UNIVERSAL AMPLIFICATION AND ANALYSIS OF PATHOGEN 16S RDNA FOR CLASSIFICATION AND IDENTIFICATION OF MYCOPLASMALIKE ORGANISMS

Regions representing about 80% of the 16S rDNA sequences of 40 mycopla smalike organism (MLO) strains from North America, Asia, and Europe we re amplified by polymerase chain reaction (PCR) using a primer pair de signed on the basis of an MLO 16S rRNA gene. This primer pair detected every MLO examined from infected periwinkle (Catharanthus roseus) and some other plants. No PCR products were obtained in samples containin g DNA extracted from healthy plants. The partial 16S rDNA sequences am plified from these various MLOs were compared through restriction frag ment length polymorphism (RFLP) analyses. Based on similarity coeffici ents derived from RFLP analyses, these 40 MLOs could be classified int o nine distinct 16S ribosomal RNA (16Sr) groups and 14 subgroups, incl uding five groups that coincide with MLO strain clusters previously de lineated on the basis of dot hybridization analysis using randomly clo ned chromosomal DNA probes. Type MLO strains designated for each group and subgroup were as follows: 16SrI-A, tomato big bud; 16SrI-B, Maryl and aster yellows; 16SrI-C, clover phyllody; 16SrI-D, paulownia witche s'-broom; 16SrI-E, blueberry stunt; 16SrII, peanut witches'-broom; 16S rIII-A, Canada peach X; 16SrIII-B, clover yellow edge; 16SrIV, palm le thal yellowing; 16SrV, elm yellows; 16SrVI, clover proliferation; 16Sr VII, ash yellows; 16SrVIII, loofah witches'-broom; and 16SrIX, pigeon pea witches-broom.