First Report of Soybean mosaic virus on Soybean in North Dakota.

Soybean, Glycine max L, is grown on 1,420,000 ha in North Dakota and is the most important oilseed crop in the state. Viruses in soybean have not previously been reported from North Dakota (2). In July and August of 2007, 64 soybean fields in Cass, Richland, and Sargent counties in southeastern North Dakota were surveyed for Soybean mosaic virus (SMV). These counties have a high concentration of soybean hectares, a long history of soybean production, and soybean aphid infestations that were observed in 2004 and 2006. Fields were sampled with a grid pattern across the area with at least 8 km (5 miles) between fields. A transect of approximately 60 m through each field was made and 20 leaves were collected at random. Sap was extracted in phosphate buffer and stored at -80°C until tested first using double antibody sandwich (DAS)-ELISA with positive controls and reagents and protocol from Agdia Inc. (Elkhart, IN). Using DAS-ELISA, SMV was detected in 19 of the 64 soybean fields sampled. To confirm the presence of SMV, 12 samples that were positive for SMV by DAS-ELISA also were tested by reverse transcription (RT)-PCR. RNA was extracted from sap by a Qiagen RNeasy Plant Mini Kit (Germantown, MD), reverse transcribed, and amplified with SuperScrip III Platinum SYBR Green One-Step qRT-PCR Kit (Invitrogen Inc., Carlsbad, CA) and SMV-specific primers (5'-TTCAGCACAATGGGTGAGGATG-3' and 5'-AATTCTGTGTGGCTTGATGTTGC-3') (1). Eight of the twelve ELISA-positive samples were positive for SMV by RT-PCR, confirming the presence of SMV in the samples. To our knowledge, this is the first report of SMV infecting soybean in North Dakota. References: (1) L. L. Domier et al. (Abstr.). Phytopathology 98(suppl.):S47, 2008. (2) B. D. Nelson and G. Danielson. (Abstr.). Phytopathology 95(suppl.):S164, 2005.