title: Tissue-adapted invasion strategies of the rice blast fungus Magnaporthe oryzae.
abstract: Magnaporthe oryzae causes rice blast, the most serious foliar fungal disease of cultivated rice (Oryza sativa). During hemibiotrophic leaf infection, the pathogen simultaneously combines biotrophic and necrotrophic growth. Here, we provide cytological and molecular evidence that, in contrast to leaf tissue infection, the fungus adopts a uniquely biotrophic infection strategy in roots for a prolonged period and spreads without causing a loss of host cell viability. Consistent with a biotrophic lifestyle, intracellularly growing hyphae of M. oryzae are surrounded by a plant-derived membrane. Global, temporal gene expression analysis used to monitor rice responses to progressive root infection revealed a rapid but transient induction of basal defense-related gene transcripts, indicating perception of the pathogen by the rice root. Early defense gene induction was followed by suppression at the onset of intracellular fungal growth, consistent with the biotrophic nature of root invasion. By contrast, during foliar infection, the vast majority of these transcripts continued to accumulate or increased in abundance. Furthermore, induction of necrotrophy-associated genes during early tissue penetration, previously observed in infected leaves, was not seen in roots. Collectively, our results not only report a global characterization of transcriptional root responses to a biotrophic fungal pathogen but also provide initial evidence for tissue-adapted fungal infection strategies.
authors.affiliation: Department of Plant Molecular Biology, University of Lausane, CH-1015 Lausane, Switzerland.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Marcel
authors.forename: Ruairidh
authors.initials: R
authors.lastname: Sawers
authors.forename: Edward
authors.initials: E
authors.lastname: Oakeley
authors.forename: Herbert
authors.initials: H
authors.lastname: Angliker
authors.forename: Uta
authors.initials: U
authors.lastname: Paszkowski
mesh_terms: D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020082:Magnaporthe / Q000472:pathogenicity*; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology*; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology*; D018749:RNA, Plant
chemical_list: D018749:RNA, Plant