“MIDORIKO” in green algal cells: the first molecular
identification of rickettsial endosymbiotic bacteria infecting
plant cells The endosymbiosis (long-term living of organisms in
the cells of different species) is considered to make great
contributions to the establishment of mitochondoria in our
eukaryotic cells. However, no detailed information about the
endosymbiosis has been revealed. Here, we succeed a molecular
identification of bacterial endosymbionts, which were firstly
found in 1970, within the cells of volvocalean green algae
Carteria and Pleodorina. The endosymbionts "MIDORIKO" belong to
the family Rickettsiaceae (Rickettsiales, Alphaproteobacteria);
this is the first report of rickettsial endosymbionts infecting
plant cells. Bacteria belonging to this family are mainly
associated with arthropod hosts (e.g. insects or ticks), and
some of them are human-pathogenic species that cause dangerous
diseases. However, "MIDORIKO" are hosted by the plant cells and
grow without harm to their hosts. Because r