RNA-Seq of Arabidopsis Col-0 and sid2 seedlings treated with L-Glu and urea

Plant resistance inducers (PRIs) are compounds that protect crops from diseases by activating plant immunity. The exogenous treatment with glutamate (Glu), an important amino acid for living organisms, was shown to induce resistance against fungal pathogen in rice and tomato. To understand the molecular mechanism of Glu-induced immunity, we developed a model system using Arabidopsis thaliana. Here, we found that exogenous treatment with Glu to Arabidopsis enhances resistance against Pseudomonas syringae pv. tomato DC3000 and Colletotrichum higginsianum. Consistently, transcriptome analyses of Arabidopsis seedlings treated with Glu showed that Glu significantly induces the expression of wound, defense, and stress related genes. Interestingly, Glu activates the expression of pathogen or damage associated molecular patterns (PAMP or DAMP)–inducible genes at much later time points than PAMP/DAMPs normally do. Moreover, expression of Glu-inducible genes does not require known components of PAMP receptor complex, glutamate receptors, salicylic acid-biosynthesis enzyme, or glutamate decarboxylase. In addition, Glu also enhances PAMP-inducible immune responses, such as production of reactive oxygen species and mitogen-activated protein kinase activation. These results show that Glu activates PAMP/DAMP-triggered immunity signaling pathway in a novel manner. Overall design: Examination of L-Glu-inducible genes in Arabidopsis Col-0 and sid2 seedlings after 48h treatment.