Primed primary metabolism in systemic leaves: a functional systems analysis.

Area of Science:

• Plant pathology
• Plant physiology
• Biochemistry

Background:

• Plants possess defense mechanisms like systemic acquired resistance (SAR) or priming to prepare uninfected tissues against pathogens.
• While hormonal signaling and defensive compounds are well-studied, the role of primary metabolism reorganization in systemic leaves remains less explored.

Purpose of the Study:

• To investigate alterations in primary metabolism at both RNA and metabolite levels in systemic leaves of Arabidopsis thaliana following local infection with Pseudomonas syringae.

Main Methods:

• Analysis of gene expression and metabolite profiles in systemic leaves of Arabidopsis thaliana.
• Local inoculation with the bacterium Pseudomonas syringae to induce systemic acquired resistance or priming.

Main Results:

• Activation of known defense genes was observed 3-4 days post-infection.
• Significant alterations in primary metabolism were detected, including reduced nitrogen metabolism and amino acid content.
• A notable increase in organic acids, specifically fumarate and malate, was observed in systemic leaves.

Conclusions:

• The reduction in nitrogen metabolites in systemic leaves likely primes plant defense by decreasing tissue nutritional value for pathogens.
• Elevated levels of organic acids provide readily available energy and carbon building blocks for the synthesis of defense metabolites during subsequent infections.