Author
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Robertson, Nancy |
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Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/6/2005 Publication Date: 11/24/2005 Citation: Robertson, N.L. 2005. A newly described plant disease complex involving two distinct viruses in a native Alaskan lily, Streptopus amplexifolius. Canadian Journal of Botany. 83(10):1257-1267. Interpretive Summary: Surveys in south central Alaska were conducted to detect and identify pathogens in native plants. Obvious diseased appearing twisted stalk plants, Streptopus amplexifolius, were found on sites that included agricultural, residential, and remote areas. Diseased plants showed symptoms of yellow-green dashes and streaks on their leaves, and varying degrees of stunting, nonviable seeds, and premature aging. The causal agent(s) were determined to be two unrelated viruses belonging to the families Potyviridae and Flexiviridae. These unique viruses occurred singly or together in a diseased plant, and often infected over fifty percent of the twisted stalk plants on a site. The viruses were mechanically transmitted to other twisted stalk plants, Chenopodium quinoa, and C. amaranticolor. Even though Streptopus sp. plants grow in arctic/temperate regions throughout the world, this survey identified the first report of a pathogen found in Streptopus, and added to the existing limited information on diseases of native plants. Technical Abstract: The etiology of a previously unknown disease in Streptopus amplexifolius, twisted stalk, was elucidated in south central Alaska. Symptomatic plants with yellow-green dashes and streaks on their leaves contained distinct viruses belonging to the family Potyviridae and/or of the family Flexiviridae genus Carlavirus. Each virus’s identity was confirmed by a combination of morphology, serology (ELISA and/or western analysis), and sequences obtained from RT-PCR products previously generated by potyvirus- or carlavirus- specific primers. The mechanical transmission of particles (purified from twisted stalk as a mixture of both viruses or as a single preparation of each virus) to S. amplexifolius, Chenopodium amaranticolor, and C. quinoa, fulfilled Koch’ postulates and confirmed a narrow host range. The relatively high incidence of infected plants and associated severe symptoms in populations from several sites in south central Alaska gave evidence that native plants are susceptible to, and are adversely affected by viral diseases. Even though Streptopus species grows throughout the temperate regions of the world, this is the first report of a pathogen infecting plants in the genus Streptopus. |
