A duplex real-time PCR with probe for simultaneous detection of Geosmithia morbida and its vector Pityophthorus juglandis

PLoS One. 2020 Oct 23;15(10):e0241109. doi: 10.1371/journal.pone.0241109. eCollection 2020.

Abstract

The cultivation of walnuts (Juglans sp.) in Europe retains high economic, social, and environmental value. The recent reporting of the Thousand Cankers Disease (TCD) fungus, Geosmithia morbida, and of its vector, Pityophthorus juglandis, in walnut trees in Italy is alarming the whole of Europe. Although Italy is at present the only foothold of the disease outside North America, given the difficulties inherent in traditional identification of both members of this beetle/fungus complex, a rapid and effective protocol for the early detection and identification of TCD organisms is an absolute priority for Europe. Here we report the development of an effective and sensitive molecular tool based on simplex/duplex qPCR assays for the rapid, accurate and highly specific detection of both the bionectriaceous fungal pathogen and its bark-beetle vector. Our assay performed excellently, detecting minute amounts of target DNA without any non-specific amplification. Detection limits from various and heterogeneous matrices were lower than other reported assays. Our molecular protocol could assist in TCD organism interception at entry points, territory monitoring for the early identification and eradication of outbreaks, delineation of quarantine areas, and tracing back TCD entry and dispersal pathways.

Publication types

  • Evaluation Study

MeSH terms

  • Animals
  • DNA, Environmental / genetics
  • DNA, Environmental / isolation & purification*
  • DNA, Fungal / isolation & purification
  • Hypocreales / genetics*
  • Insect Vectors / genetics
  • Insect Vectors / microbiology
  • Italy
  • Juglans / microbiology*
  • Limit of Detection
  • Plant Diseases / microbiology
  • Plant Diseases / prevention & control
  • Real-Time Polymerase Chain Reaction*
  • Reproducibility of Results
  • Weevils / genetics*
  • Weevils / microbiology

Substances

  • DNA, Environmental
  • DNA, Fungal

Supplementary concepts

  • Geosmithia morbida

Grants and funding

The authors received no specific funding for this work