Plant Systematics and Evolution

, Volume 144, Issue 3–4, pp 291–305

Mobile nucleolus organizing regions (NORs) inAllium (Liliaceae s. lat.)? — Inferences from the specifity of silver staining

  • Ingo Schubert


NORs and interphase nucleoli have been silver stained inAllium cepa, A. fistulosum, reciprocal crosses between both species, and in different strains of top onions which originated from hybridization betweenA. cepa andA. fistulosum. The variability observed in size, number, and position of active NORs and correspondingly in number (and size) of interphase nucleoli is at least in part strain-specific. These data are taken to indicate that NORs inAllium behave like movable genetic elements.—With respect to the staining specifity of silver nitrate, it was found that AgNO3 labels (1) nucleoli, (2) NORs (i.e., actively transcribed “ribosomal genes”) inside the achromatic secondary constrictions, and (3) sometimes (but less pronounced) centromeres; Giemsa banding labels heterochromatin surrounding the NOR but not the nucleolus organizing secondary constriction.

Key words

Angiosperms Liliaceae Alliaceae Allium cepa A. fistulosum A. ×proliferum Nucleolus organizing regions (NORs) silver staining ribosomal DNA movable genetic elements 


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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Ingo Schubert
    • 1
  1. 1.Zentralinstitut für Genetik und KulturpflanzenforschungAkademie der Wissenschaften der DDRGaterslebenGerman Democratic Republic

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