StAMP encoding the antigenic membrane protein of stolbur phytoplasma is useful for molecular epidemiology

The antigenic membrane protein of stolbur phytoplasma has been cloned and characterized. The expression of StAMP in Es- cherichia coli produced a 16 kDa peptide recognized by an anti-stolbur monoclonal antibody. Stamp is submitted to a positive diversifying selection pressure (Fabre et al., 2011). The genetic diversity of stamp was evaluated among a collection of stolbur phytoplasma strains representative of the tuf and secY genetic diversity of stolbur phytoplasmas in the Euro-Mediterranean basin. Most of the French, Italian and Croatian strains clustered on the same phylogenetic branch (tuf-type b cluster I). A second branch of the phylogenetic tree corresponded to strains of central and Eastern Europe (tuf-type b cluster II), while a third branch grouped strains of the east of the Mediterranean basin (Greece, Serbia, Lebanon, and Azerbaijan). Strains of the tuf-type a genotype clus- tered together in an independent monophyletic branch of the stamp phylogenetic tree. In conclusion, stamp variability seems to be correlated to geographical origin in the case of the tuf-type b strains.