BIOLOGICAL AND MOLECULAR CHARACTERIZATION OF A PHYTOPLASMA ASSOCIATED WITH GREENHOUSE CUCUMBER PHYLLODY IN FARS PROVINCE*

Greenhouse cucumber phyllody (GCP) is an economically important disease in Iran. Agent of GCP from Larestan (Fars province) was transmitted from greenhouse cucumber to periwinkle and eggplant using dodder inoculation. Agents of phyllody of greenhouse cucumber, petunia, rapeseed, and  phytoplasmas associated with Macrosteles levis and Psammottetix striatus leafhoppers, all maintained and propagated  in periwinkle, were graft transmitted to young periwinkle plants of the same age for symptomatological  differentiation. On the basis of disease symptoms in periwinkle, GCP phytoplasma was not differentiated from Petunia phyllody (PP) phytoplasma but was differentiable from the other phytoplasma strains used in this study. Restriction fragment length polymorphism (RFLP) analysis of P1/P7 primed PCR products showed that GCP phytoplasma is not differentiable from PP phytoplasma but different from phytoplasmas associated with rapeseed phyllody and those found in the leafhoppers. Sequence homology and phylogenetic analyses of 1800 bp of  rRNA operon identified GCP phytoplasma as a member of  peanut witches' broom phytoplasma group(16SrII). On the basis of the same molecular analyses GCP phytoplasma was differentiable from the Fars and Yazd alfalfa witches' broom phytoplasmas and the phytoplasma associated with lime witches' broom disease, the three economically important phytoplasma diseases in Iran , all  from peanut witches' broom phytoplasma group.  Greenhouse cucumber is reported for the first time as a new natural host for the peanut witches' broom phytoplasma group.