Plant Molecular Biology

, Volume 15, Issue 3, pp 465–474

Length heterogeneity of the rRNA precursor in cucumber (Cucumis sativus)

  • U. Zentgraf
  • M. Ganal
  • V. Hemleben
Article

DOI: 10.1007/BF00019163

Cite this article as:
Zentgraf, U., Ganal, M. & Hemleben, V. Plant Mol Biol (1990) 15: 465. doi:10.1007/BF00019163

Abstract

The length homogeneous part of the intergenic spacer (IGS) of the 18S–25S ribosomal RNA genes of cucumber (Cucumis sativus) was characterized by sequencing 2389 bp preceding the 18S rRNA coding region of a 12.5 kbp repeat type. This part of the IGS is composed of repeated elements and shows a very complex structural organization. Most obvious is a 119 bp element which is repeated seven times. A single transcription initiation site (TIS) was detected by a ‘T4 polymerase stop’ experiment upstream of these repetitions giving rise to a 2013 bp 5′ external transcribed spacer (ETS) for cucumber. Nuclease mapping showed several transcription termination sites (TTS): the first one is located 350 bp downstream of the 25S rRNA coding region, the others are found within the duplications of this region accounting for the length heterogeneity of cucumber rDNA [7]. Therefore, the TTS is repeated two or three times in the IGS depending on the length of the respective repeat classes and the rRNA precursor is heterogeneous in length varying from approx. 8000 to 11000 nts.

Key words

cucumber (Cucumis sativusribosomal RNA precursor transcription initiation site (TIS) transcription termination site (TTS) external transcribed spacer (ETS) 

Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • U. Zentgraf
    • 1
  • M. Ganal
    • 1
  • V. Hemleben
    • 1
  1. 1.Lehrstuhl für Allgemeine GenetikBiologisches Institut der Universität TübingenTübingenFRG
  2. 2.Department of Plant Breeding and BiometryCornell UniversityIthacaUSA

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