Agrosuppression: a bioassay for the hypersensitive response suited to high-throughput screening

Area of Science:

• Plant pathology
• Molecular biology
• Genetics

Background:

• The hypersensitive response (HR) is a crucial plant defense mechanism against pathogens.
• Existing methods for studying HR are often slow and not suitable for high-throughput screening.
• There is a need for rapid assays to screen plant and pathogen genes involved in HR.

Purpose of the Study:

• To develop and optimize a novel, high-throughput assay for studying the hypersensitive response (HR) in intact plants.
• To facilitate functional screening of plant resistance (R) genes and pathogen avirulence (Avr) genes.
• To accelerate the cloning and structure-function studies of genes involved in plant-pathogen interactions.

Main Methods:

• The agrosuppression assay utilizes Agrobacterium tumefaciens strains carrying candidate HR-inducing genes and a tumor-inducing T-DNA.
• Tumor formation is suppressed upon HR induction, providing a scorable phenotype.
• The assay was optimized in Nicotiana benthamiana using Phytophthora infestans inf1 elicitin and the Avr9/Cf-9 gene-for-gene system.

Main Results:

• Agrosuppression provides a rapid and reliable method for detecting HR induction in intact plants.
• Simple mechanical wounding of petioles enabled efficient delivery of Agrobacterium, suitable for high-throughput screening.
• The assay successfully detected HR induction mediated by known HR-eliciting genes.

Conclusions:

• Agrosuppression is a powerful new tool for high-throughput functional screening of plant and pathogen genes.
• This assay will significantly accelerate the discovery and characterization of R and Avr genes.
• The method offers a practical approach for advancing research in plant immunity and pathogen virulence.