Conidial Morphogenesis and Septin-Mediated Plant Infection Require Smo1, a Ras GTPase-Activating Protein in Magnaporthe oryzae

Michael J. Kershaw, Magdalena Basiewicz, Darren M. Soanes, Xia Yan, Lauren S. Ryder, Michael Csukai, Miriam Oses-Ruiz, Barbara Valent, Nicholas J. Talbot

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)
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Abstract

The pathogenic life cycle of the rice blast fungus Magnaporthe oryzae involves a series of morphogenetic changes, essential for its ability to cause disease. The smo mutation was identified > 25 years ago, and affects the shape and development of diverse cell types in M. oryzae, including conidia, appressoria, and asci. All attempts to clone the SMO1 gene by map-based cloning or complementation have failed over many years. Here, we report the identification of SMO1 by a combination of bulk segregant analysis and comparative genome analysis. SMO1 encodes a GTPase-activating protein, which regulates Ras signaling during infection-related development. Targeted deletion of SMO1 results in abnormal, nonadherent conidia, impaired in their production of spore tip mucilage. Smo1 mutants also develop smaller appressoria, with a severely reduced capacity to infect rice plants. SMO1 is necessary for the organization of microtubules and for septin-dependent remodeling of the F-actin cytoskeleton at the appressorium pore. Smol physically interacts with components of the Ras2 signaling complex, and a range of other signaling and cytoskeletal components, including the four core septins. SMO1 is therefore necessary for the regulation of RAS activation required for conidial morphogenesis and septin-mediated plant infection.

Original languageEnglish
Pages (from-to)151-167
Number of pages17
JournalGenetics
Volume211
Issue number1
Early online date16 Nov 2018
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • Magnaporthe oryzae
  • Pyricularia oryzae
  • rice blast
  • Smo
  • Ras-Gap
  • bulked segregant analysis
  • RICE BLAST FUNGUS
  • SURFACE ATTACHMENT
  • MAP KINASE
  • IDENTIFICATION
  • GRISEA
  • Norwich
  • ENCODES
  • BIOLOGY
  • GENOME
  • GROWTH

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