Structural and evolutionary analysis of the ribosomal genes of the parasitic nematode Meloidogyne artiellia suggests its ancient origin

Root-knot nematodes belonging to the genus Meloidogyne constitute one of the major groups of plant pathogens of outstanding economic importance. They are facultative or obligate parthenogens, so a single individual can establish a population, a useful attribute in species that exploits disturbed ecosystems such as the agro-ecosystems. Molecular studies of root knot nematode ribosomal genes are undertaken both to elucidate their phylogenetic relationships and to develop DNA-based methods for their identification. Within the order Tylenchida, Meloidogyne artiellia 5S rRNA has a different location, with respect to other Meloidogyne species, but similar to that observed in the distantly related Caenorhabditis elegans, order Rhabditida. Moreover the availability of the complete sequence of the M. artiellia repeated ribosomal unit, allowed us to address phylogenetic relationships within the genus Meloidogyne. M. artiellia displays several characteristics, presumably present in the common ancestor, whose traces are still present in members of the different order Rhabditida, such as C. elegans, in spite of the extremely fast evolution of nematodes.