Preferential elimination of repeated DNA sequences from the paternal, Nicotiana tomentosiformis genome donor of a synthetic, allotetraploid tobacco

New Phytol. 2005 Apr;166(1):291-303. doi: 10.1111/j.1469-8137.2004.01297.x.

Abstract

Nicotiana tabacum (tobacco, 2n = 4x = 48) is a natural allotetraploid combining two ancestral genomes closely related to modern Nicotiana sylvestris and Nicotiana tomentosiformis. Here we examine the immediate consequences of allopolyploidy on genome evolution using 20 S4-generation plants derived from a single synthetic, S0 plant made by Burk in 1973 (Th37). Using molecular and cytogenetic methods we analysed 14 middle and highly repetitive sequences that together total approximately 4% of the genome. Two repeats related to endogenous geminiviruses (GRD5) and pararetroviruses (NtoEPRV), and two classes of satellite repeats (NTRS, A1/A2) were partially or completely eliminated at variable frequency (25-60%). These sequences are all from the N. tomentosiformis parent. Genomic in situ hybridization revealed additivity in chromosome numbers in two plants (2n = 48), while a third was aneuploid for an N. tomentosiformis-origin chromosome (2n = 49). Two plants had homozygous translocations between chromosomes of the S- and T-genomes. * The data demonstrate that genetic changes in synthetic tobacco were fast, targeted to the paternal N. tomentosiformis-donated genome, and some of the changes showed concordance with changes that presumably occurred during evolution of natural tobacco.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Evolution
  • Crosses, Genetic
  • DNA, Plant / analysis
  • DNA, Plant / genetics*
  • DNA, Ribosomal
  • DNA, Viral / genetics
  • Genome, Plant
  • Interspersed Repetitive Sequences
  • Karyotyping
  • Plant Viruses / genetics
  • Polyploidy*
  • Tandem Repeat Sequences
  • Tobacco / genetics*

Substances

  • DNA, Plant
  • DNA, Ribosomal
  • DNA, Viral