ความหลากหลายทางพันธุกรรมของเชื้อไฟโตพลาสมาที่ก่อโรคในอ้อย และหญ้าบางชนิดของประเทศไทย จากลำดับนิวคลีโอไทด์บริเวณ 16S-23S rRNA intergenic spacer region | Genetic diversity of phytoplasma associated with diseases of sugarcane and some grasses in Thailand based on sequencing analysis of the 16S-23S rRNA intergenic spacer region

The phylogenetic analysis of phytoplasmas focused on the nucleotide sequences of the intergenic 16s-23s rRNA spacer region that primers enable the amplification of a 210 bp fragment by nested-PCR, are established for studying of genetic diversity of phytoplasma associated with diseases of sugarcane and some grasses in Thailand.In this present study, 99 phytoplasma infected sugarcane samples exhibiting various phenotypic symptoms and 15 samples of grasses showing white leaves were collected from many locations in Thailand and subjected for nucleotide sequencing. Phylogenetics tree based on 16S-23S ITS gene sequences showed two primary clusters: (1) phytoplasmas that cause diseases in sugarcane and (2) phytoplasmas that cause diseases in grasses. The phytoplasmas of sugarcane cluster was further divided into two subgroups that are (i) the sugarcane white leaf (SCWL) and sugarcane grassy shoot (SCGS) and (ii) sugarcane green grassy shoot (SCGS). Nucleotide sequence analysis revealed those 48 sequences of phytoplasma from green leaf, partial or complete chlorosis symptom, matched exactly with sugarcane white leaf; SCWL (HQ917068.1) while 41 sequences that showed grassy shoot symptom with partial or complete chlorosis showed sequence variations. Of these, 37 sequences matched exactly with SCGS (AB243298.1) and 4 sequences shared 99% sequence similarity with SCWL and SCGS. While sequences of the 6 samples exhibiting nonchlorosis grassy shoot showed distinct nucleotide sequences from SCWL and SCG. This article is the first report to reveal the sequences of the green grassy shoot phytoplasma in sugarcane. These divisions based on 16S-23S ITS sequence datacan be utilized for further study in couple with other genes in phytoplasma genome for a better differentiation and identification of the phytoplasma associated with sugarcane disease in Thailand