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Molecular Plant Pathology

Differentiation of Mycosphaerella dearnessii by Cultural Characters and RAPD Analysis. Zheng -Yu Huang, Research assistant, Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706; Eugene B. Smalley(2), and Raymond P. Guries(3). (2)Professor, Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706; (3)Professor, Department of Forestry, University of Wisconsin-Madison, Madison 53706. Phytopathology 85:522-527. Accepted for publication 23 January 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-522.

Isolates of Mycosphaerella dearnessii, the causal agent of brown spot needle blight of pine, were collected from the northern and southern United States and China and analyzed for differences in cultural morphology, growth rate, conidial germination at various temperatures, and randomly applied polymorphic DNA (RAPD) markers. Differences in cultural morphology and conidial germination were detected between the northern U.S. isolates and the other sources, but not between the southern U.S. isolates and Chinese isolates. Molecular polymorphisms (RAPDs) were also detected among 43 isolates from the United States and China. Northern U.S. isolates composed a distinct "northern group," while southern U.S. and Chinese isolates composed a related "southern group." Results of this study support the existence of races within Mycosphaerella dearnessii. The southern United States appears to be the origin of the current Chinese population, as suggested by the dendrograms generated using the molecular data.

Additional keywords: brown spot disease of pine, Lecanosticta acicola, Pinus elliottii, P. palustris, P. sylvestris, P. taeda.