such as stunting, proliferating auxiliary shoots, forming sterile
deformed flowers, virescence, and phyllody in several hundred
plant species (Lee et al. 2000). Based on phylogenetic analysis of
gene sequences (16S rRNA) phytoplasmas were recently
assigned to a provisional genus, ‘Candidatus (Ca.)
Phytoplasma’ within the class Mollicutes (IRPCM 2004). The
aster yellows (AY) phytoplasma group (16SrI) comprises AY
and numerous related phytoplasmas that are associated with
more than 100 economically important diseases worldwide,
representing the most diverse phytoplasma group (Lee et al.
2004)