Cryptic Risks to Forest Biosecurity Associated with the Global Movement of Commercial Seed

Michelle Cleary (Corresponding Author), Funda Oskay, Hatice Tuğba Doğmuş, Asko Lehtijärvi , Stephen Woodward, Anna Maria Vettraino

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47 Citations (Scopus)
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The import and export of tree seed carries with it risks of inadvertent introduction of pests and pathogens to hitherto unaffected regions. Although trade in seed of specified trees is regulated, phytosanitary requirements for most tree species are minimal, even those related to the most important forest tree species in a given region. A better understanding of the microbiome associated with seed intended for commercial production or ornamental use, and their potential risk with the transport from the source origin of distributors, will help regulatory agencies implement measures to safeguard seed health and avoid trade-related spread of potentially harmful pathogens. In this study we used high-throughput sequencing to show that highly diverse fungal communities were associated with seed of 14 different Pinus species obtained from seed banks (seed orchards) and retail sources (online distributors) in North America and Europe. Fungal diversity differed among the 23 seedlots tested. Community composition did not relate to the species of Pinus nor the country of origin. Assigned potential functions based on sequence identity using FUNGuild provided an overall understanding of the likely life strategies of fungal operational taxonomic units (OTUs). Of those sequences classified to a trophic level, 453 were plant pathogens, with the Dothideomycetes having the highest prevalence. The most common plant pathogens included Sydowia polyspora, Lasiodiplodia theobromae, Diplodia intermedia and Diplodia sapinea that were detected from the majority of Pinus species. The evidence presented here illustrates an urgent need for plant protection authorities, practitioners and the general public to recognize the potential risk of introducing harmful pathogens through innocent transport of seed.
Original languageEnglish
Article number459
Number of pages16
Issue number5
Early online date27 May 2019
Publication statusPublished - May 2019

Bibliographical note

Funding: This research was funded by the Swedish Research Council FORMAS grant number 2018-00966, and the UK Forestry Commission. Support was also provided by the EU-COST Action FP 1406 “Pine pitch canker - strategies for management of Gibberella circinata in greenhouses and forests” (PINESTRENGTH).

Acknowledgments: We gratefully acknowledge laboratory support from Mohammed Elsafy, and the Forest Tree Seeds and Tree Breeding Research Directorate for providing the Turkish seeds. We gratefully acknowledge Dr. Alberto Santini from the Institute for Sustainable Plant Protection - C.N.R. in Italy for providing information on documented seed introductions to Europe from the international database he maintains.


  • alien invasive forest pathogens
  • emerging forest diseases
  • global trade
  • Pinus
  • Diplodia sapinea
  • Sydowia polyspora
  • Lasiodiplodia theobromae
  • mycobiome


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