Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2004
Publication Date: 6/1/2004
Citation: Lee, I., Bottner, K.D., Munyaneza, J.E., Campbell, W.L., Secor, G.A., Gudmestad, N.C. 2004. Closely related but distinct phytoplasmas associated with potato purple top and potato witches'-broom diseases in the U.S.. American Phytopathological Society. 94 (6) (Supplement):S58.
Technical Abstract: Phytoplasma strains belonging to the clover proliferation group (16SrVI), subgroup 16SrVI-A, have been reported to be associated with potato witches'-broom (PWB) disease in Canada and potato purple top (PPT) and similar diseases in Utah and the Columbia Basin region of Washington and Oregon. We found a potato disease similar to PWB in North Dakota and Alaska. A preliminary study indicated that this disease is also associated with 16SrVI-A phytoplasma strains. In nature, PPT and PWB phytoplasmas may represent two distinct ecological strain clusters that occur in different geographical regions and cause two different types of diseases. Based on RFLP analysis of highly conserved 16S rDNA sequences, PPT- and PWB-associated phytoplasmas could not be readily differentiated. In the present study, we employed ribosomal protein (rp) gene sequences (more variable than 16S rRNA gene) for the differentiation. RFLP analyses of rp gene sequences with restriction enzymes,AluI,MseI, Tsp509I, and TaqI differentiated PPT and PWB phytoplasma strains into four rpVI-subgroups. These results support the concept that genetic heterogeneity exists among PWB and PPT phytoplasma strains.