Primed primary metabolism in systemic leaves: a functional systems analysis

Abstract

Plants evolved mechanisms to counteract bacterial infection by preparing yet uninfected systemic tissues for an enhanced defense response, so-called systemic acquired resistance or priming responses. Primed leaves express a wide range of genes that enhance the defense response once an infection takes place. While hormone-driven defense signalling and defensive metabolites have been well studied, less focus has been set on the reorganization of primary metabolism in systemic leaves. Since primary metabolism plays an essential role during defense to provide energy and chemical building blocks, we investigated changes in primary metabolism at RNA and metabolite levels in systemic leaves of Arabidopsis thaliana plants that were locally infected with Pseudomonas syringae. Known defense genes were still activated 3–4 days after infection. Also primary metabolism was significantly altered. Nitrogen (N)-metabolism and content of amino acids and other N-containing metabolites were significantly reduced, whereas the organic acids fumarate and malate were strongly increased. We suggest that reduction of N-metabolites in systemic leaves primes defense against bacterial infection by reducing the nutritional value of systemic tissue. Increased organic acids serve as quickly available metabolic resources of energy and carbon-building blocks for the production of defense metabolites during subsequent secondary infections.

Resistance against Ralstonia solanacearum in tomato depends on the methionine cycle and the γ‐aminobutyric acid metabolic pathway

“…In the process of pathogen infection a series of genes and pathways are activated, and extensive efforts have been devoted to understanding plant defense signaling pathways (Uppalapati et al ., ). Emerging evidence has shown a causal link between primary metabolism and defense responses to plant pathogens (Bolton, ; Rojas et al ., ; Lecompte et al ., ; Schwachtje et al ., ). In the present study, MTC was demonstrated to be extensively involved in R. solanacearum –tomato interactions.…”

Plant Dynamic Metabolic Response to Bacteriophage Treatment After Xanthomonas campestris pv. campestris Infection

“…They respond to "pathogen associated molecular patterns" (PAMPs) by activating a PAMPtriggered immunity (PTI) or an effector-triggered immunity (ETI) mediated by receptors able to specifically recognize pathogens (Boller and He, 2009;Navarova et al, 2012). The consequence can be the establishment of a "systemic acquired resistance" (SAR) status, which may increase resistance in the whole plant to subsequent attacks (Navarova et al, 2012;Shah et al, 2014;Schwachtje et al, 2018).…”

Volatiles of rhizobacteria Serratia and Stenotrophomonas alter growth and metabolite composition of Arabidopsis thaliana

“…Furthermore, some of the metabolic responses to St. maltophilia and S. plymuthica volatiles, namely glucose reduction, increase in malate and fumarate, the above‐mentioned decrease in putrescine and the transient reduction in glutamate, are reminiscent of Pseudomonas ‐primed primary metabolism in systemic leaves of A. thaliana (Schwachtje et al . ), but the relevance of this similarity and the role of volatiles in priming systemic responses remain to be investigated.…”