A putative DEAD-box RNA-helicase is required for normal zoospore development in the late blight pathogen Phytophthora infestans

Claire A. Walker, Maico Koppe, Laura J. Grenville-Briggs, Anna O. Avrova, Neil R. Horner, Alastair D. McKinnon, Stephen C. Whisson, Paul R. J. Birch, Pieter van West

Research output: Contribution to journalArticle

24 Citations (Scopus)


The asexual multinucleated sporangia of Phytophthora infestans can germinate directly through a germ tube or indirectly by releasing zoospores. The molecular mechanisms controlling sporangial cytokinesis or sporangial cleavage, and zoospore release are largely unknown. Sporangial cleavage is initiated by a cold shock that eventually compartmentalizes single nuclei within each zoospore. Comparison of EST representation in different cDNA libraries revealed a putative ATP-dependent DEAD-box RNA-helicase gene in P. infestans, Pi-RNH1, which has a 140-fold increased expression level in young zoospores compared to uncleaved sporangia. RNA interference was employed to determine the role of Pi-RNH1 in zoospore development. Silencing efficiencies of up to 99% were achieved in some transiently-silenced lines. These Pi-RNH1-silenced lines produced large aberrant zoospores that had undergone partial cleavage and often had multiple flagella on their surface. Transmission electron microscopy revealed that cytoplasmic vesicles fused in the silenced lines, resulting in the formation of large vesicles. The Pi-RNH1-silenced zoospores were also sensitive to osmotic pressure and often ruptured upon release from the sporangia. These findings indicate that Pi-RNH1 has a major function in zoospore development and its potential role in cytokinesis is discussed. (c) 2008 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)954-962
Number of pages9
JournalFungal Genetics and Biology
Issue number6
Early online date20 Mar 2008
Publication statusPublished - Jun 2008


  • Phytophthora infestans
  • oomycete
  • RNA-helicase
  • zoospore
  • pathogen
  • development
  • protein-synthesis
  • sporangial cleavage
  • potato infection
  • gene
  • germination
  • palmivora
  • calcium
  • transcription
  • cytokines
  • activation


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