Arachidonic Acid: An Evolutionarily Conserved Signaling Molecule Modulates Plant Stress Signaling Networks  

Abstract

Fatty acid structure affects cellular activities through changes in membrane lipid composition and the generation of a diversity of bioactive derivatives. Eicosapolyenoic acids are released into plants upon infection by oomycete pathogens, suggesting they may elicit plant defenses. We exploited transgenic Arabidopsis thaliana plants (designated EP) producing eicosadienoic, eicosatrienoic, and arachidonic acid (AA), aimed at mimicking pathogen release of these compounds. We also examined their effect on biotic stress resistance by challenging EP plants with fungal, oomycete, and bacterial pathogens and an insect pest. EP plants exhibited enhanced resistance to all biotic challenges, except they were more susceptible to bacteria than the wild type. Levels of jasmonic acid (JA) were elevated and levels of salicylic acid (SA) were reduced in EP plants. Altered expression of JA and SA pathway genes in EP plants shows that eicosapolyenoic acids effectively modulate stress-responsive transcriptional networks. Exogenous application of various fatty acids to wild-type and JA-deficient mutants confirmed AA as the signaling molecule. Moreover, AA treatment elicited heightened expression of general stress-responsive genes. Importantly, tomato (Solanum lycopersicum) leaves treated with AA exhibited reduced susceptibility to Botrytis cinerea infection, confirming AA signaling in other plants. These studies support the role of AA, an ancient metazoan signaling molecule, in eliciting plant stress and defense signaling networks.

Eicosapolyenoic acids

“…AA 2 we demonstrate that (1) AA reciprocally impacts salicylate and jasmonate signaling networks in a manner consistent with the observed outcomes to various biotic challengers and associated gene expression, (2) AA's effects in Arabidopsis are dependent upon jasmonic acid and (3) direct application of AA to Arabidopsis or tomato leaves results in a generalized rapid stress response, manifested as enhanced tolerance to Botrytis infection. These responses, triggered by AA, but not by less-unsaturated eicosenoic acids or fatty acids common to the plant, support the notion that as in animals AA potentiates transcriptional regulation of a selected group of stress responsive genes in plants with the ultimate outcome of enhanced tolerance of plants to a range of biotic stresses.…”

Lipids as Markers of Induced Resistance in Wheat: A Biochemical and Molecular Approach

“…C20:2 content seemed to be affected by fungal infection of the plant to a greater extent than by any of the resistance inducing treatments, since similar quantities were found in watercontrol (i) plants as well as in resistance inducers-treated plants. The link between C20:2 and infection was also reported in [82].Transgenic A. thaliana plants producing C20:2 exhibited enhanced resistance to the aphid Myzus persicae, the fungal pathogen Botrytis cinerea and to the oomycete pathogen Phytophtora capsici.…”

Metabolomics of Disease Resistance in Crops

“…As examples, the induction of leukotrienes and thromboxanes from arachidonic acid occurs in acute and chronic inflammatory processes (Hammond and O'Donnell, 2012). These responses are also downregulated after application of non-steroidal anti-inflammatory drugs such as acetyl salicylic acid or ibuprofen (Savchenko et al, 2010). Unlike animal systems, In plant-pathogen interactions, much attention is paid to soluble semipolar metabolites as most phytoalexins and phytoanticipins fall within this category.…”