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Sequence-variable mosaics: composites of recurrent transposition characterizing the genomes of phylogenetically

Rasa Jomantiene1, Yan Zhao, Robert E Davis

  • 1Institute of Botany, Vilnius, Lithuania.

DNA and Cell Biology
|August 11, 2007
PubMed

Insights

Phytoplasmas exhibit unique genome structures called sequence-variable mosaics (SVMs). These ancient, rapidly evolving regions are key to phytoplasma pathogenicity and host interactions.

Area of Science:

  • Microbiology
  • Genomics
  • Plant Pathology

Background:

  • Phytoplasmas are plant and insect pathogens lacking cell walls and pure culture isolation methods.
  • The 'Candidatus species' convention is used due to cultivation challenges.
  • Understanding phytoplasma genome architecture is crucial for deciphering their pathogenicity.

Purpose of the Study:

  • To investigate the genome architecture of phytoplasmas, focusing on sequence-variable mosaics (SVMs).
  • To determine the evolutionary origins and recent diversification of SVMs.
  • To identify proteins encoded by SVMs and their potential role in host interactions.

Main Methods:

  • Phylogenetic analysis of diverse phytoplasma species.
  • Comparative genomics to identify clustered genes and repetitive elements.
  • Sequence analysis of hypervariable regions within SVMs.

Main Results:

  • Multiple sequence-variable mosaics (SVMs) are characteristic of diverse phytoplasma genomes.
  • SVMs originated early in phytoplasma evolution and have undergone recent, dramatic changes.
  • Rapid evolution of SVMs involves mobile element capture, recombination, and rearrangement.
  • Hypervariable regions encode proteins like lysophospholipase, potentially involved in host interactions.

Conclusions:

  • SVMs are ancient, dynamic genomic features shaped by mobile element activity.
  • The composite structure of SVMs reflects multiple evolutionary events.
  • Proteins encoded by SVMs, particularly those at the cell surface, are significant for phytoplasma pathogenicity and host interactions.

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