The model plant Medicago truncatula exhibits biparental plastid inheritance

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Abstract

The plastid, which originated from the endosymbiosis of a cyanobacterium, contains its own plastid DNA (ptDNA) that exhibits a unique mode of inheritance. Approximately 80% of angiosperms show maternal inheritance, whereas the remainder exhibit biparental inheritance of ptDNA. Here we studied ptDNA inheritance in the model legume, Medicago truncatula. Cytological analysis of mature pollen with DNA-specific fluorescent dyes suggested that M. truncatula is one of the few model plants potentially showing biparental inheritance of ptDNA. We further examined pollen by electron microscopy and revealed that the generative cell (a mother of sperm cells) indeed has many DNA-containing plastids. To confirm biparental inheritance genetically, we crossed two ecotypes (Jemalong A17 and A20), and the transmission mode of ptDNA was investigated by a PCR-assisted polymorphism. Consistent with the cytological observations, the majority of F1 plants possessed ptDNAs from both parents. Interestingly, cotyledons of F1 plants tended to retain a biparental ptDNA population, while later emergent leaves tended to be uniparental with either one of the parental plastid genotypes. Biparental transmission was obvious in the F2 population, in which all plants showed homoplasmy with either a paternal or a maternal plastid genotype. Collectively, these data demonstrated that M. truncatula is biparental for ptDNA transmission and thus can be an excellent model to study plastid genetics in angiosperms.

Original languageEnglish
Pages (from-to)81-91
Number of pages11
JournalPlant and Cell Physiology
Volume49
Issue number1
DOIs
Publication statusPublished - Jan 2008

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Keywords

  • Biparental inheritance
  • Medicago truncatula
  • Model plant
  • Plastid
  • Pollen grain

ASJC Scopus subject areas

  • Plant Science
  • Physiology
  • Cell Biology

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