Multi-locus sequence typing for molecular comparison of two phytoplasmas belonging to the subgroup 16SrII-D using

It is important to distinguish closely related phytoplasms. To this purpose, sequence analysis of divergent genes has been largely used. In the present study, we analyzed the genetic diversity of alfalfa witches’ broom (AlfWB) and cucumber phyllody (CuPh) phytoplasma strains. Analysis showed that both phytoplasma strains belonged to 16SrII-D with perfect identity in their 16Sr RNA gene sequences. We designed primers and amplified SecY and rpslV- rpsC gene sequences from both phytoplasma strains. The secY and rplV-rpsC sequence identities between the two phytoplasma strains were 99.9 and 100%, respectively. We also amplified the Intron sequences of the phytoplasmas. PCR analysis revealed the presence of multiple copies of Intron fragments across the genome of both phytoplasmas. Interestingly, we found that the number and size of the amplified Intron fragments were dif-ferent between two phytoplasmas. Sequencing analysis also revealed that the amplified Introns had the highest identity with Intron sequences reported from some other phytoplasmas. The result of this study displayed the presence of diverse copies of introns in phytoplasmas belonging to 16SrII. Also we found that CuP and AlfWB phytoplasmas in Iran are closely related that may not be distinguished by conserved house-keeping genes. Based on the highly variable genomic regions (i.e Introns), however, the two phytoplasmas were distinguished. The results also revealed the potential of PCR analysis of Intron fragments to distinguish closely related pytoplasma strains of group 16SrII

کلیدواژه ها:

phytoplasma ، gene ، intron