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Title: SUBGROUP 16SRIII-F PHYTOPLASMA STRAINS IN AN INVASIVE PLANT, HERACLEUM SOSNOWSKYI, AND AN ORNAMENTAL, DICTAMNUS ALBUS

Author
item VALIUNAS, D - VILNIUS LITHUANIA
item SAMUITIENE, M - VILNIUS LITHUANIA
item RASOMAVICIUS, V - VILNIUS LITHUANIA
item STANIULIS, J - VILNIUS LITHUANIA
item Davis, Robert

Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2006
Publication Date: 3/1/2007
Citation: Valiunas, D., Samuitiene, M., Rasomavicius, V., Staniulis, J., Davis, R.E. 2007. Subgroup 16sriii-f phytoplasma strains in an invasive plant, Heracleum sosnowskyi, and an ornamental, Dictamnus albus. Journal of Plant Pathology. 88:137-140.

Interpretive Summary: Phytoplasmas are very small bacteria that are responsible for hundreds of diseases affecting agriculturally important plants around the world. Phytoplasmas are unlike most bacteria, in that they have no cell wall, and they cannot be isolated in laboratory culture. There is need to improve methods and tools for detecting and identifying phytoplasmas in order to aid efforts to curb the spread of diseases caused by phytoplasmas. In a study of the genome (all of the genes) in a phytoplasma, we have discovered new diseases caused by phytoplasmas in an invasive plant species, Heracleum sosnowskyi (hogweed), and an ornamental plant, Dictamnus albus (gas plant), and have cloned and determined the nucleotide sequence of a major part of the linked genes that encode RNA molecules involved in the synthesis of proteins by the phytoplasmas in the diseased plants. Based on our study of the genes, we identified the phytoplasmas as new members of the milkweed phytoplasma subgroup originally found in North America. The results of our study provide new information about the evolution of genes that are important for protein synthesis, reveal a natural enemy of a noxious, invasive weed, and indicate that hogweed may serve as a source of phytoplasma for infection of native plants such as wild blueberry and of cultivated plants, including D. albus and cultivated blueberries. This work will interest scientists and students studying the evolution of bacteria, plant diseases, and diagnostics companies, and quarantine agencies involved in pathogen detection and the control of invasive plant species.

Technical Abstract: Phytoplasma strains were detected in an aggressive and widespread, invasive plant species, Heracleum sosnowskyi (hogweed), and in an ornamental, Dictamnus albus (gas plant), exhibiting yellows disease symptoms in northern Lithuania. Analysis of PCR-amplified 16S rDNAs revealed that the strains, designated as heracleum yellows (HerY) and dictamnus stunt (DitS), respectively, belong to phytoplasma group 16SrIII (X-disease phytoplasma group) subgroup III-F (milkweed yellows phytoplasma subgroup). While subgroup III-F phytoplasma strains have been found in four plant species (Vaccinium corymbosum, V. myrtillis, H. sosnowskyi and D. albus) in Europe, Asclepias syriaca (milkweed) in North America is the only known host elsewhere, suggesting that this subgroup may be native on the European continent. We postulate that, although phytoplasma is a natural enemy of invasive hogweed in the Baltic Region, hogweed may serve as a source of subgroup III-F strains for infection of native plants such as wild blueberry and of cultivated plants, including D. albus and cultivated blueberries.