Woronin body function in Magnaporthe grisea is essential for efficient pathogenesis and for survival during nitrogen starvation stress

• Published in: The Plant cell Vol. 16; no. 6; pp. 1564 - 1574
• Main Authors: Soundararajan, S, Jedd, G, Li, X, Ramos-Pamplona, M, Chua, N.H, Naqvi, N.I
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01-06-2004
• Subjects: amino acid sequences; Appressoria; barley; Base Sequence; blast disease; Blasts; cell differentiation; Cloning, Molecular; Conidia; DNA, Bacterial - genetics; Exodeoxyribonucleases - deficiency; Exodeoxyribonucleases - genetics; fungal proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungi; Gels; hex1p protein; hexagonal peroxisome protein; Hordeum - microbiology; Hordeum vulgare; Hyphae; Hyphae - cytology; Hyphae - enzymology; Hyphae - genetics; Hyphae - physiology; infection hyphae; Infections; leaves; loci; Magnaporthe - drug effects; Magnaporthe - genetics; Magnaporthe - pathogenicity; Magnaporthe - physiology; Magnaporthe grisea; messenger RNA; Molecular Sequence Data; mutants; Mutation - genetics; Nitrogen; Nitrogen - pharmacology; nucleotide sequences; nutrient deficiencies; Onions - microbiology; organelles; Oryza - microbiology; Oryza sativa; pathogenesis; Peroxisomes - enzymology; Peroxisomes - physiology; phenotype; Plant Diseases - microbiology; plant pathogenic fungi; Plants - microbiology; Rice; Starvation; structural genes; transcription (genetics); Virulence
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.020677

The Woronin body is a peroxisome-derived dense-core vesicle that is specific to several genera of filamentous ascomycetes, where it has been shown to seal septal pores in response to cellular damage. The Hexagonal peroxisome (Hex1) protein was recently identified as a major constituent of the Woronin body and shown to be responsible for self-assembly of the dense core of this organelle. Using a mutation in the Magnaporthe grisea HEX1 ortholog, we define a dual and essential function for Woronin bodies during the pathogenic phase of the rice blast fungus. We show that the Woronin body is initially required for proper development and function of appressoria (infection structures) and subsequently necessary for survival of infectious fungal hyphae during invasive growth and host colonization. Fungal mycelia lacking HEX1 function were unable to survive nitrogen starvation in vitro, suggesting that in planta growth defects are a consequence of the mutant's inability to cope with nutritional stress. Thus, Woronin body function provides the blast fungus with an important defense against the antagonistic and nutrient-limiting environment encountered within the host plant.