Plant Cell Reports

, Volume 36, Issue 8, pp 1277–1285 | Cite as

Dynamic nucleolar activity in wheat × Aegilops hybrids: evidence of C-genome dominance

  • Ghader MirzaghaderiEmail author
  • Zinat Abdolmalaki
  • Mohsen Zohouri
  • Zeinab Moradi
  • Annaliese S. Mason
Original Article


Key message

NOR loci of C-subgenome are dominant in wheat × Aegilops interspecific hybrids, which may have evolutionary implications for wheat group genome dynamics and evolution.


After interspecific hybridisation, some genes are often expressed from only one of the progenitor species, shaping subsequent allopolyploid genome evolution processes. A well-known example is nucleolar dominance, i.e. the formation of cell nucleoli from chromosomes of only one parental species. We studied nucleolar organizing regions (NORs) in diploid Aegilops markgrafii (syn: Ae. caudata; CC), Ae. umbellulata (UU), allotetraploids Aegilops cylindrica (CcCcDcDc) and Ae. triuncialis (CtCtUtUt), synthetic interspecific F1 hybrids between these two allotetraploids and bread wheat (Triticum aestivum, AABBDD) and in F3 generation hybrids with genome composition AABBDDCtCtUtUt using silver staining and fluorescence in situ hybridization (FISH). In Ae. markgrafii (CC), NORs of both 1C and 5C or only 5C chromosome pairs were active in different individual cells, while only NORs on 1U chromosomes were active in Ae. umbellulata (UU). Although all 35S rDNA loci of the Ct subgenome (located on 1Ct and 5Ct) were active in Ae. triuncialis, only one pair (occupying either 1Cc or 5Cc) was active in Ae. cylindrica, depending on the genotype studied. These C-genome expression patterns were transmitted to the F1 and F3 generations. Wheat chromosome NOR activity was variable in Ae. triuncialis × T. aestivum F1 seeds, but silenced by the F3 generation. No effect of maternal or paternal cross direction was observed. These results indicate that C-subgenome NOR loci are dominant in wheat × Aegilops interspecific hybrids, which may have evolutionary implications for wheat group genome dynamics and allopolyploid evolution.


Nucleolar dominance 35S rRNA gene Polyploidization Interspecific hybridization 



This research was financially supported by the University of Kurdistan, Sanandaj. The authors declare that they have no competing interests. The first author acquired some data (FISH of Ae. triuncialis and its subgenomes) at Andreas Houben’s lab at IPK, Germany. ASM is supported by DFG Emmy Noether award MA6473/1-1.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

Ethical standards

The manuscript has not been submitted to more than one journal for simultaneous consideration. No data have been fabricated or manipulated to support our conclusions. We have acknowledged and cited the work of others to the best of our knowledge. All authors read and approved the final manuscript.

Supplementary material

299_2017_2152_MOESM1_ESM.pptx (11.9 mb)
Supplementary material 1 (PPTX 12148 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  1. 1.Department of Agronomy and Plant Breeding, Faculty of AgricultureUniversity of KurdistanSanandajIran
  2. 2.Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and NutritionJustus Liebig UniversityGiessenGermany

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