Tomato big bud associated with a phytoplasma belonging to group 16Sr III in Brazil

Abstract

Tomato plants displaying foliar chlorosis, shoot proliferation, calyx deformation and reduced leaves, flowers and fruits all symptoms of tomato big bud, were found in a culture at Bragança Paulista region, State of São Paulo, Brazil. Samples were collected and analyzed by electron microscopy, PCR and RFLP to detect and identify the possible phytoplasma associated with diseased plants. Pleomorphic and round corpuscles were observed in the phloem vessels of diseased plants; the presence of phytoplasma was confirmed by PCR using universal primer pairs. PCR assays primed by group-specific primer pairs enabled the identification of the detected phytoplasma as a member of the 16SrIII group. Molecular identification by RFLP using various endonucleases confirmed the classification of this phytoplasma as a representative of the 16SrIII group. Phytoplasmas that are associated with big bud have been classified in different groups. The big bud phytoplasma identified in Brazil belongs to the same group of phytoplasmas associated with tomato big bud in Italy, but it is different from those found in other areas of the world.