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POSTERS: Pathogen detection, quantification and diagnosis

Enhanced Detection of Bacterial Blights on Common Bean
Katie Nelson - Dept of Plant Pathology, North Dakota State University. Julie Pasche- Dept of Plant Pathology, North Dakota State University, Robin Lamppa- Dept of Plant Pathology, North Dakota State University, Amanda Beck- Seneca Foods, Kristin Simons- Dept of Plant Sciences, North Dakota State University

The common bean growing region in North Dakota and Minnesota accounts for over 35% of acres harvested nationwide. A bacterial blight complex affects nearly all common beans in the region to some extent annually. The three most common bacterial diseases in this region include: common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli (Xap) and X. fuscans subsp. fuscans (Xff), bacterial brown spot caused by Pseudomonas syringae pv. syringae (Pss), and halo blight caused by Pseudomonas syringae pv. phaseolicola (Psp). Simplex PCR assays exist for each of these pathogens; however, the development of a multiplex qPCR assay will enable the quantification of each pathogen in the complex simultaneously from seed, pod, and leaf tissue. Primer sets of Xap, Xff, and Psp optimized only the target bacteria among 27 target and non-target bacterial species tested for primer specificity. Standard curves for the multiplex assay established for Xap, Xff, Psp, and Pss produced efficiency values of 90.9%, 93.1%, 94.4% and 91.5%, respectively. R2 values were 0.99 for all assays. Pathogen detection of the four target species was successful on 30 diseased leaf tissue samples. Preliminary results indicate a significant positive correlation between traditional plating methods and qPCR detection from seed in field trials conducted in Oakes, ND in 2016 (P<0.0001; r = 0.85) and Fargo, ND in 2017 (P<0.0001; r = 0.56).