Standardizing the Nomenclature for Clonal Lineages of the Sudden Oak Death Pathogen, <i>Phytophthora ramorum</i>

Grünwald, Niklaus J.; Goss, Erica M.; Ivors, Kelly; Garbelotto, Matteo; Martin, Frank N.; Prospero, Simone; Hansen, E. M.; Bonants, P.J.M.; Hamelin, Richard; Chastagner, Gary A.; Werres, Sabine; Rizzo, David M.; Abad, Gloria; Beales, Paul; Bilodeau, Guillaume J.; Blomquist, C. L.; Brasier, C. M.; Brière, S. C.; Chandelier, Anne; Davidson, Jennifer; Denman, Sandra; Elliott, Marianne; Frankel, Susan J.; Goheen, E. M.; Gruyter, Hans de; Heungens, Kurt; James, D.; Kanaskie, Alan; McWilliams, Michael; Veld, Willem Man in 't; Moralejo, Eduardo; Osterbauer, Nancy; Palm, Mary E.; Parke, Jennifer L.; Pérez-Sierra, A.M.; Shamoun, Simon F.; Shishkoff, Nina; Tooley, Paul W.; Vettraino, Anna Maria; Webber, Joan; Widmer, Timothy L.

doi:10.1094/phyto-99-7-0792

Cited by 102 publications

(61 citation statements)

References 38 publications

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“…• The distribution of lineages was reported as follows (using the nomenclature suggested by Grünwald et al, 2009): NA1 in North American nurseries and forests, NA2 in North American nurseries, EU1 in European nurseries. The evidence presented in that study indicated that introduction in nature in the USA most likely had been unwittingly aided by the sale and/or movement of infected nursery plants.…”

Section: Pest Categorisationmentioning

confidence: 99%

Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA

Rossi¹

2011

EFSA Journal

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The Panel on Plant Health was asked to deliver a scientific opinion on the Pest Risk Analysis on Phytophthora ramorum prepared by the FP6 project RAPRA, taking into account comments by Member States and additional information since RAPRA. P. ramorum is the oomycete causing sudden oak death in the USA and leaf and twig blight/dieback on a range of ornamental species in North America and Europe. Currently P. ramorum is not listed as a harmful organism in Council Directive 2000/29/EC, but the Commission adopted in 2002 provisional emergency measures to prevent introduction into and spread within the EU. Recent large-scale outbreaks in Japanese larch (Larix kaempferi) plantations in the UK and Ireland have worsened the potential consequences in the risk assessment area. However, the Panel concludes that the broad narrative in the RAPRA report stands and supports its conclusion that "There is a risk of further entry (of known or new lineages and/or mating types), establishment and […] impact". It is advisable to avoid introductions of different lineages because of inherent phenotypic differences and the potential for sexual recombination. The Panel supports the management options proposed in the RAPRA report and adds further measures for consideration. Uncertainty remains over the extent to which the association between control measures and gradual reduction in the number of cases in nurseries is causal. The emergency measures have not prevented outbreaks occurring in the natural environment. The many other remaining uncertainties (fitness of progeny, hybridisation with other Phytophthora species, host range and epidemiological role of new hosts, early detection of new outbreaks, understanding of long-range dispersal, structure of plant trade networks, origin of the pathogen) call for further research on P. ramorum across Europe. 4 Editorial changes have been made on pages 51 (acronym PRA removed as it was not in line with the Panel's dictionary as discussed in Appendix 2 of the Guidance on a harmonised framework for pest risk assessment and the identification and evaluation of pest risk management options by EFSA) and 89 (statement which referred to the Panel agreeing with the RAPRA conclusion that "P. ramorum fulfils the criteria of a quarantine pest" was removed as requested by the Panel during adoption of the draft opinion). The changes do not affect the overall conclusions of the opinion. To avoid confusion the original version has been removed from the website. The scope of this Scientific Opinion is the evaluation of the RAPRA report, taking into consideration the comments of Member States as well as additional information published after finalisation of the RAPRA report, or not cited in the RAPRA report. A systematic literature search until March 2011 was carried out. It should be noted that the scientific community is concerned by the shift of P. ramorum to new hosts (with a special focus on the Japanese larch) and its further spread, and therefore new results of ongoing research are constantly be...

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Section: Pest Categorisationmentioning

confidence: 99%

Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA

Rossi¹

2011

EFSA Journal

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“…As the understory vegetation sustains the pathogen and allows efficient proliferation (sporulation) in an epidemic of SOD, the appearance of "sudden larch death" represents a new life strategy of P. ramorum, because it is shown to sporulate efficiently high in the tree canopy. Isolates of P. ramorum examined to date comprise three distinct lineages: EU1, NA1 and NA2 (Ivors et al 2004, Ivors et al 2006, Grünwald et al 2009). The European populations of P. ramorum consist solely of EU1 genotypes and represent predominantly A1 mating type (Grünwald et al 2009, Werres & De Merlier 2003.…”

Section: New Species Of Phytophthora In Nurseries and Natural Ecosystemsmentioning

confidence: 99%

“…Isolates of P. ramorum examined to date comprise three distinct lineages: EU1, NA1 and NA2 (Ivors et al 2004, Ivors et al 2006, Grünwald et al 2009). The European populations of P. ramorum consist solely of EU1 genotypes and represent predominantly A1 mating type (Grünwald et al 2009, Werres & De Merlier 2003. NA1 consists of only a single genotype, which is responsible for SOD and is the most widespread genotype in US nurseries (Ivors et al 2006).…”

Section: New Species Of Phytophthora In Nurseries and Natural Ecosystemsmentioning

confidence: 99%

Phytophthora in Finnish nurseries

Rytkönen¹

2011

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International trade and travel have facilitated the spread of harmful organisms around the world. Human-mediated movement of plants and plant products is now generally accepted to be the primary mode of introduction of pathogens and pests. Species of Phytophthora, a genus of plant pathogens, are commonly spread in this way and have caused severe epidemics in silviculture, horticulture and natural systems all over the world.The objective of the study was to gather information on the occurrence of Phytophthora spp. in Finnish nurseries. Furthermore, the aim was to produce information for risk assessments for these Phytophthora spp. and establish molecular means for their detection. Phytophthora cactorum was found to persist in natural waterbodies and results suggest that irrigation water might be a source of inoculum for the disease in nurseries. In addition to P. cactorum, isolates from ornamental Rhododendron in nurseries yielded three species new to Finland: P. ramorum, P. plurivora and P. pini. The only species with quarantine status, P. ramorum, was able to persist in the nursery in spite of an annual European Commission sanitation protocol. Phytophthora plurivora and the closely related P. pini had more hosts among Nordic tree species and other plants abundant in Finnish nurseries and forest ecosystems. They were also found to have higher infectivity rates compared to P. ramorum and P. cactorum. All four species survived two weeks in -5 °C , and thus soil survival of these Phytophthoras in Finland is likely under current climatic conditions.The most common tree species in Finnish nurseries, Picea abies, was highly susceptible to P. plurivora and P. pini in pathogenicity trials. In a histological examination of P. abies shoot tissues inoculated with P. plurivora zoospores, fast necrotrophic growth was observed in nearly all tissues of the fresh shoot. The production of propagules in P. abies shoot tissue was only weakly indicated.In this study, a PCR-DGGE technique was developed for simultaneous detection and identification of Phytophthora spp. It reliably detected Phytophthora in plant tissues and could discriminate most test species as well as indicate instances of multiple-species infections. It proved to be a useful detection and identification tool either applied alone or in concert with traditional isolation culture techniques. The limitations of the method are also discussed.In conclusion, all of the introduced species of Phytophthora had properties that promote a high risk of establishment and spread in Finland. The efficient transport of Phytophthora via commercial traffic and favorable conditions due to expected climate change will increase the incidence and establishment of Phytophthora in new areas. Thus, it is probable that pathogens of this genus will be introduced and become established in Finland and other Nordic countries unless efficient phytosanitary control becomes standard practice in the international plant trade.Keywords: Phytophthora, pathogenicity, survival, molecular detectio...

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“…Growth rate was determined on V8 agar by measuring the colony diameter after 7 days' incubation at 20°C in the dark. Sporangia were dislodged from 10-day-old cultures on diluted (10% clarified juice) V8 agar using 20 ml of sterile MilliQ water and a glass rod, then quantified a Lineage according to Grünwald et al (2009). Multilocus genotype according to Vercauteren et al (2010) b Different from EU1MG1 with an AFLP marker c R resistant; S sensitive.…”

Section: Phenotypic Characterization In Vitromentioning

confidence: 99%

Genotypic and phenotypic characterization of the European A2 isolates of Phytophthora ramorum

et al. 2010

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Phytophthora ramorum, a recently described North American and European pathogen, has three clonal lineages. The NA1 and NA2 lineages are found in North American forests and nurseries, while the EU1 lineage appears mainly in European nurseries. P. ramorum is heterothallic, having two mating types A1 and A2. All NA1 and NA2 isolates are of A2 mating type. When first collected, all EU1 isolates were of A1 mating type, with the exception of one A2 isolate collected in Belgium in 2002. Screening 410 other Belgian isolates for mating type revealed two additional EU1-A2 isolates collected in 2002 and 2003. PCR-RFLP, AFLP and SSR markers were used to determine the nature of the mating type change. The three isolates show no indications of sexual recombination or mitotic crossing over, indicating that mutation or mitotic gene conversion is the most likely explanation for the mating type change. We compared the pathogenicity and sporulation characteristics of the EU1-A2 isolates to those of EU1-A1 and NA1-A2 isolates on four host plants. Despite small differences in pathogenicity on some hosts, the EU1-A2 isolates were similarly aggressive to each other and to the EU1-A1 isolates and more aggressive than the NA1-A2 isolates. Sporulation characteristics were also comparable among EU1-A2 isolates and between EU1-A1 and EU1-A2 isolates, except for EU1-A2 isolate BBA 26/02. The limited genotypic and phenotypic differences between EU1-A2 isolates probably evolved after the mating type change, which may have occurred several years before the isolates were detected. There are strong indications that the EU1-A2 population has been eradicated from Belgium

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Standardizing the Nomenclature for Clonal Lineages of the Sudden Oak Death Pathogen, Phytophthora ramorum

Cited by 102 publications

References 38 publications

Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA

Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA

Phytophthora in Finnish nurseries

Genotypic and phenotypic characterization of the European A2 isolates of Phytophthora ramorum

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