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Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):E237-E244. doi: 10.1073/pnas.1611307114. Epub 2016 Dec 27.

Two independent S-phase checkpoints regulate appressorium-mediated plant infection by the rice blast fungus Magnaporthe oryzae.

Author information

1
School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
2
School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom N.J.Talbot@exeter.ac.uk.

Abstract

To cause rice blast disease, the fungal pathogen Magnaporthe oryzae develops a specialized infection structure called an appressorium. This dome-shaped, melanin-pigmented cell generates enormous turgor and applies physical force to rupture the rice leaf cuticle using a rigid penetration peg. Appressorium-mediated infection requires septin-dependent reorientation of the F-actin cytoskeleton at the base of the infection cell, which organizes polarity determinants necessary for plant cell invasion. Here, we show that plant infection by M. oryzae requires two independent S-phase cell-cycle checkpoints. Initial formation of appressoria on the rice leaf surface requires an S-phase checkpoint that acts through the DNA damage response (DDR) pathway, involving the Cds1 kinase. By contrast, appressorium repolarization involves a novel, DDR-independent S-phase checkpoint, triggered by appressorium turgor generation and melanization. This second checkpoint specifically regulates septin-dependent, NADPH oxidase-regulated F-actin dynamics to organize the appressorium pore and facilitate entry of the fungus into host tissue.

KEYWORDS:

Pyricularia; appressorium; cell cycle; fungi; pathogen

PMID:
28028232
PMCID:
PMC5240714
DOI:
10.1073/pnas.1611307114
[Indexed for MEDLINE]
Free PMC Article

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