiffer A, Tanaka TU, Nasmyth K (2003) Kinetochore recruitment of two nucleolar proteins is required for homolog segregation in meiosis I. Dev Cell 4:535–548. CrossRefGoogle Scholar
  20. Richards RI (2001) Fragile and unstable chromosomes in cancer: causes and consequences. Trends Genet 17:339–345. CrossRefGoogle Scholar
  21. Rocha LC, de Oliveira BF, Silveira RA, Torres GA, Mittelmann A, Techio VH (2015) Functional repetitive sequences and fragile sites in chromosomes of Lolium perenne L. Protoplasma 252:451–460. CrossRefGoogle Scholar
  22. Rocha LC, Mittelmann A, Houben A, Techio VH (2016) Fragile sites of 45S rDNA of Lolium multiflorum are not hotspots for chromosomal breakages induced by X-ray. Mol Biol Rep 43:659–665. CrossRefGoogle Scholar
  23. Rocha LC, Jankowska M, Fuchs J, Mittelmann A, Techio VH, Houben A (2017a) Decondensation of chromosomal 45S rDNA sites in Lolium and Festuca genotypes does not result in karyotype instability. Protoplasma 254:285–292. CrossRefGoogle Scholar
  24. Rocha LC, Silva GA, Bustamante FO, Silveira RAD, Mittelmann A, Techio VH (2017b) Dynamics of 45S rDNA sites in the cell cycle: fragile sites and chromosomal stability in Lolium and Festuca. Genet Mol Res 16(1):gmr16019156CrossRefGoogle Scholar
  25. Thomas HM, Harper JA, Meredith MR, Morgan WG, Thomas ID, Timms E, King IP (1996) Comparasion of ribosomal DNA sites in Lolium species by fluorescence in situ hybridization. Chromosom Res 4:486–490CrossRefGoogle Scholar
  26. Thomas HM, Harper JA, Morgan WG (2001) Gross chromosome rearrangements are occurring in an accession of the grass Lolium rigidum. Chromosom Res 9:585–590CrossRefGoogle Scholar
  27. Waminal NE, Ryu KH, Choi SH, Kim HH (2013) Randomly detected genetically modified (GM) maize (Zea mays L.) near a transport route revealed a fragile 45S rDNA phenotype. PLoS One 8:e74060CrossRefGoogle Scholar
  28. Yamada T, Ohta K (2013) Initiation of meiotic recombination in chromatin structure. J Biochem 154:107–114. CrossRefGoogle Scholar
  29. Yang X, Timofejeva L, Ma H, Makaroff CA (2006) The Arabidopsis SKP1 homolog ASK1 controls meiotic chromosome remodeling and release of chromatin from the nuclear membrane and nucleolus. J Cell Sci 119(18):3754–3763. CrossRefGoogle Scholar
  30. Yuan L, Yang X, Ellis JL, Fisher NM, Makaroff CA (2012) The Arabidopsis SYN3 cohesin protein is important for early meiotic events. DOI 71:147–160. Google Scholar
  31. Yudkin D, Hayward BE, Aladjem MI, Kumari D, Usdin K (2014) Chromosome fragility and the abnormal replication of the FMR1 locus in fragile X syndrome. Hum Mol Genet 23:2940–2952. CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of BiologyFederal University of Lavras—UFLALavrasBrazil
  2. 2.Embrapa Gado de Leite/Embrapa Clima TemperadoPelotasBrazil

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