Volume 71 (1995) Issue 5 Pages 145-147
Willow witches'-broom (WWB) was found in the Edmonton area in 1994 for the first time in Canada. In this study, a simple and sensitive diagnostic method was applied and a comparative molecular genetic analysis was carried out to relate the WWB agent to known phytoplasmas. Upon application of the polymerase chain reaction using a selected pair of primers designed specifically for clover proliferation (CP) phytoplasma, the genomic DNA fragments were amplified from phytoplasma nucleic acids extracted from periwinkle, potato and alfalfa affected by CP, potato witches'-broom (PWB) and alfalfa witches'-broom (AWB), respectively. The results of restricted fragment length polymorphism analysis showed that there are no detectable molecular differences among the amplified phytoplasma DNAs originally extracted from four species of willow (Salix bebbiana Sarg., S. discolor Muhl., S. exigua Nutt, and S. petiolaris Sm.) naturally infected with WWB phytoplasma indicating the presence of only one type of phytoplasma and that WWB phytoplasma belongs to the CP group of phytoplasma organisms.