The article provides an update on the role of plant lectins in defense mechanisms against various organisms. Lectins are carbohydrate-binding proteins that have been isolated and characterized from many plant species. They are classified based on their ability to recognize and bind carbohydrates, but their specific functions are not fully understood. The authors define lectins as proteins with at least one noncatalytic domain that binds reversibly to a specific mono- or oligosaccharide. The article discusses the indirect and direct evidence for the defensive role of plant lectins. Indirect evidence includes the stability of lectins under unfavorable conditions, their association with vulnerable plant parts, and their ability to bind to glycoconjugates of other organisms. Direct evidence comes from studies using purified protein in artificial diets and transgenic plants. Type 2 ribosome-inactivating proteins (RIPs) are highlighted as a special class of chimeric lectins with potent cytotoxic effects on eukaryotes, fungi, and bacteria. Other lectins, such as those binding to chitin, manose, and specific animal glycoproteins, exhibit antiviral, antibacterial, antifungal, and anti-insect activities. The authors conclude that most plant lectins likely play a role in plant defense, particularly against predatory invertebrates and higher animals. The accumulation of lectins in storage organs and their storage protein-like behavior suggest that plants use them as passive defense proteins.The article provides an update on the role of plant lectins in defense mechanisms against various organisms. Lectins are carbohydrate-binding proteins that have been isolated and characterized from many plant species. They are classified based on their ability to recognize and bind carbohydrates, but their specific functions are not fully understood. The authors define lectins as proteins with at least one noncatalytic domain that binds reversibly to a specific mono- or oligosaccharide. The article discusses the indirect and direct evidence for the defensive role of plant lectins. Indirect evidence includes the stability of lectins under unfavorable conditions, their association with vulnerable plant parts, and their ability to bind to glycoconjugates of other organisms. Direct evidence comes from studies using purified protein in artificial diets and transgenic plants. Type 2 ribosome-inactivating proteins (RIPs) are highlighted as a special class of chimeric lectins with potent cytotoxic effects on eukaryotes, fungi, and bacteria. Other lectins, such as those binding to chitin, manose, and specific animal glycoproteins, exhibit antiviral, antibacterial, antifungal, and anti-insect activities. The authors conclude that most plant lectins likely play a role in plant defense, particularly against predatory invertebrates and higher animals. The accumulation of lectins in storage organs and their storage protein-like behavior suggest that plants use them as passive defense proteins.