THE RDNA INTERNAL TRANSCRIBED SPACER REGION AS A TAXONOMIC MARKER FORNEMATODES

The ITS region from a wide taxonomic range of nematodes, including sec ernentean and adenophorean taxa, and free-living, entomopathogenic, an d plant-parasitic species, was evaluated as a taxonomic marker. Size o f the amplified product aided in the initial determination of group me mbership, and also suggested groups that may require taxonomic reevalu ation. Congeneric species often displayed identically sized ITS region s, but genera such as Pratylenchus and Tylenchorynchus had species wit h large differences in size. ITS heterogeneity in individuals and popu lations was identified in several nematode taxa. PCR-RFLP of ITS1 is a dvocated as a method of taxonomic analysis in genera such as Helicotyl enchus that contain numerous species with few diagnostic morphological characteristics.