A subgroup 16SrIII-J phytoplasma associated with Aegiphila verticillata, a typical wild plant of Brazilian savanna region, exhibiting witches’ broom symptoms

Abstract

Aegiphila verticillata (parrot fruit) is a wild plant that commonly grows in Brazilian savanna fields, which are also denominated Cerrado. Trees and shrubs of this species were observed exhibiting profuse shoot proliferation that produced small leaves with mild chlorosis and flowers and fruit of reduced size which fell off prematurely. In the present study, PCR assays demonstrated the association of a phytoplasma with naturally affected plants. Identification performed with group-specific primers indicated this phytoplasma as belonging to the 16SrIII group. Molecular analysis based on virtual RFLP patterns and similarity coefficient calculations allowed to classify the phytoplasma as a representative of the 16SrIII-J subgroup. Phylogenetic analysis confirmed this result and evidenced that this phytoplasma was closely related to the reference strain for the 16SrIII-J subgroup. The disease was denominated Aegiphila witches’ broom (AegWB). In South America, representatives of the 16SrIII-J subgroup are frequently found in association with diseases of phytoplasmal etiology that occur in several wild and cultivated species. This study reveals for the first time that A. verticillata, a typical plant from the Brazilian Cerrado region, is a host of phytoplasmas, specifically of a member of the 16SrIII-J subgroup.