Characterization and vector identification of phytoplasmas associated with cucumber and squash phyllody in Iran

Phytoplasmas associated with cucumber phyllody (CuP) and squash phyllody (SqP) in Yazd province of Iran were characterized by molecular analyses and biological studies. Orosius albicinctus leafhoppers testing positive for phytoplasma presence by polymerase chain reaction (PCR) successfully transmitted CuP and SqP phytoplasmas to healthy cucumber and squash plants. The phytoplasmas were also transmitted by O. albicinctus from cucumber and squash to periwinkle, alfalfa, cucumber, carrot, sesame, sunflower, pot marigold, eggplant, squash, tomato and parsley. Both phytoplasmas induced similar symptoms in the post-inoculated plants. Restriction fragment length polymorphism (RFLP) analysis of the 16S rDNA nested PCR products identified the CuP, SqP and O. albicinctus phytoplasmas as members of the 16SrII group. Sequence identity and phylogenetic analysis confirmed the placement of these phytoplasmas in the same clade of other phytoplasmas belonging to 16SrII group. Virtual RFLP analyses on 16S rDNA sequences allowed the affiliation of SqP phytoplasma to subgroup 16SrII-D, while the CuP phytoplasma was identified as representative of a new subgroup 16SrII-M. This is the first report on molecular characterization of the CuP and SqP phyllody phytoplasmas, including subgroup affiliation, identification of their leafhopper vector and determination of their plant host range in Iran.