A conserved, Mg2+-dependent exonuclease degrades organelle dna during Arabidopsis pollen development

Ryo Matsushima, Lay Yin Tang, Lingang Zhang, Hiroshi Yamada, David Twell, Wataru Sakamoto

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

In plant cells, mitochondria and plastids contain their own genomes derived from the ancestral bacteria endosymbiont. Despite their limited genetic capacity, these multicopy organelle genomes account for a substantial fraction of total cellular DNA, raising the question of whether organelle DNA quantity is controlled spatially or temporally. In this study, we genetically dissected the organelle DNA decrease in pollen, a phenomenon that appears to be common in most angiosperm species. By staining mature pollen grains with fluorescent DNA dye, we screened Arabidopsis thaliana for mutants in which extrachromosomal DNAs had accumulated. Such a recessive mutant, termed defective in pollen organelle DNA degrada-tion1 (dpd1), showing elevated levels of DNAs in both plastids and mitochondria, was isolated and characterized. DPD1 encodes a protein belonging to the exonuclease family, whose homologs appear to be found in angiosperms. Indeed, DPD1 has Mg2+-dependent exonuclease activity when expressed as a fusion protein and when assayed in vitro and is highly active in developing pollen. Consistent with the dpd phenotype, DPD1 is dual-targeted to plastids and mitochondria. Therefore, we provide evidence of active organelle DNA degradation in the angiosperm male gametophyte, primarily independent of maternal inheritance; the biological function of organellar DNA degradation in pollen is currently unclear.

Original languageEnglish
Pages (from-to)1608-1624
Number of pages17
JournalPlant Cell
Volume23
Issue number4
DOIs
Publication statusPublished - Apr 2011

ASJC Scopus subject areas

  • Plant Science
  • Cell Biology

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