Molecular survey of the Texas Phoenix decline phytoplasma population in Florida, USA

A nested polymerase chain reaction (PCR) assay was used to amplify 16S-23S intergenic spacer (IGS) region from DNA samples individually extracted from 25 Sabal palmetto (cabbage palms) showing symptoms of Texas Phoenix decline (TPD) in West Central Florida. The IGS region was also amplified from DNA from other palm species showing symptoms of TPD and lethal yellowing (LY). A subset of the aforementioned phytoplasma DNA samples (Sabal and other palm species) together with additional samples from various hosts collected from different geographical localities were further studied to compare the collected phytoplasma strains using sequence analysis of the glycoprotease (gcp) genes. Restriction fragment length polymorphisms (RFLP) analysis of the PCR-amplified 16S-23S IGS region and the gcp gene using a three restriction enzymes showed that the population of the phytoplasmas infecting S. palmetto in West Central Florida is probably homogenous. The S. palmetto phytoplasma also appeared similar to all the 16SrIV-D phytoplasmas infecting other palm species and different from all phytoplasmas belonging to the 16SrIV-A subgroup. We recommend more work using genes or genomic regions other than the 16S-23S IGS region and the gcp gene to be done.