Forest Investment Account (FIA) - Forest Science Program
FIA Project Y073203

    Genetic variation in the foliar pathogen Dothistroma septospora and relationship to toxin production
Project lead: Lewis, Kathy
Contributing Authors: Lewis, Kathy J.; Dale, Angie
Imprint: [Prince George, B.C.] : [University of Northern British Columbia], 2007
Subject: Forest Investment Account (FIA), Dothistroma Pini, Dothistroma Pini, effect of climate on, Pinus, Diseases and Pests, Vegetation and Climate, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
LOI: Research question and objectives of the project. These remain unchanged and can be found in the LOI appendix. FP: Dothistroma septospora (= Dothistroma pini) is a foliar pathogen of two and three needle pines, and is considered native to Central America and western North America, although it probably originated from South America. The fungus is spread primarily through splash dispersal of the conidia and causes a foliar blight on several pine species. Mild summer temperatures and prolonged periods of high humidity or surface water films contribute to serious outbreaks of the disease. In New Zealand, the fungus has caused serious damage in plantations of the exotic Pinus radiata, and in pine plantations in other regions of the southern hemisphere. The damage to plantations in New Zealand stemmed primarily from the introduction of the asexual stage (Dothistroma septospora), and although the fungus found an environment conducive to spread, and a susceptible host, genetic diversity of the pathogen population remained low due to the initial lack of the sexually reproducing form of the fungus (Mycosphaerella pini). This lack of genetic diversity in the fungus facilitated development of resistant pine stock for New Zealand plantations. In British Columbia, the sexual form of the fungus was found in 1966 on diseased foliage on several pine species on Vancouver Island. However, since those early descriptions, no work has been done on the genetic variation of the fungus in B.C. or on the variation in production of dothistromin, a toxin thought to be largely responsible for pathogenicity in the fungus. This is presumably because up until recently, the fungus has not caused serious, or even noteworthy, damage to natural stands or plantations of native pine species. Dothistromin is a toxin that has a major role in pathogenicity, and has also been shown to be a human mutagen that has properties common to aflatoxin B1 found on stored grains and nuts (e.g. peanuts) (Elliott et al. 1989). A study by Bradshaw et al. (2000) demonstrated that strains of D. septospora from Germany and the United States, produced dothistromin at over 500 and 40 times respectively, compared to New Zealand strains. One Canadian strain, from Vancouver Island, produced relatively low levels of toxin. Over the past three years, an outbreak of Dothistroma septospora has developed in the northwest Interior Cedar Hemlock zone near Smithers, B.C. High rates of mortality have been observed and most pine plantations in the region have suffered substantial damage. Several factors may be involved in the development of the outbreak, including repeated episodes of conducive climate, an increase in host availability due to forest management, and a particularly virulent strain(s) of the fungus. In order to avoid future epidemics, and to develop comprehensive strategies for management of lodgepole pine, such as genetic resistance, it is critical that the biology of the fungus, and the factors (such as dothistromin production) leading to outbreaks, are understood. Therefore the objectives of this project are to: 1) determine the degree of genetic variation present in the fungus in the region currently under attack; 2) determine if the strain(s) of the fungus in this region are the same as those in other regions of B.C. and the Pacific Northwest; and 3) determine if there is a relationship between genotype and production of dothistromin. Approach: Stage one of this project will develop methods for fungal sampling, observation and isolation, and molecular techniques for analysis of genetic diversity, and carry out the genetic analyses, and stage two will examine the relationship between genotype and dothistromin production.
Related projects:  FSP_Y051203FSP_Y062203


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Updated August 16, 2010 

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