Soybean cyst nematode culture collections and field populations from North Carolina and Missouri reveal high incidences of infection by viruses.

Casey L Ruark,Stephen R Koenning,Melissa G Mitchum,Charles H Opperman,Steven A Lommel,Eric L Davis,Tim L Sit

doi:10.1371/journal.pone.0171514

Casey L Ruark, Stephen R Koenning + Show 5 more

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https://doi.org/10.1371/journal.pone.0171514

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Journal: PloS one	Publication Date: Jan 31, 2017
Citations: 14	License type: CC BY 4.0

Affiliation: North Carolina State University, University of Missouri

Abstract

Five viruses were previously discovered infecting soybean cyst nematodes (SCN; Heterodera glycines) from greenhouse cultures maintained in Illinois. In this study, the five viruses [ScNV, ScPV, ScRV, ScTV, and SbCNV-5] were detected within SCN greenhouse and field populations from North Carolina (NC) and Missouri (MO). The prevalence and titers of viruses in SCN from 43 greenhouse cultures and 25 field populations were analyzed using qRT-PCR. Viral titers within SCN greenhouse cultures were similar throughout juvenile development, and the presence of viral anti-genomic RNAs within egg, second-stage juvenile (J2), and pooled J3 and J4 stages suggests active viral replication within the nematode. Viruses were found at similar or lower levels within field populations of SCN compared with greenhouse cultures of North Carolina populations. Five greenhouse cultures harbored all five known viruses whereas in most populations a mixture of fewer viruses was detected. In contrast, three greenhouse cultures of similar descent to one another did not possess any detectable viruses and primarily differed in location of the cultures (NC versus MO). Several of these SCN viruses were also detected in Heterodera trifolii (clover cyst) and Heterodera schachtii (beet cyst), but not the other cyst, root-knot, or reniform nematode species tested. Viruses were not detected within soybean host plant tissue. If nematode infection with viruses is truly more common than first considered, the potential influence on nematode biology, pathogenicity, ecology, and control warrants continued investigation.

Highlights

Until recently, plant parasitic nematodes (PPN) of the genera Longidorus, Trichodorus, and Xiphinema were the only nematodes known to harbor viruses, but these genera serve as vectors of plant viruses and replication does not occur within the worm [1,2,3]
Total RNA was extracted from 0.1 g of tissue from the leaves, stems, roots, and pods of 1 to 3 month-old soybean plants non-infected with soybean cyst nematodes (SCN) in a greenhouse at North Carolina State University (NCSU)
The soybean cultivars Bedford, Hartwig, Jake, NC Raleigh, NC Roy and Williams 82 were tested for viruses via qRT-PCR

Summary

Introduction

Plant parasitic nematodes (PPN) of the genera Longidorus, Trichodorus, and Xiphinema were the only nematodes known to harbor viruses, but these genera serve as vectors of plant viruses and replication does not occur within the worm [1,2,3]. Few studies have attempted to demonstrate viral replication in nematodes. An early study observed that root knot nematode. PLOS ONE | DOI:10.1371/journal.pone.0171514 January 31, 2017

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