Variability and functional role of chromosomal sequences in 16SrI‐B subgroup phytoplasmas including aster yellows and related strains

• Published in: Journal of applied microbiology 2003-01, Vol.94 (1), p.103-110
• Main Authors: Botti, S., Bertaccini, A.
• Format: Article
• Language: English
• Subjects: Chromosomes, Bacterial - genetics; DNA, Bacterial - genetics; functional role; Gene Amplification - genetics; genetic polymorphism; PCR; Plants - microbiology; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RFLP; Ribosomal Proteins - genetics; Sequence Analysis, DNA - methods; Sequence Homology, Nucleic Acid; sequencing; Vinca
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1046/j.1365-2672.2003.01809.x

Aims: 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. Methods and 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. Significance and Impact of the Study: 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.