Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2006
Publication Date: 10/27/2006
Citation: Shao, J.Y., Jomantiene, R., Dally, E.L., Zhao, Y., Lee, I., Nuss, D.L., Davis, R.E. 2006. Phyogeny and characterization of phytoplasma NusA and use of the nusA gene in detection of group 16SrI strains. Journal of Plant Pathology. 88:193-201. Interpretive Summary: Phytoplasmas are very small bacteria that are responsible for hundreds of diseases affecting agriculturally important plants around the world. Phytoplasmas are unlike most bacteria, in that they have no cell wall, and they cannot be isolated in laboratory culture. There is need to improve methods and tools for detecting and identifying phytoplasmas in order to aid efforts to curb the spread of diseases caused by phytoplasmas. In a study of the genome (all of the genes) in a phytoplasma, we have cloned and determined the nucleotide sequence of the gene encoding the protein NusA, which is important in the process that transfers genetic information from DNA to RNA for the synthesis of proteins, and we have compared the phytoplasma’s NusA protein to NusA proteins from other bacteria. The results of our study provide new information about the evolution of genes that are important for protein synthesis, and provide a new molecular tool for phytoplasma detection and identification. This work will interest scientists and students studying the evolution of bacteria, plant diseases, and diagnostics companies and centers involved in pathogen detection.
Technical Abstract: Nucleotide sequence analysis of a cloned 4.6 kbp fragment of clover phyllody (CPh) phytoplasma genomic DNA revealed five potential coding sequences (open reading frames, ORFs), including one encoding NusA, a general transcription factor in prokaryotes modulating pausing, termination, and anti-termination by association with the core enzyme of RNA polymerase. For comparisons, the nusA gene was cloned and sequenced from Acholeplasma palmae. Phylogenetic analysis indicated that phytoplasmal and acholeplasmal nusA genes diverged from a common ancestor. Amplification of nusA gene sequences in the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis of PCR products permitted detection and differentiation of diverse phytoplasmas belonging to group 16SrI, ‘Candidatus Phytoplasma asteris’-related strains. The nusA gene of CPh phytoplasma was flanked at its 5’-end by a hypothetical protein gene and a partial smpB gene, and at its 3’-end by a hypothetical protein gene that may be coordinately regulated with nusA and a partial infB (translation initiation factor) gene.