Assay for pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) in plants

Area of Science:

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

Background:

• Plants utilize pattern recognition receptors (PRRs) to detect conserved microbial features, known as pathogen-associated molecular patterns (PAMPs).
• This recognition initiates PAMP-triggered immunity (PTI), a crucial defense mechanism preventing pathogen colonization.
• Pathogens can suppress PTI using effectors, while plants may employ effector-triggered immunity (ETI) to counter these suppressors.

Purpose of the Study:

• To develop and standardize a novel cell death-based assay for evaluating PAMP-triggered immunity (PTI) in plants.
• To assess the efficacy of PTI in preventing pathogen-induced cell death using a standardized experimental setup.
• To validate the assay's utility in model systems like Nicotiana benthamiana for studying plant-pathogen interactions.

Main Methods:

• A cell death assay was adapted and standardized in Nicotiana benthamiana, a model for plant-pathogen studies.
• PTI was induced by infiltrating a non-pathogenic bacterial strain into leaves.
• Seven hours post-induction, a second challenge inoculation (pathogenic or ETI-activating strain) was applied to an overlapping zone to assess PTI's protective effect.

Main Results:

• PTI induction successfully delayed or prevented cell death caused by the subsequent challenge inoculation in control plants.
• The appearance of cell death in the overlapping zone indicated a breakdown of PTI.
• Plants with silenced FLS2, a key component of PTI, showed compromised ability to resist challenge inoculations, validating the assay's sensitivity.

Conclusions:

• The developed cell death assay effectively measures the functional status of PAMP-triggered immunity (PTI).
• This assay provides a valuable tool for dissecting the mechanisms of PTI and its suppression by pathogens.
• The findings highlight the importance of the FLS2 pathway in PTI and offer a standardized method for future research in plant immunity.