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The rice leaf blast pathogen undergoes developmental processes typical of root-infecting fungi


Pathogens have evolved different strategies to overcome the various barriers that they encounter during infection of their hosts1. The rice blast fungus Magnaporthe grisea causes one of the most damaging diseases of cultivated rice and has emerged as a paradigm system for investigation of foliar pathogenicity. This fungus undergoes a series of well-defined developmental steps during leaf infection, including the formation of elaborate penetration structures (appressoria). This process has been studied in great detail2, and over thirty M. grisea genes that condition leaf infection have been identified3. Here we show a new facet of the M. grisea life cycle: this fungus can undergo a different (and previously uncharacterized) set of programmed developmental events that are typical of root-infecting pathogens. We also show that root colonization can lead to systemic invasion and the development of classical disease symptoms on the aerial parts of the plant. Gene-for-gene type specific disease resistance that is effective against rice blast in leaves also operates in roots. These findings have significant implications for fungal development, epidemiology, plant breeding and disease control.

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Figure 1: M. grisea undergoes developmental processes typical of root-infecting fungi.
Figure 2: Infection of roots by wild type and mutant M. grisea strains.
Figure 3: Colonization of rice roots by M. grisea is dependent on MgFOW1.
Figure 4: M. grisea can spread systemically from the roots to the aerial tissues and cause typical blast symptoms.

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We thank the M. grisea community for providing fungal strains; L. Ciuffetti for the pCT74 reporter vector, and J. Deacon and R. Gutteridge for providing the images for Fig. 1l and 1m, respectively. A.S. has been supported by a Marie Curie fellowship from the European Community and by the Gatsby Charitable Foundation.

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Correspondence to Anne E. Osbourn.

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Sesma, A., Osbourn, A. The rice leaf blast pathogen undergoes developmental processes typical of root-infecting fungi. Nature 431, 582–586 (2004).

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