DIFFERENTIATION OF TWO EGYPTIAN ISOLATES OF SPIROPLASMA CITRI BASED ON 16S RDNA, SPIRALIN GENES AND 16S123S RDNA INTERGENIC SPACER REGIONMAN F. OMAR, H. HABIBUDDIN, 1KAMARUZAMAN SIJAM, ZANIAL A.M. AHMAD AND M-HASHEM M. EE-BANANA
Two Egyptian isolates of Spiroplasma citri (Fewa and Qualubia) were studied based on nucleotide sequences of their spiralin and I6S rDNA genes and 16S/23S rDNA intergenic spacer region sequence. The 16S rDNA of the two isolates comprised I 529 nucleotides with a similarity between them at 99.80% where only two different nucleotides were observed. Both have more than 99.67% similarity to three published strains of S. citri, R8A2HP, Car4 and Car6. Their 16S/23S rDNA intergenic spacer region has 305 nucleotides, with a similarity of about 99.76 %, where only one nucleotide difference was observed. The 16S/23S nucleotide sequence of Fewa isolate was identical to that of strains 169, Maroc and ATCC 27556. Five nucleotide differences were observed in spiralin gene sequences of the two isolates, which has 99.30 % similarity. Both the two spiralins comprised 241 amino acids and only three amino acids differences were observed between them, and their amino acids similarity was about 98.75%. Our findings indicated that both Fewa and Qualubia isolates have high similarity in the nucleolide sequences of their 16S rDNA, 16S/23S rDNA intergenic spacer region and the nucleotides and amino acids of spiralin gene. However, they were not identical and could be differentiated by using restriction enzyme Bfa\ that digested at the recognition site CTAG within their spiralin gene sequence.
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