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A population analysis of Puccinia emaculata using single spores in Oklahoma and Virginia
J. C. PAVLU (1), G. Orquera (2), O. Arias (3), A. Moya (4), S. M. Marek (5), C. Garzón (5). (1) Oklahoma State University, Perkins, OK, U.S.A.; (2) Oklahoma State University, Stillwater , OK, U.S.A.; (3) Escuela Politécnica del Ejército, Sangolquí, Ecuador; (4) PUCE - Pontificia Universidad Católica del Ecuador, Quito, Ecuador; (5) Oklahoma Stat

Native to the North American prairies, <i>Panicum virgatum,</i> most commonly known as Switchgrass, has been chosen for biofuel production due to its low input cost of production and high feed stock quality. However, a rust pathogen (<i>Puccinia emaculata</i>) has become a major threat to Switchgrass causing significant widespread biomass reductions. The objective of this study was to spatially and temporally analyze the population dynamics of switchgrass rust over a period of two years (2011 and 2012) between two different states, Virginia and Oklahoma.  Individual <i>P. emaculata</i> urediniospores were collected and whole genome amplified. Following confirmation of the rust genus and species, 20 previously designed microsatellite loci were screened. Four microsatellites consistently produced polymorphic amplicons. Our results indicate that the 2011 population from Virginia was the most unique, while the 2011 and 2012 Oklahoma populations and the 2012 Virginia population were not significantly different. These findings suggest a possible movement of alleles through migration along the <i>Puccinia </i>pathway.  Population analysis of representative population samples over space and time, will allow a better understanding of the epidemiology and movement of the rust pathogen, which will lead to the development of best management practices.

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