The article discusses the significance of inducible defense-related proteins in plants, which are activated upon infection by various pathogens or stress conditions. These proteins, classified into 17 families of pathogenesis-related proteins (PRs), are induced by signaling compounds like salicylic acid, jasmonic acid, and ethylene. They possess antimicrobial activities through hydrolytic activities on cell walls, contact toxicity, and potential involvement in defense signaling. However, their effectiveness in transgenic plants is limited, depending on the protein, plant species, and pathogen involved. The article highlights that many PRs are regulated developmentally and serve different functions in specific organs or tissues. Some defense-related proteins are induced during senescence, wounding, or cold stress, and some have antifreeze activity. Many are constitutively present in floral tissues and can provoke allergies in humans. The evolutionary conservation of these proteins suggests they serve essential functions in plant life, whether in defense or other contexts. The article also explores the relationship between PR-1-type proteins and plant defense, noting their conserved structure and diverse biological activities. It discusses the activities and biological significance of other inducible defense-related proteins, such as β-1,3-glucanases, chitinases, and thaumatin-like proteins, and their effectiveness in enhancing resistance against specific pathogens. Finally, it examines the signaling pathways involved in the induction of defense-related proteins, including the role of salicylic acid and the mobile signal in systemic acquired resistance (SAR).The article discusses the significance of inducible defense-related proteins in plants, which are activated upon infection by various pathogens or stress conditions. These proteins, classified into 17 families of pathogenesis-related proteins (PRs), are induced by signaling compounds like salicylic acid, jasmonic acid, and ethylene. They possess antimicrobial activities through hydrolytic activities on cell walls, contact toxicity, and potential involvement in defense signaling. However, their effectiveness in transgenic plants is limited, depending on the protein, plant species, and pathogen involved. The article highlights that many PRs are regulated developmentally and serve different functions in specific organs or tissues. Some defense-related proteins are induced during senescence, wounding, or cold stress, and some have antifreeze activity. Many are constitutively present in floral tissues and can provoke allergies in humans. The evolutionary conservation of these proteins suggests they serve essential functions in plant life, whether in defense or other contexts. The article also explores the relationship between PR-1-type proteins and plant defense, noting their conserved structure and diverse biological activities. It discusses the activities and biological significance of other inducible defense-related proteins, such as β-1,3-glucanases, chitinases, and thaumatin-like proteins, and their effectiveness in enhancing resistance against specific pathogens. Finally, it examines the signaling pathways involved in the induction of defense-related proteins, including the role of salicylic acid and the mobile signal in systemic acquired resistance (SAR).