title: Mycoplasma-like organisms (MLO), pathogens of the plant yellows diseases, as a model of coevolution between prokaryotes, insects and plants.
abstract: There is no satisfactory theory to explain how parasites whose effect is to kill or to weaken their hosts have been able to survive evolution. A good explanation may be found in the study of mycoplasma-like organisms (MLO). We show here the existence of natural cycles of MLO between symptomless wild plants and unaffected vectors. Such natural cycles may be the basis of a coevolutionary process by which the prokaryotes and the whole cycle have persisted to our time. Disease outbreaks occur with intrusion of a cultivated plant (direct mode) or an imported insect (indirect mode). From an evolutionary point of view, the natural cycle constitutes a protection for the host plants and natural vectors against the introduction of foreign plants or vectors as competitors in their ecological niche. A role of MLO and other parasites in evolution could be to provide stability to ecosystems, which is necessary for new characters to emerge.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004463:Ecology; D007313:Insecta / Q000382:microbiology*; D009174:Mycoplasma / Q000502:physiology*; D010935:Plant Diseases; D010944:Plants / Q000382:microbiology*