Grower Alert: First Seed-to-Plant Spread of Harmful Soybean Virus Proven by UW-Madison

BY David Schiff | January 27, 2016 - 

For the first time, a UW-Madison study has proven a crop-injuring Tospovirus can be passed from soybean seeds to plants, a finding with significant implications for soybean production around the world.

The landmark study shows the virus can spread from an infected seed lot to seedlings at a rate of 6%, which affects seed quality and reduces total oil content. Until now, Tospovirus transmission in this manner was unproven and thought unlikely.

Unchecked, the virus—called Soybean vein necrosis virus (SVNV)—could reduce the production of high quality, pathogen-free seed and soybean oil yields.

Armed with this new knowledge, soybean growers should work to preserve clean seed lots to help prevent SVNV damage in breeding nurseries and in the field. Further, UW-Madison Plant Pathologist Dr. Damon Smith urges seed producers to be diligent about scouting their crop and testing plants for SVNV so the virus is not transmitted to the next soybean generation.

Given the industry demand for high-oleic production, farmers should be aware that SVNV can reduce oil content in soybeans so it’s prudent to source soybean seeds from producers who use vigilant SVNV screening measures.

Dr. Smith points out there is no risk to animal or public health from Tospovirus, but reduced oil production can have a negative effect on farm profitability.

The study, released on January 19, 2016,  has already sparked considerable interest around the world. Further research will be needed to understand why this particular virus can be seed transmitted. Smith suspects there may be multiple strains of the SVNV virus.

An abstract of this groundbreaking work follows below. Please go here to read the entire study—Groves et al., Seed Transmission of Soybean vein necrosis virus: The First Tospovirus Implicated in Seed Transmission, Web PLOS | ONE, 19 January 2016. <http://journals.plos.org>

This work was partially funded by the Wisconsin Soybean Marketing Board in combination with funding from the USDA. Given the impact of this finding for U.S. soybean producers, this is a “must know” study with clear action steps that the growers and farmers should use from now on.


Abstract (From the Attached Downloadable PDF)
Soybean vein necrosis virus (SVNV; genus Tospovirus; Family Bunyaviridae) is a negativesense
single-stranded RNA virus that has been detected across the United States and in
Ontario, Canada. In 2013, a seed lot of a commercial soybean variety (Glycine max) with a
high percentage of discolored, deformed and undersized seed was obtained. A random
sample of this seed was planted in a growth room under standard conditions. Germination
was greater than 90% and the resulting seedlings looked normal. Four composite samples
of six plants each were tested by reverse transcription polymerase chain reaction (RT-PCR)
using published primers complimentary to the S genomic segment of SVNV. Two composite
leaflet samples retrieved from seedlings yielded amplicons with a size and sequence predictive
of SVNV. Additional testing of twelve arbitrarily selected individual plants resulted in
the identification of two SVNV positive plants. Experiments were repeated by growing seedlings
from the same seed lot in an isolated room inside a thrips-proof cage to further eliminate
any external source of infection. Also, increased care was taken to reduce any
possible PCR contamination. Three positive plants out of forty-eight were found using these
measures. Published and newly designed primers for the L and M RNAs of SVNV were also
used to test the extracted RNA and strengthen the diagnosis of viral infection. In experiments,
by three scientists, in two different labs all three genomic RNAs of SVNV were amplified
in these plant materials. RNA-seq analysis was also conducted using RNA extracted
from a composite seedling sample found to be SVNV-positive and a symptomatic sample
collected from the field. This analysis revealed both sense and anti-sense reads from all
three gene segments in both samples. We have shown that SVNV can be transmitted in
seed to seedlings from an infected seed lot at a rate of 6%. To our knowledge this is the first
report of seed-transmission of a Tospovirus

Carol Groves 1, Thomas German 2, Ranjit Dasgupta 2, Daren Mueller 3, Damon L. Smith 1*
1 Department of Plant Pathology, University of Wisconsin, 1630 Linden Drive, Madison, WI, 53706, United
States of America, 2 Department of Entomology, University of Wisconsin, 1630 Linden Drive, Madison, WI,
53706, United States of America, 3 Department of Plant Pathology

Citation: Groves C, German T, Dasgupta R, Mueller
D, Smith DL (2016) Seed Transmission of Soybean
vein necrosis virus: The First Tospovirus Implicated in
Seed Transmission. PLoS ONE 11(1): e0147342.
doi:10.1371/journal.pone.0147342
Editor: Hanu R Pappu, Washington State University,
UNITED STATES

Received: June 26, 2015

Accepted: December 31, 2015

Published: January 19, 2016

Copyright: © 2016 Groves et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability Statement: All raw data files are available from the Dryad database at the following
URL: doi:10.5061/dryad.b1pg3.

Funding: Funding for this work was provided in part by the Wisconsin Soybean Marketing Board and the USDA-ARS Floriculture and Nursery Research Initiative. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

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