Occurrence of 16SrIV Subgroup A Phytoplasmas inRoystonea regiaandAcrocomia mexicanaPalms with Lethal Yellowing-like Syndromes in Yucatán, Mexico

The lethal yellowing (LY) disease and LY-type syndromes affecting several palm species are associated with 16SrIV phytoplasmas in the Americas. In Mexico, palms of the species Roystonea regia and the native Acrocomia mexicana were found to exhibit LY-type symptoms, including leaf decay, starting with mature leaves, necrosis and atrophy of inflorescences. DNA extracts obtained from these palms could be amplified by nested-PCR using phytoplasma-universal primer pair P1/P7 followed by LY-group-specific primer pair LY16Sr/LY16Sf. Blast analysis of the sequences obtained revealed an identity of 100% for R. regia and 99.27% for A. mexicana with 16SrIV-A strain associated with LY in Florida, USA (Acc. AF498309). Computer-simulated RFLP analysis showed that the patterns for the phytoplasma DNA of the two palm species were highly similar to that for 16SrIV subgroup A strain. A neighbour-joining tree was constructed, and the sequences of the two palm species clustered in the same clade of group 16SrIV subgroup A. The results therefore support that LY-type syndromes observed in palms of R. regia and A. mexicana in the Yucatan region of Mexico are associated with 16SrIV subgroup A phytoplasmas.