INTERSPECIFIC RDNA RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM IN GLOBODERA SPECIES, PARASITES OF SOLANACEOUS PLANTS

The status of the Globodera species that are parasites of Solanaceous is still unclear due to low morphological polymorphism. Two 21-mers ol igonucleotide primers were used to amplify the Internal Transcribed Sp acer (ITS). The amplified product was aproximately 1.2 Kb in the 26 Gl obodera populations examined. Thirty-one restriction enzymes were test ed, of which twelve produced some fragment length polymorphism. These RFLP's were recorded, generic distances were calculated, and a dendrog ram was generated. Intraspecific polymorphism was low, but interspecif ic polymorphism allowed for easy species differenciation. The four rev ealed clusters corresponded to G. tabacum group, G. rostochiensis, G. pallida, and G. ''mexicana''. These results confer a species status to G. ''mexicana'' whose genetic identity was unclear and are discussed with regard to previous hybridisation and to 2D electrophoresis, Furth er sequencing of the ITS was done to search for intraspecific polymorp hism. These three G. rostochiensis sequences were compared to previous ly published sequences for five Heterodera populations and for Caenorh abditis elegans.