Differences between the Texas phoenix palm phytoplasma and the coconut lethal yellowing phytoplasma revealed by restriction fragement length polymorphism (RFLP) analysis of the NUSA and HFLB genes

A nested polymerase chain reaction (PCR) assay was used to amplify the nusA gene from a DNA sample extracted from a cabbage or sabal (Sabal palmetto) palm showing symptoms of Texas Phoenix decline (TPD) and from three DNA samples from coconut (Cocos nucifera) palms showing symptoms of lethal yellowing (LY). TPD is caused by a 16SrIV-D phytoplasma and LY by a 16SrIV-A strain. From the sabal DNA sample and from one coconut DNA sample two copies of the hflB gene were amplified by nested PCR. Restriction fragment length polymorphisms analysis of the PCR-amplified nusA and the hflB gene copies showed that these genes vary in the phytoplasma strains examined. Four restriction enzymes were used for the nusA gene and 16 were used for the hflB genes.