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Research Paper

Quantitative proteomics identifies oxidant-induced, AtMPK6-dependent changes in Arabidopsis thaliana protein profiles

Godfrey P. Miles, Marcus A. Samuel, Jeffrey A. Ranish, Sam M. Donohoe, Gina M. Sperrazzo and Brian E. Ellis

In Arabidopsis thaliana, oxidant-induced signalling has been shown to utilize the mitogen-activated protein kinase (MAPK), AtMPK6. To identify proteins whose accumulation is altered by ozone in a MPK6-dependent manner we employed isotope-coded affinity tagging (ICAT) technology to investigate the impact of AtMPK6-suppression on the protein profiles in Arabidopsis both before (air control) and during continuous ozone (O3) fumigation (500 nL L^-1 for 8 h). Among the 150 proteins positively identified and quantified in the O₃-treated plants, we identified thirteen proteins whose abundance was greater in the AtMPK6-suppressed genotype than in wild-type (WT). These include the antioxidant proteins, monodehydroascorbate reductase, peroxiredoxin Q, and glutathione reductase. A further eighteen proteins were identified whose abundance was lower in the ozone-treated AtMPK6-suppressed line relative to ozone-exposed WT plants. These predominantly comprised proteins involved in carbohydrate-, energy-, and amino acid metabolism, and tetrapyrrole biosynthesis.  In control plants, five proteins increased, and nine proteins decreased in abundance in the AtMPK6-suppressed genotype compared to that of the WT, reflecting changes in the protein composition of plants that have AtMPK6 constitutively suppressed. Since a number of these proteins are part of the redox response pathway, and loss of AtMPK6 renders Arabidopsis more susceptible to oxidative stress, we propose that AtMPK6 plays a key role in the plant’s overall ability to manage oxidative stress.

Authors

Godfrey P. Miles Corresponding author: godfrey.miles@ars.usda.gov

Michael Smith Laboratories; University of British Columbia; Vancouver, BC CA

Marcus A. Samuel

Department of Biological Sciences; University of Calgary; Calgary, AB CA

Jeffrey A. Ranish

Institute for Systems Biology; Seattle, Washington USA

Sam M. Donohoe

Institute for Systems Biology; Seattle, Washington USA

Gina M. Sperrazzo

Institute for Systems Biology; Seattle, Washington USA

Brian E. Ellis Corresponding author: bee@interchange.ubc.ca

Michael Smith Laboratories; University of British Columbia; Vancouver, BC CA