“…A congruent amount of results has already been produced in recent years, showing that phytoplasma strains that have <97?5 % similarity in their 16S rRNA gene sequence actually represent different organisms, on the basis of phylogenetic analysis based on 16S rRNA gene sequences (Namba et al, 1993b;Gundersen et al, 1994;Seemüller et al, 1994Seemüller et al, , 1998Tymon et al, 1998;Lee et al, 2000), 16S-23S rRNA gene spacer sequences , 23S rRNA gene sequences (Guo et al, 1998), ribosomal protein gene sequences (Jomantiene et al, 1998;Lee et al, 1998), transcription factor Tu gene (Schneider et al, 1997a), restriction analysis of the same genes (Schneider et al, , 1997aVibio et al, 1996;Lee et al, 1998), RFLP of total DNA with chromosomal probes (Lee & Davis, 1988;Bertaccini et al, 1990;Harrison et al, 1991Harrison et al, , 1992Hibben et al, 1991;Kuske et al, 1991;Lee et al, 1991Lee et al, , 1992aLee et al, , b, 1993aDaire et al, 1992;Davis et al, 1992a, b;Ahrens et al, 1993;Mäurer et al, 1993;Chen et al, 1994;Griffiths et al, 1994;Davis & Sinclair, 1998) and biological properties, such as insect vector specificity (Tsai, 1979;Shiomi & Sugiura, 1984;Kirkpatrick, 1992).…”