Detection, identification and molecular characterization of a phytoplasma associated with beach naupaka witches' broom

Beach naupaka (Scaevola taccada) showing witches' broom symptoms typical of phytoplasma infection were collected from a farm near Muscat (Sultanate of Oman). Polymerase chain reaction (PCR) amplification of the 16S rRNA gene and 16-23S intergenic spacer region with three pairs of phytoplasma universal primers (R16F2n/R2, AdF1/R1 and P1/P7) and transmission electron microscopy of phloem ultrathin sections, confirmed a phytoplasma infection in the symptomatic plants. RFLP analysis of the 16S rDNA sequences of the Scaevola witches' broom (ScaWB) and other phyto-plasmas reported from Oman using six restriction en-donucleases revealed that ScaWB, alfalfa witches' broom (AlfWB) and Jasmine witches' broom (JasWB) phytoplasmas shared similar RFLP patterns but different from those of the Lime witches' broom (LWB) phy-toplasma. Phylogenetic and sequence identity analyses of the 16S rRNA gene indicated that the ScaWB phyto-plasma belongs to the 16SrII group ('Candidatus Phyto-plasma aurantifolia', former Peanut witches' broom). The ScaWB phytoplasma showed 100% sequence identity with that of the Papaya yellow crinkle (PYC) and Tomato big bud (TBB) phytoplasmas. This is the first report of a phytoplasma related to 16SrII group associated with a witches' broom disease in S. taccada.