Presence of a Phytoplasma Associated with Witches’-Broom Disease in Ugni molinae Turcz. and Gaultheria phillyreifolia (Pers.) Sleumer Determined by DAPI, PCR, and DNA Sequencing

Abstract

Murta (Ugni molinae Turcz.) and common chaura (Gaultheria phillyreifolia (Pers.) Sleumer) are native species of Chile. Plants of both species have shown over-branching like witches' broom. The causal agents of these symptoms in many plants are phytoplasma. To verify the presence of these microorganisms, DAPI (4', 6-diamidino-2- phenylindole) staining analysis and polymerase chain reaction (PCR) were performed in symptomatic and asymptomatic plants. Positive PCR samples were sequenced to identify the pathogens involved. In individuals of both species with witches' broom symptoms, DAPI staining showed fluorescent bodies in the phloem tissues, but not in asymptomatic plants. Verification by nested-PCR, phytoplasmatic DNA was amplified from diseased murta and chaura, but not in apparently healthy plants. Sequencing of amplified products allowed locating phytoplasma within the ash yellows group (16SrVII) and related to Candidatus phytoplasma fraxini. This is the first report of phytoplasma in Chilean native species. Considering the diversity of plant species infected by the ash yellows group suggests that G. phillyreifolia and U. molinae could be a phytoplasma reservoir for other economically important agricultural crops.