Plants’ nonspecific immune responses includes cell-surface receptors (pattern recognition proteins) which allow them to identify certain patterns characteristic for pathogens. Activated receptors trigger the production of chemical signals that may initiate both local and systemic defense responses. Sometimes when a plant is affected by infection, it triggers rapid localized programmed cell death to stop the infection further. When it comes to defense form the herbivores, plants have physical barriers (plant cell walls and their extensions), some antibiotic compounds (phytoalexins), and even enzymes that can defend them.
