Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/16/2006
Publication Date: 7/29/2006
Citation: Barnes, C.W., Szabo, L.J., Johnson, J.L., Bowersox, V.C., Harlin, K.S. 2006. Detection of Phakopsora pachyrhizi spores in rain using real-time PCR assay [abstract]. Journal of Phytopathology. 96:59.
Technical Abstract: In 2005, rain samples were collected weekly at selected National Atmospheric Deposition Program (NADP) sites in the eastern and central US and screened for Phakopsora pachyrhizi (Asian soybean rust) spores. A nested real-time PCR assay was used to detect P. pachyrhizi DNA in the filter residue. A subset of 32 rain collections in January and February were used for assay development. The final assay was used to screen 1,644 samples collected from May-August. The lower limit of the assay was roughly 1–10 spores per sample based on spiking experiments. P. pachyrhizi spores were detected as early as February in Louisiana. The number of positive samples increased through May across the southeastern US, from western Texas to South Carolina. By the end of August, 86 positive samples were detected across the eastern US, from Texas to North Dakota and Florida to upstate New York. The highest number of positives during a given week occurred at the end of May and middle of August. Verification of positive samples in the Dakotas, Minnesota, Wisconsin, Indiana, and Missouri was done through DNA sequencing of the assay amplicon. This study demonstrates the use of a PCR assay to detect spores in rain collected at geographically dispersed NADP sites, and can serve as a powerful tool for understanding the aerial transport of spores in the atmosphere. Annual Meeting of APS. Quebec City, Quebec Canada, July 29 - August 2, 2006.