Chrysanthemum is a new host of a group 16SrIII phytoplasma (16SrIII-X) that induces colour-breaking in affected plants

Chrysanthemum plants showing symptoms typically induced by phytoplasmas, characterized by colour-breaking and virescence, were found with high incidences in commercial fields. Based on these symptoms, the present investigation aimed to confirm the association of phytoplasmas with affected plants. Expected genomic fragments of 1.2 Kb were generated by nested PCR revealing the occurrence of phytoplasma in all diseased plants. The presence of phytoplasma was confirmed by transmission electron microscopy that detected pleomorphic cells in the inner of phloem vessels. Nucleotide sequences from Chrysanthemum colour-breaking phytoplasma shared 99% similarity with the reference phytoplasma of the 16SrIII-X subgroup. The perfect identity was confirmed by computer-simulated RFLP analyses and similarity coefficient calculations (F equal to 1.0), as well as by the phylogenetic tree, which showed that both phytoplasmas emerge from the same branch. Our findings revealed for the first time the occurrence of a representative of the 16SrIII-X subgroup in Brazil. In addition, it also revealed that Chrysanthemum represents a novel host of a phytoplasma of the 16SrIII group in the world, since, to our knowledge, representatives of this group have not been reported inducing diseases in plants from this genus.