Why do GO terms use the word “symbiont” instead of “pathogen”?
Pathogenesis often includes the proliferation or reproduction of a microbe in a plant or animal host. The extent to which such proliferation and accompanying microbial processes are detrimental (and thus pathogenic) to the host depends on many factors, including the biotic or abiotic environment and the physiology of the host, especially the strength of the defense response. The identical microbe or host process can be beneficial or detrimental depending on the context. For example, necrotrophy associated with the plant hypersensitive response to biotrophic and hemibiotrophic pathogens, while involving some host cell death, can be considered beneficial to the host. The pathogen is curtailed at the point of infection and denied access to any living tissue at the necrotic front. On the other hand, for necrotrophs that live on exudates from dead tissues, the identical type of cell killing is beneficial to the pathogen. These examples illustrate the difficulties confronted by PAMGO and the
