Bitter gourd little leaf disease associated to 'Candidatus Phytoplasma asteris'

Abstract

Little leaf disease symptoms including dwarfed, thickened and puckered leaves and shortened internodes of bitter gourd (Momordica charantia L.) plants were observed in Meiktila, Myanmar 2012. The causal agent was detected by polymerase chain reaction using universal phytoplasma primers, and classified by sequencing of 16S rRNA gene, ribosomal protein (rp) gene and protein translocase subunit (secY) gene and RFLP analysis. The expected target phytoplasma DNA fragment of 1.8 kbp was amplified from the bitter gourd little leaf (BitLL) diseased samples. The 16S rRNA gene sequence analysis of BitLL phytoplasma showed 99.7% to 99.9% identity with members of 'Candidatus Phytoplasma asteris' associated with sesame phyllody (SP), periwinkle phyllody (PeP) and periwinkle little leaf (PeLL) diseases in Myanmar. Moreover, rp and secY gene sequences of the BitLL isolate were 99.7% to 100%, and 99.9% to 100% identity among the SP, PeP and PeLL phytoplasma. However, putative restriction analysis revealed that the BitLL isolate missed one Mse I site on rp gene sequence while other isolates had the same restriction sites. Phylogenetic analysis of the three genes confirmed that the phytoplasma belongs to the 'Ca. P. asteris'. This is the first report of 'Ca. P. asteris' infecting a member of the family Cucurbitaceae in Myanmar.