Hypersensitive response

The hypersensitive response (HR) is a mechanism, used by plants, to prevent the spread of infection by microbial pathogens. The HR is characterized by the rapid death of cells in the local region surrounding an infection. The HR serves to restrict the growth and spread of pathogens to other parts of the plant. The HR is analogous to the innate immune system found in animals, and commonly precedes a slower systemic (whole plant) response, which ultimately leads to systemic acquired resistance (SAR).