A new phytoplasma associated with witches’ -broom of Cassia italica in Oman.

In several Oman locations plants of Cassia italica exhibit witches’ broom symptoms. Samples were collected from four locations, and examined for phytoplasma presence. PCR amplification using ribosomal phytoplasma primers followed by RFLP analyses indicates that the phytoplasmas present in these samples were undistinguishable from each other, but differed from those reported in the literature. RFLP and phylogenetic analysis of 16S rRNA gene plus spacer sequence confirmed that the closest phytoplasma relatives were members of the pigeon pea witches’ broom phytoplasma ribosomal group (16SrIX), sharing a 93-97% sequence similarity. Nested PCR experiments using primers amplifying the gene coding for ribosomal protein S3 provided amplification from phytoplasmas detected in C. italica, after sequencing 600 bp in this gene the higher homology showed was 78% with phytoplasmas related to ‘Candidatus Phytoplasma phoenicium’ and 77% with phytoplasmas belonging to ribosomal group 16SrIX.