Recurrent sequence exchange between homeologous grass chromosomes

Thomas Wicker, Rod A Wing, Ingo Schubert

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

All grass species evolved from an ancestor that underwent a whole-genome duplication (WGD) approximately 70 million years ago. Interestingly, the short arms of rice chromosomes 11 and 12 (and independently their homologs in sorghum) were found to be much more similar to each other than other homeologous regions within the duplicated genome. Based on detailed analysis of rice chromosomes 11 and 12 and their homologs in seven grass species, we propose a mechanism that explains the apparently 'younger' age of the duplication in this region of the genome, assuming a small number of reciprocal translocations at the chromosome termini. In each case the translocations were followed by unbalanced transmission and subsequent lineage sorting of the involved chromosomes to offspring. Molecular dating of these translocation events also allowed us to date major chromosome 'fusions' in the evolutionary lineages that led to Brachypodium and Triticeae. Furthermore, we provide evidence that rice is exceptional regarding the evolution of chromosomes 11 and 12, inasmuch as in other species the process of sequence exchange between homeologous chromosomes ceased much earlier than in rice. We presume that random events rather than selective forces are responsible for the observed high similarity between the short arm ends of rice chromosomes 11 and 12. Significance Statement The ancestor of extant grass species underwent a whole-genome duplication 70 million years ago, but surprisingly two rice chromosomes seemed to contradict this age. Here we propose that reciprocal translocations at the chromosome termini, followed by unbalanced transmission of these chromosomes, explains the apparent younger age of the whole genome duplication in these chromosomal regions.

Original languageEnglish (US)
Pages (from-to)747-759
Number of pages13
JournalPlant Journal
Volume84
Issue number4
DOIs
StatePublished - Nov 1 2015

Fingerprint

Poaceae
Chromosomes
Chromosomes, Human, Pair 12
Chromosomes, Human, Pair 11
grasses
chromosomes
Genome
rice
genome
reciprocal translocation
Brachypodium
Chromosome Duplication
Sorghum
ancestry
chromosome transmission
Oryza
Sorghum (Poaceae)
sorting

Keywords

  • genome evolution
  • grass ancestor
  • inter-homeolog recombination
  • reciprocal translocation
  • whole-genome duplication

ASJC Scopus subject areas

  • Plant Science
  • Cell Biology
  • Genetics

Cite this

Recurrent sequence exchange between homeologous grass chromosomes. / Wicker, Thomas; Wing, Rod A; Schubert, Ingo.

In: Plant Journal, Vol. 84, No. 4, 01.11.2015, p. 747-759.

Research output: Contribution to journalArticle

Wicker, Thomas ; Wing, Rod A ; Schubert, Ingo. / Recurrent sequence exchange between homeologous grass chromosomes. In: Plant Journal. 2015 ; Vol. 84, No. 4. pp. 747-759.
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