Poster Session: Molecular and Cellular Plant-Microbe Interactions - Proteomics/Metabolomics/Genomics
757-P
Complete Genome Sequence of Spiroplasma kunkelii: New Insights Into Spiroplasma Evolution.
R. E. DAVIS (1), J. Shao (1), E. L. Dally (1), Y. Zhao (1), G. E. Gasparich (2), B. J. Gaynor (2), J. Athey (1), N. A. Harrison (3), N. Donofrio (4)
(1) Molecular Plant Pathology Laboratory, USDA-Agricultural Research Service, Beltsville, MD, U.S.A.; (2) Department of Biological Sciences, Towson University, Towson, MD, U.S.A.; (3) University of Florida, Ft. Lauderdale Research and Education Center, Da
The helical, motile, cell wall-less prokaryote infecting corn stunt diseased maize (Zea mays L.) plants and the insect vector Dalbulus maidis was the first spiroplasma discovered and is the microbe for which the term ‘spiroplasma’ was originally coined. The genome of this plant pathogen, Spiroplasma kunkelii, like that of the plant pathogen S. citri, has long resisted complete nucleotide sequence assembly because of numerous, homologous plectroviral genes that are integrated in the chromosome. In the present work, genomic DNA was extracted and purified from a culture of S. kunkelii strain CR2-3x grown in liquid medium. Nucleotide sequencing of the DNA followed by assembly of the sequence reads yielded a single circular chromosome and four plasmids. Comparison of the assembled chromosome with a previously constructed, detailed physical and genetic map of the S. kunkelii chromosome made it possible to verify that the sequence reads were correctly assembled to yield the first completely sequenced chromosome of a plant pathogenic spiroplasma. Comparative analysis of the S. kunkelii genome with the completely sequenced genomes of non-plant pathogenic members of class Mollicutes has opened new insights into the evolutionary emergence of plant pathogenic spiroplasmas.