Robust anti-oxidant defences in the rice blast fungus Magnaporthe oryzae confer tolerance to the host oxidative burst
Article first published online: 3 OCT 2013
© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust
Volume 201, Issue 2, pages 556–573, January 2014
How to Cite
Samalova, M., Meyer, A. J., Gurr, S. J. and Fricker, M. D. (2014), Robust anti-oxidant defences in the rice blast fungus Magnaporthe oryzae confer tolerance to the host oxidative burst. New Phytologist, 201: 556–573. doi: 10.1111/nph.12530
- Issue published online: 18 DEC 2013
- Article first published online: 3 OCT 2013
- Manuscript Accepted: 20 AUG 2013
- Manuscript Received: 7 JUN 2013
- Biotechnology and Biological Sciences Research Council. Grant Number: BB/G00207X/1
- confocal redox imaging;
- Magnaporthe oryzae ;
- mitochondrial activity;
- reactive oxygen species (ROS);
- rice blast pathogen response
- Plants respond to pathogen attack via a rapid burst of reactive oxygen species (ROS). However, ROS are also produced by fungal metabolism and are required for the development of infection structures in Magnaporthe oryzae.
- To obtain a better understanding of redox regulation in M. oryzae, we measured the amount and redox potential of glutathione (EGSH), as the major cytoplasmic anti-oxidant, the rates of ROS production, and mitochondrial activity using multi-channel four-dimensional (x,y,z,t) confocal imaging of Grx1-roGFP2 and fluorescent reporters during spore germination, appressorium formation and infection.
- High levels of mitochondrial activity and ROS were localized to the growing germ tube and appressorium, but EGSH was highly reduced and tightly regulated during development. Furthermore, germlings were extremely resistant to external H2O2 exposure ex planta. EGSH remained highly reduced during successful infection of the susceptible rice cultivar CO39. By contrast, there was a dramatic reduction in the infection of resistant (IR68) rice, but the sparse hyphae that did form also maintained a similar reduced EGSH.
- We conclude that M. oryzae has a robust anti-oxidant defence system and maintains tight control of EGSH despite substantial oxidative challenge. Furthermore, the magnitude of the host oxidative burst alone does not stress the pathogen sufficiently to prevent infection in this pathosystem.