Pathogenic microorganisms are one of the main risks faced by agriculture in the 21st century, since they pose a limitation to agricultural production and the ability to support a continuously growing population. Likewise, traditional protection treatments against pathogens are currently the subject of growing social concern due to their environmental impact, making a priority the design of new, more sustainable control strategies. For this purpose, the identification and characterization of defense mechanisms against pathogens with potential application to crop protection is essential. This project is based on data obtained by the research group, showing a remarkable degree of transcriptional overlap between defense responses against P. syringae and some genes regulated by gene silencing, such as response genes to the phytohormone jasmonic acid (JA) involved in defense and other relevant aspects of plant physiology. Our results support the working hypothesis of the proposal: that the role of the response to JA in the interaction with P. syringae, and possibly other biotrophic pathogens such as geminiviruses, is directly or indirectly regulated by miRNAs. The project aims to characterize the molecular mechanism involved in regulation mediated by miRNAs during the defense response against P. syringae and geminiviruses, and the impact of said regulation on the ability of the plant to defend itself. We have set two key objectives: (i) identify and validate the miRNAs, and their corresponding host targets, involved in the regulation of the defense against P. syringae mediated by jasmonates, and (ii) characterize the role of miR319 in the regulation of the jasmonate-mediated defense against P. syringae and geminiviruses.