Lipids associated with plant-bacteria interaction identified using a metabolomics approach in an Arabidopsis thaliana model

Abstract

Background. Systemic acquired resistance (SAR) protects plants against a wide variety of pathogens. In recent decades, numerous studies have focused on the induction of SAR, but its molecular mechanisms remain largely unknown. Methods. We used a metabolomics approach based on ultra-high-performance liquid chromatographic (UPLC) and mass spectrometric (MS) techniques to identify SAR- related lipid metabolites in an Arabidopsis thaliana model. Multiple statistical analyses were used to identify the differentially regulated metabolites. Results. Numerous lipids were implicated as potential factors in both plant basal resistance and SAR; these include species of phosphatidic acid (PA), monogalactosyl- diacylglycerol (MGDG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and triacylglycerol (TG). Conclusions. Our findings indicate that lipids accumulated in both local and systemic leaves, while other lipids only accumulated in local leaves or in systemic leaves. PA (16:0_18:2), PE (34:5) and PE (16:0_18:2) had higher levels in both local leaves inoculated with Psm ES4326 or Psm avrRpm1 and systemic leaves of the plants locally infected with Psm avrRpm1 or Psm ES4326. PC (32:5) had high levels in leaves inoculated with Psm ES4326. Other differentially regulated metabolites, including PA (18:2_18:2), PA (16:0_18:3), PA (18:3_18:2), PE (16:0_18:3), PE (16:1_16:1), PE (34:4) and TGs showed higher levels in systemic leaves of the plants locally infected with Psm avrRpm1 or Psm ES4326. These findings will help direct future studies on the molecular mechanisms of SAR.