Molecular characterization of white leaf phytoplasma associated with the graminae in Myanmar

Typical white leaf disease symptoms were observed on Bermuda grass (Cynodon dactylon) in Magway and Nyungoo, and goosegrass (Eleusine indica) in Kyaukpadaung of Myanmar, 2011. Phytoplasma associations with these grasses were determined by polymerase chain reaction analysis with amplified DNA fragment of 1.8 kbp including nearly full-length of 16S rRNA, 16S-23S spacer region and partial of 23S rRNA gene. The 16S rRNA gene sequence analysis resulted that two Bermuda grass white leaf (BGWL) isolates had the highest similarity (99%) with members of 'Candidatus Phytoplasma cynodontis'. The goosegrass white leaf (GGWL) phytoplasma showed <98.8% identity with 16S rRNA gene sequences of 'Ca. P. cynodontis' and sugarcane white leaf phytoplasma (SCWL, AB646271), and shared 99.5% similarity with that of sorghum grassy shoot (SGS, AF509324). Percent homology of 16S-23S spacer region sequences showed that the GGWL isolate was closet (97% identity) to SCWL. Putative restriction site analysis of 16S rRNA gene sequence including spacer region and partial of 23S rRNA gene revealed that the GGWL isolate was distinguished from the BGWL isolate. The phylogenetic analysis proved that the GGWL isolate diverged from the sugarcane white leaf phytoplasmas and closely related with SGS phytoplasma. In addition, the GGWL phytoplasma was distantly related with 'Ca. P. cynodontis' and SCWL group. This is the first report on the presence of Bermuda grass white leaf and goose grass white leaf phytoplasmas in Myanmar.