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Pattern-Triggered Oxidative Burst and Seedling Growth Inhibition Assays in Arabidopsis thaliana
Published on: May 21, 2019
Stem rust spores elicit rapid RPG1 phosphorylation.
Jayaveeramuthu Nirmala1, Tom Drader, Xianming Chen
1Department of Crop and Soil Sciences, Washington State University, Pullman 99164, USA.
Molecular Plant-Microbe Interactions : MPMI
|July 27, 2010
Summary
Stem rust resistance in cereals depends on RPG1 protein phosphorylation. This rapid process, triggered by avirulent stem rust spores, is crucial for activating plant defenses against this devastating pathogen.
Area of Science:
- Plant Pathology
- Molecular Biology
- Genetics
Background:
- Stem rust poses a significant threat to global cereal production.
- Durable resistance genes, like RPG1, are critical for controlling stem rust.
- Understanding the molecular mechanisms of RPG1 function is essential for developing resistant crop varieties.
Purpose of the Study:
- To investigate the role of RPG1 protein phosphorylation in conferring resistance to stem rust.
- To determine the timing and requirements for RPG1 activation upon pathogen exposure.
- To elucidate the functional domains of RPG1 involved in disease resistance.
Main Methods:
- Utilized transgenic plants expressing modified RPG1 proteins with inactive kinase domains.
- Employed protein kinase inhibitors to block RPG1 phosphorylation.
- Assessed stem rust susceptibility in response to different pathogen races and spore viability.
Main Results:
- RPG1 protein is rapidly phosphorylated within 5 minutes upon exposure to avirulent stem rust spores.
- Transgenic mutants with inactive RPG1 kinase domains are susceptible to stem rust, confirming phosphorylation is essential for resistance.
- Protein kinase inhibitors abolish RPG1 phosphorylation and lead to disease susceptibility.
- The pseudokinase pK1 domain is necessary for resistance, while the pK2 domain's kinase activity is required for phosphorylation.
Conclusions:
- Phosphorylation of the RPG1 protein, mediated by its pK2 kinase domain, is a prerequisite for resistance against avirulent stem rust races.
- The rapid phosphorylation suggests the presence of an effector within or on stem rust urediniospores.
- Live, germinating spores are required to trigger RPG1 phosphorylation and initiate the resistance response.
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