Mobilization of transposable elements (TEs) in plants has been recognized as a driving force of evolution and adaptation， in particular by providing genes with regulatory modules that impact their transcription. In this study， we employed an long-terminal repeat (LTR) promoter- fusion to show that this retrotransposon behaves like an immune-responsive gene during pathogen defense in We also showed that the endogenous copy ""， which is activated in the presence of bacterial stress， is negatively regulated by both DNA methylation and polycomb-mediated silencing， a mode of repression typically found at protein-coding and microRNA genes. Interestingly， an -derived soloLTR is located upstream of the disease resistance gene and is devoid of DNA methylation and H3K27m3 marks. Through loss-of-function experiments， we demonstrate that this soloLTR is required for the proper expression of during plant defense， thus linking the responsiveness of to biotic stress and the co-option of its LTR for plant immunity.