DETECTION IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF A PHYTOPLASMA ASSOCIATED WITH BEACH NAUPAKA WITCHES’ BROOM
A.D. Al-Zadjali, A.M. Al-Sadi, M.L. Deadman, S. Okuda, T. Natsuki, T.S. Al-Zadjali
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 phytoplasmas reported from Oman using six restriction endonucleases 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) phytoplasma. Phylogenetic and sequence identity analyses of the 16S rRNA gene indicated that the ScaWB phytoplasma belongs to the 16SrII group (‘Candidatus Phytoplasma 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.