Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum.

Phytopathology (Impact Factor: 2.75). 08/2009; 99(7):792-5. DOI: 10.1094/PHYTO-99-7-0792
Source: PubMed

ABSTRACT Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. Here we propose a system for naming clonal lineages of P. ramorum based on a consensus established by the P. ramorum research community. Clonal lineages are named with a two letter identifier for the continent on which they were first found (e.g., NA = North America; EU = Europe) followed by a number indicating order of appearance. Clonal lineages known to date are designated NA1 (mating type: A2; distribution: North America; environment: forest and nurseries), NA2 (A2; North America; nurseries), and EU1 (predominantly A1, rarely A2; Europe and North America; nurseries and gardens). It is expected that novel lineages or new variants within the existing three clonal lineages could in time emerge.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Phytophthora ramorum is known to infect a number of ornamental plants grown in containerized culture. However, pots may also contain weeds. In this research, the foliage of 14 common weeds of containerized plant culture was inoculated with P. ramorum to determine susceptibility of aboveground parts. Three species were found to develop leaf lesions: northern willowherb (Epilobium ciliatum), fireweed (Chamerion angustifolium), and a fern (Pteris cretica). Weed roots from 11 species were inoculated to see if P ramorum could persist on roots, and P ramorum was isolated from most plant roots 1 month after inoculation when the washed roots were plated on selective medium; they were recovered only to a minor extent from surface-sterilized roots of weeds. Additional experiments were done to collect and sample runoff from pots containing inoculated plants to see if inoculum was produced on weed roots. In these experiments, little inoculum was found in runoff from root-inoculated weeds compared to Viburnum tin us. Percent root colonization recorded from washed roots was significantly greater in Viburnum compared to the weeds, and weeds that were foliar hosts had greater root colonization than weeds that were not.
    Plant Disease 07/2012; 96(7):1026-1032. DOI:10.1094/PDIS-09-10-0695-RE · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Little is known about colonization of roots of trees by Phytophthora ramorum. We examined zoospore concentration and exposure time needed to infect six Quercus (oak) species and the inoculum produced from their roots. Sprouted acorns, exposed to zoospores (3,000/ml) for different times and transplanted to potting soil, were susceptible to infection within 1 h of exposure but root weights were not impacted after 4 weeks (P = 0.952). Roots of Quercus prinus seedlings, inoculated with sporangia, had 0.6 to 3.2% colonization of the total root mass after 5 months. Neither root lesions nor obvious root sloughing were observed. Inoculum threshold levels were tested by exposing radicles to varying zoospore concentrations for 24 h. Results showed that radicle infection occurred even at 1 zoospore/ml. To test inoculum production, roots were inoculated with sporangia and transplanted into pots. Periodically, samples of runoff were collected and plated on selective medium. Afterward, root segments were plated to calculate percent colonization. After 16 and 35 days, root colonization and inoculum production from oak was lower than that of Viburnum tinus, a positive control. This study shows that P ramorum is able to infect sprouted oak acorns and produce secondary inoculum, which may be important epidemiologically.
    Plant Disease 11/2012; 96(11):1675-1682. DOI:10.1094/PDIS-12-11-1024-RE · 2.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species) of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues.
    The plant pathology journal 12/2014; 30(4):331-42. DOI:10.5423/PPJ.RW.07.2014.0068 · 0.76 Impact Factor

Full-text (2 Sources)

Available from
Jun 3, 2014