Adaptive ribosomal DNA polymorphism in wild barley at a mosaic microsite, Newe Ya'ar in Israel

Pushpendra Kumar Gupta, Shailendra Sharma, Sundip Kumar, Harindra Singh Balyan, Alex Beharav, Eviatar Nevo

Research output: Contribution to journalArticlepeer-review

Abstract

In eukaryotic genomes, ribosomal DNA is organized in tandem repeat units at the nucleolar organizing regions (NORs) on each satellited chromosome. Each repeat unit consists of a coding region and an intergenic spacer (IGS), the latter generally varying in length at different loci of the same genotype and also at the same locus in different genotypes. The spacer length variants (slvs) are sometimes correlated with climatic and ecological variables. In a study of 42 accessions of wild barley (Hordeum spontaneum) collected from four different microniches (sun-deep soil, sun-shallow soil, shade-deep soil and shade-shallow soil) at the Newe Ya'ar microsite (3182m2), in Israel, we observed eight slvs constituting 10 different rDNA phenotypes, correlated with edaphic conditions prevalent at the four microniches. We conclude that rDNA diversity in wild barley is distributed nonrandomly and adaptively in the four microniches of Newe Ya'ar. A novel feature in this study is also the homogenization of IGS length at the two loci located at two nonhomologous chromosomes. Fluorescence in situ hybridization (FISH), was used to rule out the possibility of loss of one of the two NOR loci.

Original languageEnglish
Pages (from-to)1555-1563
Number of pages9
JournalPlant Science
Volume166
Issue number6
DOIs
StatePublished - Jun 2004

Bibliographical note

Funding Information:
Financial assistance was received for this work from the Council of Scientific and Industrial Research (CSIR) New Delhi by PKG and SS, from the Department of Science and Technology (DST) New Delhi by SK, and from the Israel Discount Chair of Evolutionary Biology and the Ancell-Teicher Research Foundation for Genetics and Molecular Evolution to EN.

Keywords

  • Homogenization
  • Hordeum spontaneum
  • Natural selection
  • rDNA
  • Spacer length variants

ASJC Scopus subject areas

  • Genetics
  • Agronomy and Crop Science
  • Plant Science

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