The synthetic cationic lipid diC14 activates a sector of the Arabidopsis defence network requiring endogenous signalling components

Abstract

Natural and synthetic elicitors have contributed significantly to the study of plant immunity. Pathogen-derived proteins and carbohydrates that bind to immune receptors, allow the fine dissection of certain defence pathways. Lipids of a different nature that act as defence elicitors, have also been studied, but their specific effects have been less well characterized, and their receptors have not been identified. In animal cells, nanoliposomes of the synthetic cationic lipid 3-tetradecylamino-tert-butyl-N-tetradecylpropionamidine (diC14) activate the TLR4-dependent immune cascade. Here, we have investigated whether this lipid induces Arabidopsis defence responses. At the local level, diC14 activated early and late defence gene markers (FRK1, WRKY29, ICS1 and PR1), acting in a dose-dependent manner. This lipid induced the salicylic acid (SA)-dependent, but not jasmonic acid (JA)-dependent, pathway and protected plants against Pseudomonas syringae pv. tomato (Pst), but not Botrytis cinerea. diC14 was not toxic to plant or pathogen, and potentiated pathogen-induced callose deposition. At the systemic level, diC14 induced PR1 expression and conferred resistance against Pst. diC14-induced defence responses required the signalling protein EDS1, but not NDR1. Curiously, the lipid-induced defence gene expression was lower in the fls2/efr/cerk1 triple mutant, but still unchanged in the single mutants. The amidine headgroup and chain length were important for its activity. Given the robustness of the responses triggered by diC14, its specific action on a defence pathway and the requirement for well-known defence components, this synthetic lipid is emerging as a useful tool to investigate the initial events involved in plant innate immunity.

Arabidopsis Proline Dehydrogenase Contributes to Flagellin-Mediated PAMP-Triggered Immunity by Affecting RBOHD

“…Arabidopsis Col-0 seeds were obtained from ABRC (Arabidopsis Biological Research Center, Columbus, OH, U.S.A.); prodh1-3 (GABI_308F08), prodh2-2 (GABI_328_G05), prodh2-1 (GT1788), and Ler seeds were obtained from D. Funck (University of Konstanz, Germany) and prodh1-4 (SALK_119334) from A. Savouré (Université Pierre-et-Marie-Curie, Paris); rbohD (Torres et al 2005) and fls2 (SALK_093905) were obtained from C. Zipfel (The Sainsbury Laboratory, Norwich, U.K.), MnSOD mutants (SALK_122275) from G. Pagnussat (University of Mar del Plata, Argentina) (Martin et al 2013), and AS7 lines from L. Sweetlove (Morgan et al 2008). Plant growth conditions are described elsewhere (Cambiagno et al 2015). P. syringae pv.…”

“…Bacteria scraped from fresh plates were diluted and were used to spray leaves after the addition of Silwet L-77 (0.03% vol/vol). Pathogen growth was analyzed as described (Cambiagno et al 2015), sampling by triplicate four leaf discs per genotype per time point.…”

“…sqRT-PCR and qRT-PCR were performed as described (Cambiagno et al 2015;Rizzi et al 2015). PCR conditions are indicated in Supplementary Table 1.…”

P5CDH affects the pathways contributing to Pro synthesis after ProDH activation by biotic and abiotic stress conditions

“…cDNA was synthesized from 2 μg RNA as previously described (Cambiagno et al, 2015 ). Semi-quantitative PCR was developed with primers and conditions indicated in Supplementary Table 3 .…”

Synthetic Rhamnolipid Bolaforms trigger an innate immune response in Arabidopsis thaliana

“…DPMP (2,4-dichloro-6-{( E )-[(3-methoxyphenyl)imino]methyl} phenol) triggers a robust immune response in Arabidopsis and tomato 17 . Synthetic amphiphilic molecules are also able to stimulate plant defence responses, as exemplified by short cationic lipopeptides 18 or lipid diC 14 19 .…”