International trade in plants, especially with potting substrates, is recognised as the main pathway of plant pathogen dissemination on a global scale. In the last 20 years, the wide use of internet commerce has become common in the nursery sector and, due to the nature of online sales, may be aggravating this risk. Oomycetes in the genera Phytophthora, Pythium and Phytopythium, cause a range of important plant diseases, responsible for serious economic and biological losses. This research focused on the detection of Oomycetes in imported potted ornamental plants in the UK and The Netherlands, including internet sales and asymptomatic plants. Isolation techniques and molecular protocols were developed to quantify pathogen load in ornamental plants, using TaqMan PCR and Next Generation Sequencing (NGS) to assess Oomycete diversity using a multi-locus approach. Survival of Phytophthora cinnamomi and Fusarium verticillioides was estimated in two commercial potting mixes used in ornamental plant production. Oomycetes were detected in all samples analysed with the NGS approach, with 38 Phytophthora spp. and 48 Pythium/Phytopythium spp. identified. Phytophthora ramorum, P. alni subsp. alni and P. cryptogea were common. TaqMan PCR quantification showed high numbers of Oomycetes in all samples, especially in substrates, followed by roots and baiting waters. During sampling by isolation, Pythium kashmirense was recovered from Viburnum plicatum, the first record of this species in the UK. The survival experiment showed that Fusarium verticillioides remained viable after 17 months, whereas Phytophthora cinnamomi was viable up to 7 months after inoculation. This work clearly demonstrated the widespread presence of Oomycete pathogens in the plants for planting pathway. Moreover, the protocols developed and findings of this work contribute greatly to the understanding of the potential for pathogens to spread in the international horticultural trade and may help to improve plant biosecurity protocols in the UK and Europe.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:731635 |
| Date | January 2017 |
| Creators | Cerdà , Alexandra Puértolas |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=235373 |
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