Elicitation de la résistance systémique induite chez les plantes par les PGPR

Abstract

Induced Systemic Resistance (ISR) is a plant defense mechanism activated by beneficial microorganisms, particularly Plant Growth-Promoting Rhizobacteria (PGPR), which trigger immunity without causing disease. This thesis explores various types of bacterial elicitors, such as Microbe-Associated Molecular Patterns (MAMPs) like flagellin, lipopolysaccharides, and peptidoglycan, as well as cyclic lipopeptides, hydrogen cyanide, volatile organic compounds, siderophores, and certain antibiotics. These molecules are perceived by specific receptors on the surface of plant cells, such as Receptor-Like Kinases (RLKs), Flagellin-Sensing 2 (FLS2), Wall-Associated Kinase (WAK), and PEPR. Their recognition triggers a signaling cascade involving the jasmonic acid, ethylene, and salicylic acid hormonal pathways, along with transcriptional regulation by key factors such as NPR1 and PDF1.2. The activation of these pathways leads to systemic defense responses including reactive oxygen species production, hypersensitive response, programmed cell death, stimulation of the lipoxygenase pathway, and reinforcement of structural barriers, thereby enhancing the plant’s resistance to future pathogen attacks.