Variability and functional role of chromosomal sequences in 16SrI-B subgroup phytoplasmas including aster yellows and related strains.
OBJECTIVE
Partial genetic characterization of several chromosomal regions on 35 16SrI-B phytoplasma strains maintained in periwinkle and collected in different geographical areas from plants of diverse species.


RESULTS
Genes coding for ribosomal protein rpL22, elongation factor EF-Tu and random cloned sequences amplified with primers AY19p/m, G35p/m and BB88F1/R1 after RFLP analyses showed a high degree of polymorphism among the strains studied. The ribosomal protein (rp) subgroups B and K, and an undescribed subgroup designated N, were identified. Amplicons obtained with primers AY19p/m and BB88F1/R1, revealed a high and a low degree of polymorphism, respectively.


CONCLUSIONS
A probable spacer role could be attributed to the AY19p/m sequence and a possible coding function to the BB88F1/R1 sequence. No relationship was found among genetic polymorphisms, identified by statistical analyses, and epidemiological or biological parameters.


CONCLUSIONS
The analyses of five different genomic sequences of the 35 strains belonging to subgroup 16SrI-B allowed a finer distinction among them, confirming that the polymorphism level of 16S rDNA is too low to be adopted as unique parameter for classification.
Botti
S
S
DiSTA, Patologia Vegetale, University of Bologna, Italy.
Bertaccini
A
A
D002876:Chromosomes, Bacterial / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D005784:Gene Amplification / Q000235:genetics; D010944:Plants / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012269:Ribosomal Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000379:methods*; D012689:Sequence Homology, Nucleic Acid; D031053:Vinca
D004269:DNA, Bacterial; D012269:Ribosomal Proteins