Effect of Soybean Vein Necrosis on Soybean Yield and Seed Quality, and Symptom Expression on Soybean and Alternative Hosts
Soybean vein necrosis virus (SVNV) is the causal agent of soybean vein necrosis (SVN) on soybean (Glycine max (L.) Merr.). Like others in the Tospovirus family, SVNV is vectored by thrips, specifically soybean thrips (Neohydatothrips variabilis (Beach)). This virus was first described in 2011, and the impact of the virus and disease on soybean yield were previously unknown. A multi-state research project was conducted to determine the effect of SVN on soybean yield and quality, and results indicate that SVN does not affect yield, but does impact seed quality. Seed from plants symptomatic of SVN had lower oil content in 2014 and 2015 (P=0.04, P<0.01).
Because the virus is new to soybean production regions, the host range is not well-defined and there are no prior studies on soybean varietal resistance to SVN. Common Indiana weed species were tested to assess SVN symptom expression, and determine if weed species could be alternative hosts for SVNV. Four weed species, ivyleaf morning glory (Ipomoea hederacea Jacq.), pitted morning glory (Ipomoea lacunose L.), redroot pigweed (Amaranthus retroflexus L.), and palmer amaranth ( Amaranthus palmeri S. Wats.) were infested using SVNV-infected soybean thrips and were tested for the presence of SVNV. Infection rates were relatively low on the weed species, preventing confirmation of any new alternative hosts. Significant differences in disease severity were observed among soybean varieties tested (P<0.0001). SoyNAM population lines LG94-1906, Skylla, PI561.370 and PI507.681B, the public variety Hutcheson, and the commercial variety Mycogen 5N342RR were infested using SVNV-infected soybean thrips and rated for SVN symptoms. LG94-1906 exhibited highest SVN severity (20.6%) while PI 561.370 (8.0%), Skylla (6.25%), and Mycogen 5N342 R (5.3%) had lower SVN severity. The results obtained from these three experiments indicate that SVN can negatively impact soybean seed quality and that variety selection may influence disease severity. While no new alternative hosts were confirmed due to low disease incidence, confirmatory testing of SVNV indicated that the virus was present in asymptomatic plants, meaning that the role of Indiana weeds in the lifecycle of SVNV requires further examination.
Wise, Purdue University.
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