Detection and Characterization of Two Phytoplasma Lineages on Cucumber (Cucumis Sativus L.) With Same Symptomatology Based on Virtual Rflp and Nucleotide Sequence Analysis of 16s Rdna

Abstract

Phytoplasma-like symptoms were observed in cucumbers (Cucumis sativus L.) in Van province of Turkey. The major symptoms observed were severe dwarfing, witches’ broom, rosetting, little leaf, and sterility of plants. Genomic DNA of 8 symptomatic and non-symptomatic plant leaves was isolated for the detection of pathogenic DNA. Of the 8 cucumber leaf samples tested by nested polymerase chain reaction (Nested-PCR), the four yielded the expected 1.25-kb DNA fragments when using universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Randomly selected two DNA bands were further cloned into a proper plasmid vector. The recombinant plasmid DNA was sequenced bidirectionally. BLAST and virtual restriction fragment length polymorphism (RFLP) analyses of the 16S rDNA sequence revealed the presence of the “Candidatus Phytoplasma solani” (similarity coefficient 1.00) (GenBank accession no: KX977570) in one of the severely symptomatic cucumber samples and the “Candidatus Phytoplasma trifolii” (similarity coefficient 0.98) (GenBank accession no.: KR080212) in the other. The isolates were designated as Van-trifolii and Van-solani isolates, respectively. No significant differences were observed between the two different phytoplasmas’ symptomatology. To the authors’ knowledge, this is the first report of ‘Ca. P. trifolii’ and ‘Ca. P. solani’ in cucumbers in Turkey. © 2017, Centenary University. All rights reserved.