GroEL gene characterization of “bois noir” phytoplasma from Serbia, Bulgaria and Italy

Stolbur phytoplasma belongs to ribosomal subgroup 16SrXII-A and is associated with ‘bois noir’ disease of grapevine. Sequence and RFLP analyses of 16S rDNA of stolbur phytoplasma show small or no variability among the strains that originate from different parts of the world (Garnier, 2000). However there are reports of molecular variability in other genes such as tuf, vmp1, stamp and secY genes (Pacifico et al., 2007; Cimerman et al., 2009; Fabre et al., 2011). So far, tuf gene is the only gene for which it has been shown that is related to specific herbaceous host and a vector population (Langer and Maixner, 2004). Encoded gene for large subunit of molecular chaperonin (groEL gene) has already been used as molecular marker for better identification of some bacterial species such as Salmonella and Staphylococcus, or for characterization of different serotypes of Streptococcus suis (Goh, 1996; Satheesh, 2002; Brousseau i sar., 2001). In previous reports, RFLP analysis of groEL gene was shown to be a useful tool in characterization of aster yellows strains and stolbur phytoplasma from different plant hosts (Mitrović et al., 2011; Mitrović and Duduk 2012). Therefore, variability of groEL gene of previously identified BN strains from Serbia, Bulgaria and Italy was investigated.