Two distinct 16SrIII phytoplasma subgroups are associated with shoot proliferation in Vernonia brasiliana, a wild species inhabiting the Brazilian savanna

Abstract

Vernonia brasiliana is a wild species frequently found in Brazilian savanna areas, also known as “cerrado” areas. In pasture fields, shrubs were observed displaying typical symptoms induced by phytoplasmas, which were characterized by shoot proliferation, mild leaf chlorosis and deformed leaves. Molecular detection revealed the presence of phytoplasmas in approximately 80% of the symptomatic plants. Identification by computer-simulated RFLP allowed the classification of phytoplasma strains as representatives of ‘Candidatus Phytoplasma pruni’, taxonomic subgroups 16SrIII-B and 16SrIII-J. Moreover, phylogenetic analysis evidenced perfect agreement with virtual RFLP. Both phytoplasmas found in diseased vernonia plants have been reported in diverse commercial species cultivated in Brazil, including many vegetables and an extensive number of crops. These findings identify V. brasiliana as a new host of phytoplasmas affiliated with the subgroups 16SrIII-B and 16SrIII-J and suggest this species as a probable reservoir and possible inoculum source of phytoplasmas.