PhytoFrontiers (Apr 2021)

Effect of Ozone on Inactivation of Purified Pepper Mild Mottle Virus and Contaminated Pepper Seed

  • John R. Stommel,
  • Judith M. Dumm,
  • John Hammond

DOI
https://doi.org/10.1094/PHYTOFR-09-20-0020-R
Journal volume & issue
Vol. 1, no. 2
pp. 85 – 93

Abstract

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Pepper mild mottle virus (PMMoV) is a major viral pathogen of pepper (Capsicum spp.). PMMoV is readily mechanically transmitted and is seed transmissible. Trisodium phosphate (TSP) treatment is commonly used to reduce the level of viable PMMoV in contaminated seed. Ozone is efficacious in disinfecting fungal-contaminated seed and disrupting bacterial and viral pathogens on various substrates. The purpose of this study was to evaluate efficacy of ozone and chemical treatment on PMMoV viability. Treated pepper seed infectivity was evaluated via bioassay with Nicotiana benthamiana. Symptoms of PMMoV infection were not observed in bioassays of TSP-treated seed. Sufficient viable PMMoV remained on ozone-treated seed to cause infection, which was confirmed by ELISA. Neither treatment affected seed germination. Ozone treatment of purified PMMoV was assessed to determine the extent, if any, of PMMoV inactivation by ozone. At the low PMMoV concentration (0.01 mg/ml), 14-h ozone exposure eliminated infectivity as determined by N. benthamiana bioassays with ELISA confirmations. At the higher PMMoV concentration (0.1 mg/ml), ozone treatment was insufficient to prevent infection. Ozone inactivation of purified PMMoV was quantified via bioassay using the local lesion host N. glutinosa and quantitative real-time PCR. Ozone exposure reduced lesion counts and PMMoV concentration, and PMMoV degradation increased with exposure time. Although PMMoV infection was eliminated at the low PMMoV concentration, bioassays using naturally infected seed and purified PMMoV preparations at relatively higher concentrations demonstrated that ozone is not efficacious as a standard treatment to sufficiently reduce levels of infective PMMoV in contaminated pepper seed.[Graphic: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

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