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Systems Biology Project
Title Investigating the biology of appressorium-mediated plant infection by the rice blast fungus magnaporthe grisea
Principal Investigator Professor Nick Talbot
Summary The project will explore the biology of appressorium-mediated plant infection by Magnaporthe grisea, the rice blast fungus. We have discovered that two NADPH oxidase-encoding (NOX1 and NOX2) genes are necessary for rice blast disease due to an effect on the biology of appressoria, the specialised cells used by the fungus to bring about plant infection. An oxidative burst occurs during appressorium maturation and reactive oxygen species (ROS) generation requires NADPH oxidase activity.
We will characterise the Nox3 NADPH oxidase and examine the regulation of Nox1, Nox2 and Nox3 activity by Rac1, noxR and the Ca2+ signalling pathway. We will use cell wall proteome analysis to identify major changes associated with the onset of the oxidative burst during appressorium maturation. The physical interactions between p67phox, Rac1 and the Nox family, their cellular localisation and the role of Ca2+ in regulation of Nox3 will be investigated. We will then explore the role of trehalose-6-phosphate synthase (Tps1), which is a central regulator of carbon and nitrogen metabolite repression in M. grisea and is essential for pathogenesis. The role of Tps1 in regulating nitrogen source utilization by interaction with the NMR repressor gene family will be explored using gene functional analysis and protein- protein interaction studies.
Reporter gene fusions will be used to investigate the temporal regulation of sub-cellular distribution of the Nmr repressors, the Nut1 transcription factor and Tps1. The effect of Tps1 on cytoskeletal organisation during appressorium morphogenesis will also be explored. The effect of Tps1 on cellular NADPH levels and the potential role of Tps1 as a direct sensor of cellular NADPH will be investigated by mutagenesis, direct NADPH-binding assays and metabolite analysis during infection-related development by M. grisea. The effect of Tps1 on the regulation of ROS generation and appressorium function will be determined.
Funding body BBSRC
Timescale 2009 to 2012
