Protocol: an improved method to quantify activation of systemic acquired resistance (SAR)

Area of Science:

• Plant pathology
• Plant immunity
• Molecular plant-microbe interactions

Background:

• Plants mount systemic acquired resistance (SAR) upon pathogen detection, involving mobile signals that confer resistance to distal tissues.
• Measuring SAR activation typically involves quantifying pathogen multiplication in systemic sites, but this method suffers from experimental variation.
• High experimental variation necessitates numerous repetitions for reliable SAR assay results.

Purpose of the Study:

• To propose a modified SAR assay for improved reliability and reduced experimental variation.
• To leverage source-sink relationships (orthostichies) for more precise SAR competency assessment.
• To enhance the efficiency of SAR activation studies in the Arabidopsis-Pseudomonas syringae pathosystem.

Main Methods:

• Utilized the Arabidopsis-Pseudomonas syringae pathosystem.
• Exploited knowledge of plant source-sink relationships (orthostichies) for leaf selection.
• Implemented strict leaf selection for primary and secondary inoculation within the orthostichy of the infected leaf.

Main Results:

• Demonstrated that selecting leaves within the same orthostichy significantly improves data reliability.
• Showcased a reduction in the number of experimental repetitions required for statistically relevant SAR results.
• Validated the effectiveness of orthostichy-based leaf selection in enhancing SAR assay performance.

Conclusions:

• Direct selection of leaves exclusively within the orthostichy of the primary infected leaf is crucial for reducing experimental repetitions.
• This targeted leaf selection strategy is key to obtaining statistically relevant SAR activation results.
• The proposed modification offers a more reliable and efficient approach to studying SAR.