Mycoplasma-like organisms (MLO), pathogens of the plant yellows diseases, as a model of coevolution between prokaryotes, insects and plants.
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.
D000818:Animals; D005075:Biological Evolution; D004463:Ecology; D007313:Insecta / Q000382:microbiology*; D009174:Mycoplasma / Q000502:physiology*; D010935:Plant Diseases; D010944:Plants / Q000382:microbiology*