Newly discovered enzyme is `firing pin` for plant immunity
(PHYSorg.com Biology)

Just like humans, plants have an immune system that helps them fight off infections. Plant immunity has some important differences: they don`t make antibodies and can`t fight off the same bug more quickly months or years later. However, plant cells can identify pathogens and react to them, often by producing a burst of reactive oxygen which is toxic to bacteria or fungi. Cells around an infected site will go into programmed cell death to seal off the disease.